CHAPTER 2 Metals & Non-Metals - examsbazar.com · Metals & Non-Metals Chemistry, Class : VIII 27...

CHAPTER

Metals & Non-Metals 2 SUB- TOPICS Introduction

Physical properties of Metals and Non-Metals

Metalloids

Chemical properties of Metals and Non-

Metals

Metallic Reactivity Series

Displacement reaction of Metals

Uses of Metals and Non-Metals

Ores and Minerals

Occurrence of Metals.

Metallurgy.

INTRODUCTION

Through there are millions of substances in this world, they are all made up of a

limited number of basic substances, which are called elements.

Metals & Non-Metals Chemistry, Class : VIII

IIT Foundation Programme 26

You have already studied about elements as being pure substances that each are made

up of one kind of atoms only.

For convenience of study, these elements are divided into two broad classes : Metals

and non-metals.

This division of elements is based on the fact that there are certain properties that are

found only in metals and certain others that are found only in non-metals.

But, there are also some elements that show the properties of both metals and non-

metals. They are known as metalloids.

Some common metalloids are arsenic, antimony and silicon. The noble (inert) gases

from the fourth category of elements.

The majority of the elements known to us are metals.

For example gold, silver, platinum, copper, iron aluminium, tin, nickel chromium,

mercury, calcium, magnesium, lithium, sodium, potassium, zinc, and many more.

PHYSICAL PROPERTIES OR CHARACTERISTICS OF

METALS AND NON-METALS

METALS

They are generally solids with characteristics such as hardness, malleability ductility

high tensile strength, luster and ability to conduct heat and electricity. Example;

Copper, iron, zinc etc.

A solid is considered to be a metal if it has high electrical and thermal conductivity.

The chemical definition of a metal also includes having a characteristic surface luster

or shine.

It is characteristic of metals that they are malleable (can be hammered into sheets) and

ductile (can be drawn into wires.)

Usually have 1-3 electrons in their outer shell. Both the high electrical conductivity

and thermal conductivity come from the fact that one or more valence electrons is

relatively free to travel throughout the solid materials.

All metals, other than sodium (Na) and potassium (K), have high melting and boiling

points.

The melting points of sodium (Na) and potassium (K) are below 100C. The melting

point of iron is about 1540C. Metals make a characteristic sound when hit with an

object. Thus metals are sonorous.

NON-METALS

They are generally non-lustrous, brittle, poor conductors of heat and electricity. Example:

Sulphur, phosphorus, nitrogen etc.



Properties of Non-metals

Non-metals are not malleable or brittle: Non-metals cannot be hammered or beaten

into thin sheets without breaking. Non-metals break into pieces when hammered or

stretched. Sulphur, phosphorous are powders and cannot be made into a sheet. Brittleness

is a characteristic property of non-metals.

Non-metals are not ductile: Non-metals cannot be melted and drawn into thin wires.

Non-metals do not have free electrons. Thus the bonds between atoms in the elements are

weak and they snap when stretched.

Non-metals are bad conductors of heat and electricity: In non-metals, the bonds

formed are weak as there are no free electrons to share. Graphite is able to conduct

electricity because of its special crystalline arrangement.

Non-metals have no lustre: Non-metals are in the form of powder or are gaseous. Hence

they cannot be polished and they do not have any lustre. Most of the powders are dull in

colour. Only graphite can be polished to some degree. Iodine shows some luster.

Non-metals are not strong: Due to their non-ductile and non-malleable properties, non-

metals are not strong at all. Their bonds break easily.

Melting and boiling points: All non-metals have low melting and boiling points. The

melting point of sulphur (S) is 115C. Graphite and diamonds have high melting points.

Density of non-metals: Non-metals have low densities as compared to metals, which

have high densities.

Non-Metals are not Sonorous

Non-metals do not make any characteristic sound when hit with an object.

Illustrations –1: Explain the meanings of malleable and ductile.

Solution: i) Metals are malleable, that is, can be hammered (or beaten) in the very

thin sheets with a hammer, without breaking.

ii) Metals are ductile, i.e., can be drawn (or stretched) to form thin wire.

DIFFERENCES IN PHYSICAL PROPERTIES OF METALS AND NON-METALS

Metals Non Metals

1. State: Metals are crystalline solids (except

mercury, which is a liquid)

2. Metallic lustre: In their pure state, metals

shine. This property is called metallic lustre.

In other words, metals can be polished.

3. Density : Metals has high density (except

sodium, potassium and lithium)

4. Hardness : Metals are hard solids (except

sodium and potassium, which are soft and can

be cut with a knife).

Non-metals are either gases or solids

[Exception: Bromine is a liquid]

Non-metals are dull to look at, i.e., they

cannot be polished [Exceptions: Graphite

and iodine are lustrous].

Non-metals have low density [Exception :

Diamond has high density].

Non-metals are not hard. If solid they are

soft and brittle. For example, phosphorus

and sulphur are soft solids and iodine is



5. Melting point: Metals have high melting

points and high boiling points

6. Malleability : Metals are malleable, i.e., they

can be hammered into sheets. Gold, silver,

copper, aluminium and tin can be beaten into

very thin sheets called foils. (But zinc is

brittle, i.e., it breaks into pieces when it is

hammered).

7. Ductility : Metals are ductile, i.e., they can be

drawn into wires. Gold, silver, copper and

aluminium are highly ductile metals, gold

being the most ductile of all metals.

[Exception : Zinc, arsenic & antimony cannot

be drawn into wires].

8. Tensile strength: Metals have high tensile

strength, i.e., they can bear a lot of strain

[Exception : Zinc].

9. Thermal and electrical conductivity: Metals

are good conductors of heat and electricity.

Silver is the best conductor of heat and

electricity.

10. Sonority: Metals produce a twangy sound

when they are struck with a hard object, i.e.,

they are sonorous substances.

brittle [Exception : Diamond is the hardest

natural substance].

Non-metals have both low melting and

low boiling points [Exceptions : Carbon,

silicon and boron have both high melting

and high boiling points].

Non-metals are non-malleable. When they

are hammered they turn into a powder,

i.e., non-metals are of a brittle nature.

Non-metals are not ductile [Exception:

Carbon fibre, a recently developed

allotrope of carbon, is ductile]

Non-metals have low tensile strength

[Exception: Carbon fibre has high tensile

strength].

Non-metals are band conductors of heat

and electricity [Exceptions: Graphite and

good conductor of heat and electricity].

Solid non-metals do not produce a sound

when they are struck, i.e., they are not

sonorous substances.

METALLOIDS

These elements have characteristics common to metals and non-metals. Example:

Arsenic, tin, bismuth etc.

The semimetals or metalloids include silicon and germanium and other elements which

possess properties intermediate between those of metals and non-metals. Silicon, for

example, possesses a metallic luster, yet it is inefficient conductor and is brittle. The

intermediate conductivity of metalloids means they tend to make good semiconductors.



Illustrations –2: What are metalloids?

Solution: Those elements which have characteristic properties of both metals and non-

metals are known as metalloids Examples germanium, Silicon, tellurium and

antimony.

CHEMICAL PROPERTIES OR CHARACTERISTICS OF METALS AND

NON-METALS

METALS 1. Reaction of metals with oxygen

i) In the presence of heat, most metals react with oxygen (or air) to form their

respective oxides. These metallic oxides are of a basic nature. Therefore they are

known as basic oxides. Basic oxides form salt and water when they react with

acids.

Metal + Oxygen heat Oxide (basic)

2 Cu + O2 2 CuO (baisc oxide)

ii) On the other hand, metals like sodium and potassium react vigorously with

oxygen (even in the absence of heat) to form their respective oxides.

E.g.:

2 2sodium oxygen Sodium oxide

4Na O 2Na O

2 2Potassium Potassiumoxygen

oxide

4K O 2K O

2CalciumCalcium Oxygenoxide

2Ca O 2CaO

iii) Metals like magnesium, aluminium, zinc, iron, lead, copper and mercury react

with oxygen on heating to from oxides that are basic in nature but insoluble in

water, i.e., they are not alkaline [but magnesium hydroxide is alkaline in nature].

E.g.:

heat

2Magnsiummagnesium Oxygenoxide

2Mg O 2MgO

heat

2zinc Zincoxideoxygen

2Zn O 2ZnO

heat

2CopperCopper Oxygenoxide

2Cu O 2CuO

Metals like silver, gold and platinum do not react with oxygen even on strong

heating. Therefore they are called noble metals.

2. Reaction of metals with water

Depending upon their level of reactivity, metals react with water or steam to form

their corresponding metallic hydroxides or oxides, along with hydrogen gas.

i) Metals like sodium and potassium react violently with cold water to form their

hydroxides as well as hydrogen gas.



The reaction is so vigorous that a fire or an explosion can occur. Calcium too

reacts with cold water to from its hydroxide and hydrogen, but the reaction is a

moderate one.

Metal + cold

Watermetallic hydroxide + Hydrogen

E.g.:

vigorous

2 2sodium sodium hydroxidecold water hydrogen

analkali

2Na 2H O 2NaOH H

very

2 2vigorouspotassium Potassium hydroxidecold water hydrogen

2K 2H O 2KOH H

moderate

2 22calcium cold water hydrogencalciumhydroxide

Ca 2H O Ca OH H

ii) Metals like magnesium, aluminium, zinc and iron react with steam to from their

respective oxides as well as hydrogen gas.

Metal + Steam heat Metal Oxide + Hydrogen

E.g.:

heat

2 2magnesiummagnesium steam hydrogenoxide

Mg H O MgO H

heat

2 3 4 2red hot triferricsteam hydrogeniron tetroxide

3Fe 4H O Fe O 4H

Metals like gold, silver, copper and mercury react with neither cold water nor

steam.

3. Reaction of metals with mineral acids.

Metals react with dilute hydrochloric acid or dilute sulphuric acid to produce their

corresponding salts as well as hydrogen.

Nitric acid is not used because, being a strong oxidizing agent, it immediately

oxidizes hydrogen to produce water.

Sodium and potassium react vigorously with dilute acids, with the liberation of a

tremendous amount of heat; magnesium, calcium, zinc and aluminium react only

moderately with acids, whereas iron reacts with acids very slowly.

Metal + Acid (dil) Salt + Hydrogen

vigorous

2dil. hydrochloric sodiumsodium

hydrgoenacid chloride

2Na 2HC 2NaC H g

not so vigorous

2 4 4 2zinc zincdil sulphuric acid hydrogen

sulphate

Zn H SO ZnSO H g

slow

2 2dilhydrochloriciron ferrous hydrogenacid chloride

Fe 2HC FeC H g

Note: Lead, copper, silver and gold do not all react with dilute

mineral acids.

Metals like Cu, Zn react with concentrated acids.



For example, when Cu react with conc. H2SO4, salt, water an sulphur dioxide

gas are produced.

2 4 4 2 2conc.

Cu 2H SO CuSO SO 2H O .

NON-METALS

1. Reaction of non-metals with oxygen

Non-metals react with oxygen (air) on heating to form their respective oxides.

Most of these oxides are acidic in nature and they turn moist red litmus paper

blue.

Non-metal + Oxygen heat Non-metallic oxide

i) Carbon burns in oxygen to produce carbon dioxide.

heat

2 2carbon oxygen carbon dioxide

C O CO

ii) Sulphur burns in oxygen to produce sulphur dioxide

heat

2 2sulphur oxygen sulphur dioxide

S O SO

Some non-metallic oxides are natural e.g., water (H2O), carbon monoxide (CO),

nitric oxide (NO) and nitrous oxide (N2O).

iii) Hydrogen burns in oxygen to produce water, which is a neutral oxide i.e., it

does not change the colour of indicators.

2 2 2hydrogen oxygen water

2H O 2H O .

2. Reaction of acidic oxides and acids with bases / alkalis

i) Carbon dioxide and sulphur dioxide react with sodium hydroxide to produce the

salts sodium carbonate and sodium sulphite respectively, along with water.

Acidic oxide + Base Salt + Water

2 2 3 2

sodiumcarbon sodium waterhydroxidedioxide carbonate

CO 2NaOH Na CO H O

2 2 3 2

sodiumsulphur sodium waterhydroxidedioxide sulphite

SO 2NaOH Na SO H O .

3. Reaction with water

i) Carbon dioxide dissolves in water and forms carbonic acid.

2 2 2 3

carbon carbonicwaterdioxide acid

CO H O H CO

ii) Sulphur dioxide gives sulphurous acid with water.

2 2 2 3

sulphur sulphurouswaterdioxide acid

SO H O H SO



4. Reaction of non-metals with acids

Non-metals do not react with dil. HC or H2SO4. But they react with concentrated

acids.

Some of the reactions are as follows:

2 4 2 2 2conc

C 2H SO CO 2SO 2H O

2 4 2 2S 2H SO 3SO 2H O

3 3 4 2 2conc.

P 5HNO H PO 5NO H O

3 2 4 2 2conc.

S 6HNO H SO 6NO 2H O .

Illustrations –3: Write equation for the reactions of:

i) iron with steam

ii) Calcium and potassium with water

Solution: i) 3Fe(s) + 4H2O(g) Fe3O4(s) + 4H2(g)

ii) Ca(s) + 2H2O(l) Ca(OH)2(aq) + H2(g)

2K(s) + 2H2O (l) 2KOH(aq) + H2(g) + Heat energy.

METAL REACTIVITY SERIES

The reactivity of metals depends on the ease with which they loose electrons. The metals

are placed in increasing order of reactivity into a serfies called Metal Activity Series.

Metals Activity Series

K Na Ca Mg Al Sn Fe Sn Pb [H] Cu Hg Ag Au

Significance of Metal Activity Series

Metal activity series is a series in which

a) the metals are arranged in decreasing order of reactivity.

b) {H} is the demarcating element.

c) metals above {H} can displace H from an acid.

d) metals below {H} cannot displace H from an acid.

e) a more reative metal can displace a less reactive metal from a salt.

Reason for reactivity is that metals higher up in the series loose electrons more easily.

Metals below [H] are found free in nature. Those above [H] are not found free in nature.

Special features of the activity series:

1. The ease with which a metal in solution loses electron(s) and forms a positive ion

decreases down the series i.e., from potassium to gold.

2. Hydrogen is included in the activity series because, like metals do, it too loses an

electron and becomes positively charged (H+) in most chemical reactions.

3. If facilitates the comparative study of metals in terms of the degree of their

reactivity.



The reactivity series of metals

Elements Reaction with oxygen Reaction with water Reaction with acid

1. K

2. Na

3. Ca

React with oxygen at

ordinary temperature to

form oxides (1, 2 & 3)

React with cold water

vigorously (1 &2); reacts

moderately with water (3)

React explosively with

dilute acids to give

hydrogen (1 & 2);

reacts less vigorously

(3)

4. Mg

5. Al

6. Zn

7. Fe

Form oxides on heating,

but aluminium reacts at

ordinary temperature (4,

6 & 7)

Reacts with hot water or

steam (4); react with steam

only to form oxide &

hydrogen (5, 6 & 7)

React moderately with

acid, to produce

hydrogen (4, 5, 6 & 7)

8. Pb

9. [H]

10. Cu

11. Hg

Form oxides on very

strong heating (8, 10 &

11)

No reaction with hot water

or steam (8, 10 & 11)

Reacts with conc. HCl

to give H2(8); do nto

react with dilute acids

(10 & 11)

12. Ag

13. Pt

14. Au

Do not react with

oxygen even on strong

heating (12, 13 & 14)

No reaction with hot water

or steam (12, 13 & 14)

Do not react with dilute

acids (12, 13 & 14)

Illustrations –4: Samples of four metals A, B, C and D were taken and added to the

following solution one by one. The result obtained have been tabulated as

follows:

Metal Iron(II) sulphate Copper (II)

sulphate

Zinc

sulphate

Silver

nitrate

A No reaction Displacement — —

B Displacement — No reaction —

C No reaction No reaction No reaction Displacement

D No reaction No reaction No reaction No reaction

Answer the following questions about metals A, B, C and D:

i) Which is the most reactive?

ii) What would you observe when B is added to a solution of copper (II)

sulphate?

iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.

Solution: i) B is the most reactive.

ii) When B is added to a solution of copper (II) sulphate, then B displaces

copper from copper sulphate solution.

B get coated with red brown layer of copper and the colour of copper

sulphate solution fades.

iii) B A C D.

DISPLACEMENT REACTION OF METALS

It has been found that a more reactive metal always displaces a less reactive metal from

the slat solution. This can be better understood by the following activities.

Some more displacement reactions are as follows:

Zn + CuSO4 ZnZO4 + Cu



[Zn is more reactive than Cu]

Mg + FeSO4 MgSO4 + Fe

[Mg is more reactive than Fe].

Illustrations –5: What would you observe when zinc is added to a solution of iron (II)

sulphate? Write the chemical reaction that takes place.

Solution: Zinc displaces iron from iron (II) sulphate solution to form zinc sulphate and

ion metal.

4 4Greenish solution Colourless solution

FeSO (aq) Zn(s) ZnSO (aq) Fe(s)

USES OF METALS AND NON-METALS

USES OF SOME COMMON METALS COPPER

Copper was among the first metals discovered by man along with gold and silver. It is

reddish brown in colour.

It is highly ductile , i.e., capable of being drawn into wires, and also a very good

conductor of heat and electricity.

It is used in making:

i) electric wires and cables, utensils and semi-precious ornaments.

ii) coins and statues (in the form of its two alloys, brass and bronze).

iii) electronic devices.

iv) several electroplating operations.

The use of copper in the electrical goods industry has declined due to the increasing

use of aluminium as its substitute. Also copper is costly.

IRON

There are three different varieties of manufactured iron, depending mainly on the

proportion of carbon present in it.

These are:

a) pig iron (or cast iron)

b) wrought iron

c) steel

Wrought iron is the purest form of iron, since it has the least proportion of carbon

present in it, while pig iron is the most impure form of iron, since it has the highest

proportion of carbon present in it.

Steel is the most widely used form of impure iron, to the extent of being the very basis

of modern life.

Iron is used in the manufacture of:

i) radiators, railings, manhole lids, drain pipes [in the form of pig iron].

ii) tanks, cylinders, smaller pipes, agricultural tools, nails and bolts, furniture, gates, etc.

[in the form of wrought iron].

iii) bridges, ships, machine parts, automobiles, buildings and utensils [in the form of

steel].

iv) power transmission towers.



ALUMINIUM

Aluminium is definitely the second most useful metal today, after iron.

It is silvery white in colour, malleable, ductile, light and strong, and it is a vbery good

conductor of heat and electricity as well.

Also it is resistant to corrosion. Therefore aluminium finds widerange applications.

It is used

i) to make utensils, cans for drinks, furniture, window frames, etc.

ii) in making electric wires.

iii) for packaging of foodstuffs (in the form of aluminium foil).

iv) as a paint ingredient (in the form of its powder mixed with linseed oil, which

protects against rusting when applied to the surface of iron).

v) to make the bodies of aircraft and automobiles, and a machine parts and tools.

This is because, in the form of its alloys duralumin and magnalium, it is light and

very strong.

vi) in making mirrors (as reflector material).

ZINC Zinc is used

i) to make dry cells and electrodes.

ii) to make alloys like brass and bronze that are used to make utensils, statues,

decoration pieces, etc.

iii) to coat (galvanization) iron sheets so as to prevent them from rusting.

iv) in the extraction of silver and gold from their ores.

LEAD It is used for:

i) making pipes and other sanitary fittings, bullet tips and tin roofs.

ii) covering underground electric and telephone cables.

iii) making solder and type metal.

iv) the preparation of compounds like lead sulphate, red lead and litharge, which are

used in paint and emulsion products.

v) making screens that protect against X-rays and other radioactive radiations.

MAGNESIUM It is used:

i) in preparing fireworks, since it burns with a dazzling light.

ii) in the preparation of alloys like duralumin and magnalium.

iii) for making fuse wire.

iv) in nuclear reactors for the absorption of neutrons.

TIN It is used:

i) to make cans for storage of foodstuffs.

ii) for coating of utensils made of other metals so as to prevent them from corroding.

CALCIUM In its various combined states, calcium has wide applications

i) Calcium chloride is used as a drying agent, i.e., for physical removal of water.



ii) Calcium carbonate is used in the manufacture of glass, cement, lime, washing soda

etc.

iii) Marble, a non-crystalline form of calcium carbonate, is used for building and

laboratory purposes. It is used also to make statues.

iv) Chalk, another form of calcium carbonate, is used for distempering of walls, in

toothpastes and talcum powder, and in medicines for indigestion etc.

GOLD: Therefore it is used in

i) the manufacture of electronic devices like telephones, computers, etc.

ii) making ornaments and coins.

iii) dentistry to fill into teeth cavities (in the form of amalgam, an alloy made of gold,

silver and mercury).

SILVER It is used

i) for making jewellery, since it is fairly scarce and therefore semi-precious.

ii) for filling into teeth cavities (in the form of amalgam, an alloy made of gold,

silver and mercury).

iii) as a water purifier

iv) for making electrodes and in several electroplating operations.

v) in photography (in the form of silver nitrate and silver bromide).

vi) in the form of silver iodide to seed clouds in order to crate “artificial rain”.

Though silver is the best known metallic conductor of electricity and the most

ductile metal, it is not used for making electric wires. This is because it is rather

costly and not a chemically stable as is required for transmission of electricity.

MERCURY

Mercury is a silvery white, liquid metal. It does not moisten glass and it expands a lost

on heating.

Therefore it is used in

i) thermonmeters (as themometric liquid):

ii) barometers and other scientific apparatus.

iii) dentistry, for filling into teeth cavities in the form of alloys known as silver

amalgam and gold amalgam.

PLATINUM It is used

i) for making electrodes and electrolytic cells.

ii) for making expensive ornaments and watches.

uses of some common non –metals

Non-metals too play a vital role in everyday life.

Proteins, carbohydrates and fats are made mostly of the non-metals carbon, hydrogen,

oxygen and nitrogen.

We need oxygen to breathe and plants need carbon dioxide for photosynthesis.



Non-metals are also important for the manufacture of a number of industrial

substances.

The uses of some commonly known non-metals are discussed below:—

OXYGEN Oxygen is used

i) For respiration and combustion.

ii) For artificial respiration for patients suffering from breathing problems (in the

form of carbogen, a mixture of 95% oxygen and 5% carbon dioxide).

iii) For artificial respiration by people in special occupations. Deep sea divers,

mountaineers, astronauts, miners and firemen carry oxygen cylinders with

them.

iv) To weld and cut metals.

v) In the extraction of iron and manufacture of steel. Oxygen reacts with the

impurities of the crude iron ores to form ferrous oxides.

vi) In the manufacture of sulphuric and nitric acids.

vii) For blasting of rocks in the mining industry; carbon dust (carbon mixed with

liquid oxygen) is used as an explosive, a substitute for dynamite.

viii) As a propellant for spacecraft; liquid oxygen (LOX) helps to burn hydrogen.

Oxygen is carried in containers attached to the spaceships since, in space,

there is no oxygen.

NITROGEN

It is slightly lighter than air. It is neither combustible nor supporter of combustion.

Nitrogen is an important component of human food nutrients.

i) Nitrogen plays an important role in controlling the rate of combustion. It dilutes

the oxygen present in the air that we breathe, otherwise, pure oxygen would burn

our lungs.

ii) It is an important constituent of proteins, which are necessary for the growth of

animals, plants and human beings. Plants convert nitrogen into proteins.

iii) It is used in the manufacture of compounds like ammonia and nitric acid.

iv) It is used to make fertilizers like ammonium salts, urea, potassium nitrate, etc.

v) It is used to prepare explosives like T.N.T. (Trinitro toluene)

vi) Because of its inert nature, nitrogen is used for preservation of food. The

containers used for storing foodstuffs are flushed with nitrogen (to remove

oxygen) before they are packed and sealed. The absence of oxygen does not allow

for bacterial growth. Thus food remains fresh for a long time.

During a thunderstorm, when lightning occurs, nitrogen and oxygen in the

atmosphere combine to form oxides of nitrogen, which are washed away with rain

(in the form of nitric acid) into the soil.



CHLORINE Chlorine is used

i) As a bleaching agent for rough and hand fibres like jute and cotton.

ii) As a disinfectant for sterilizing both drinking water and swimming pool water.

iii) In the manufacture of mineral acids like hydrogen chloride.

iv) In the manufacture of chemicals like D.D.T. (Dichloro diphenyl trichloro ethane),

B.H.C (Benzene hexachloride) and bleaching powder (CaOCl2), which are used as

an insecticide, a pesticide and a disinfectant, respectively.

SULPHUR

Sulphur is yellow solid. It is brittle in nature. In free state in occurs in volcanic

regions, while in combined stte it occurs as sulphates, sulphides, etc.

Substances like garlic, onion, eggs, hair and wool contain sulphur. Sulphur in

small amounts is a vital ingredient for the human body.

Sulphur has wide applications

i) It is used in the chemical industry for the manufacture of sulphuric acid, sodium

thiosulphate (used in photography), gunpowder, dyes, matches and fireworks.

ii) It is used in the medical industry:

to prepare skin ointments, since it has excellent fungicidal properties.

to fumigate disease-infected areas (in the form of sulphur vapour)

to purify blood (in the form of a colloidal solution).

to prepare homeopathic and ayurvedic medicines.

to prepare a range of other medicinal drugs.

iii) Sulphur powder is used as an insecticide and as a fungicide.

PHOSPHOROUS

In combined state phosphorus occurs as phosphates. It is present in the brain, the

bones and the teeth of animals [in the form of calcium phosphate [Ca3(PO4)2] and

in plant cells.

i) White phosphorus is used as rate poison. It is used also in fireworks because of its

inflammable nature.

ii) Phosphorus is used in the manufacture of fertilizers, detergents and fine

chinaware.

iii) Phosphorus sulphide is used on the sides of safety match boxes.

SILICON

Silicon is one of the most useful elements available to modern man. It does not

occur free in nature.

In combined state however it ranks next only to oxygen in abundance i.e., as sand.

[The chemical name of sand is silica (SiO2)].

i) Highly purified silicon is used in making microchips for computers,

transistors, solar cells, rectifiers and other solid state devices that are used

extensively in the electronic and the space age industries.



ii) Silicon is used in the manufacture of “silicone”, a waterproof material.

iii) It is used also to prepare silicon carbide, which is the hardest substance prepared

by man. It is used as the grinding agent in various kinds of grinding tools.

iv) In the form of sand to prepare concrete, bricks and cement. Sand is the principal

ingredient of glass.

v) In the form of silicates, silicon is used in enamel, pottery, etc., and for preserving

eggs.

vi) Silicon is an important ingredient in steel, an alloy of iron.

IODINE It is used

i) In the form of iodized slat for the healthy growth of the human body. Iodine

deficiency causes goiter and other thyroid based diseases.

ii) In Photographic films (in the form of potassium iodide).

iii) to make tincture of iodine and iodex, which are used as disinfectant and pain

reliever respectively.

FLUORINE

i) Fluorine is used mainly in the production of fluorides and fluorocarbon

compounds.

ii) In the form of stannous fluoride it is used in toothpastes to prevent dental decay,

especially in children.

iii) Fluorine is used to prepare a type of plastic known as teflon. Teflon is thermally

stable and chemically resistant. Therefore, it is widely used as an insulator and as

a lubricant.

Illustrations –6: A man went door to door posing as a goldsmith. He promised to bring back

the gilitter of old and dull gold ornaments. An unsuspecting lady gave a set of

gold bangles to him which he dipped in a particular solution. The bangles

sparkled like new but their weight was reduced drastically. The lady upset but

after a futile argument the man beat a hasty retreat. Can you play the detective

to find out the nature of the solution he had used?

Solution: The solution he has used may be aquaregia which is 3 parts of conc. HCl and

1 part of HNO3. It can dissolve noble metals such as gold.

Aqua-regia dissolved a considerable amount of gold bangles and hence

reduce their weight drastically. The man can recover the dissolved gold from

aqua-regia by a suitable treatment.

ORES AND MINERALS

MINERALS The naturally occurring compounds of metals mixed with earthly impurities like sand,

clay, stone, etc., are called minerals. They are found beneath the earth’s surface as the

chemical ingredients of rocks.



GANGUE Earthly impurities like sand, clay and mud, when they are present in an ore, are called

gangue or matrix.

ORES An ore is a mixture of minerals from which elements or compounds are extracted.

Generally ores are not exploited unless it can be done profitably.

Mineral + Gangue = Ore

COMMON ORES AND THE METALS EXTRACTED FROM THEM

Type of ore Ore Chemical formula Metal extracted

Oxide ores

Bauxite

Haematite

Magnetite

Zincite

Cuprite

A 2O3.2H2O

Fe2O3

Fe3O4

ZnO

Cu2O

A

Fe

Fe

Zn

Cu

Sulphide ores

Galena

Copper glance

Iron pyrite

Zinc blende

Cinnabar

PbS

CuS

FeS2

ZnS

HgS

Pb

Cu

Fe

Zn

Hg

Carbonate ores

Marble

Magnesite

Siderite

Malachite

Chalk

CaCO3

MgCO3

FeCO3

[CuCO3.Cu(OH)2]

CaCO3

Ca

Mg

Fe

Cu

Ca

Sulphate ores Epsom slat

Gypsum

MgSO4.7H2O

CaSO4.2H2O

Mg

Ca

Halide ores

Rock salt

Horn silver

Fluorspar

Cryolite

NaC

AgC

CaF2

A F3.3NaF

Na

Ag

Ca

A

Illustrations –7: a) Why is sulphide ore converted to its oxide before reduction?

b) What is thermite reaction?

Solution: a) Sulphide ore is converted to first oxide before reduction because

oxygen can easily be removed from metal oxides by reacting it with

carbon or aluminium or by electrolytic reduction.

b) Reduction of certain metal oxide (MnO2, Fe2O3, Cr2O3) to metal by

using aluminium as a reducing agent is known as thermite reaction.

For example,

3MnO2(s) + 4Al(s) 3Mn(l) + 2Al2O3(s)

Fe2O3(s) + 2Al(s) 2Fe(l) + Al2O3(s)



OCCURRENCE OF METALS

The knowledge of metals is very old. Copper was perhaps the first metal to be

used by man for making utensils, weapons and other objects.

Most metals have a significant role in our daily life. They constitute the mineral

wealth of a country.

Metals occur in nature in both free (native) and combined states.

NATIVE OR FREE STATE

Gold and platinum are found exclusively in free state because they are non-

reactive elements.

Also, due to their low reactivity, copper, mercury and silver too occur mostly in

native or free state.

COMBINED STATE

Most metals occur in nature in combination with other substances, since metals

are mostly reactive.

Mainly they occur as oxides, sulphides, sulphates, carbonates and silicates.

The relative abundance of metals in the earth’s crust.

Metal Percentage

proportion

Metal Percentage

proportion

Aluminium 8 Sodium 2.5

Iron 6 Potassium 1.5

Calcium 5 Other metals 2

Magnesium 3

Illustrations –8: Gold and silver often occur in free state, Why?

Solution: Gold and Silver are least reactive, therefore occur in free state.

METALLURGY

The scientific principles and the physical and the chemical processes that are applied

to obtain pure metals from their ores constitute the science of metallurgy.

The extraction of a metal for its ore depends on:

a) The type of ore being used,

b) the nature of the impurities present in the ore,

c) the degree of the reactivity of the metal that is to be extracted.

Usually the following consecutive steps are involved in metallurgical processes.

1. Ore dressing, i.e., concentration of ore.

2. Conversion of concentrated ore into metal oxide.

3. Reduction of metal oxide to impure metal.

4. Refining of impure metal.



1. Ore decreasing or concentration of ore:

The process of removal of gangue (earthly impurities) from an ore is known

as concentration or dressing ore.

The purified ore is called concentrate. Concentration is done to increase the

proportion of metal in ore.

It begins with the crushing of the ore in big pulverizers so as to obtain

powdered ore.

Some common methods of concentration are:

i) Hydraulic washing (gravity separation)

ii) Froath flotation

iii) Magnetic separation.

i) Hydraulic washing

This method exploits the difference in the density of the ore and the density of

gangue. Therefore, it is also known as the gravity separation method.

The ores of tin and lead are concentrated by this method.

ii) Froth flotation

This process is based on the difference in the consequences when ore and gangue

are wetted with certain liquids.

Mainly oil and water are used for this purpose.

Froth flotation is used to concentrate the sulphide ores of copper, lead and zinc.

iii) Magnetic separation:

This method exploits the difference in the respective magnetic properties of ore

and gangue.

Impurities of iron ore are removed by this process since, as you known, iron has

magnetic properties.

Nickel and manganese too are separated using this method from their ores, since

they are ferrous metals.

2. Conversion of the concentrated ore into metallic oxide:

Concentrated ore is converted into metal oxide by either:

i) Roasting

ii) Calcination



The choice of method depends upon the physical and the chemical nature of

the ore.

i) Roasting

The process of heating concentrated ore to a high temperature in excess air is

known as roasting. Roasting is most commonly carried out on sulphide ores.

Roasting:

removes water from concentrated ore.

removes volatile impurities like arsenic and phosphorus from ores.

converts ore into oxide.

makes ores porous.

Examples:

a)

roasting

2 2copper copper sulphurairsulphide oxide dioxide

2CuS 3O 2CuO 2SO

b)

roasting

2 2leadlead sulphide sulphurairmonoxide dioxide

2PbS 3O 2PbO 2SO

c)

roasting

2 2zinc sulphide zinc oxide sulphurair

dioxide

2ZnS 3O 2ZnO 2SO

d)

roasting

2 2 3 2ferrous sulphurair ferric oxidesulphide dioxide

4FeS 7O 2Fe O 4SO

ii) Calcination

The process of strongly heating a concentrated ore in the absence of air to a

temperature that is insufficient to melt the ore is known as calcination.

removes moisture and volatile impurities like CO2 from ores.

converts carbonate ores into metallic oxides.

makes ores porous.

Examples:

a)

calcination

3 2copper oxidecopper carbon dioxide

carbonate

CuCO CuO CO

b)

calcination

3 2lead oxidelead carbon dioxide

carbonate

PbCO PbO CO

c)

calcination

3 2zincoxidezinc carbon dioxide

carbonate

ZnCO ZnO CO

3. Reduction of metal oxide to metal (smelting):

The process of the removal of oxygen from a metallic oxide so as to convert is (the

metallic oxide) into a metal is known as reduction (or smelting).

This impurity too gets removed either by using a reducing agent or by the process of

electrolysis.

i) Reduction by electrolysis:



Highly reactive metals like potassium, sodium, calcium, magnesium and

aluminium are extracted by the process of electrolysis, since they do not get

reduced by conventional reducing agents.

ii) Reduction by conventional reducing agents

In this process the metallic oxide is reduced to metal by using reducing agents like

carbon (coke or charcoal), carbon monoxide, hydrogen, etc.

Mostly, metals like zinc, lead, iron and copper are extracted from their

corresponding oxides this way.

Examples

a) zinc zinccoke carbon monoxideoxide

ZnO C Zn CO

b) lead coke lead carbon monoxidemonoxide

PbO C Pb CO

c)

heat

2 3 2carbon ironferric carbon dioxidemonoxideoxide

Fe O 3CO 2Fe 3CO

d)

heat

2copper carbon copper carbon dioxideoxide monoxide

CuO CO Cu CO

FLUX

The substance added to the ore to remove its impurities during the reduction of

oxidised ore from primary ore is called flux.

SLAG

The substance formed by the chemical combination of flux and ore based impurities

is called slag. Since, slag is a fusible compound it gets separated from the ore easily.

ii) Reduction by thermal decomposition:

Oxides of metals like mercury and silver get reduced to their corresponding meals

on heating above 300ºC.

They do not require a reducing agent or electrolytic reduction for this propose.

4. Refining of impure metals

Refining of impure metals is the process of the removal of physical and chemical

impurities still present in the metal that has been sorted out (extracted) from its

ore. Such ‘first-stage’ extracted metals mainly contain the following impurities:

i) other metals in pure or impure form.

ii) non-metals.

iii) dissolved gases.

Some common methods of refining impure metals are distillation, liquefaction,

oxidation, electro-refining, etc.

However the best method is electro-refining, since it gives highly pure (99% –

99.9%) metal.



Electro-refining of impure metal (Refining by electrolysis) is the most widely

used process for purification of impure metals.

Most commonly the pure forms of copper, zinc, tin, aluminium, nickel chromium,

silver and gold are obtained by this process.

When electric current is passed through the electrolyte, it (the electrolyte)

dissociates into free metal ions and thus pure metal gets deposited at the negative

electrode (cathode).

The mass of impurities that settles down in the solution below the anode is known

as anode mud.

Illustrations –9: What are the different steps of metallurgical processes?

Solution: (i) Dressing and concentration of ore.

(ii) Conversion of ore to oxide or desired compound.

(iii) Extraction of Metal.

(iv) Retiring of Metal.



KKEEYY PPOOIINNTTSS

AAtt pprreesseenntt,, mmoorree tthhaann 111188 cchheemmiiccaall eelleemmeennttss aarree kknnoowwnn.. EEaacchh eelleemmeenntt hhaass aa sseett ooff

cchhaarraacctteerriissttiicc pprrooppeerrttiieess..

MMeettaallss mmaayy aallssoo ooccccuurr iinn tthhee ffrreeee oorr nnaattiivvee ssttaattee ee..gg..,, ssiillvveerr,, ggoolldd..

AA mmiinneerraall ffrroomm wwhhiicchh tthhee mmeettaall ccaann bbee eexxttrraacctteedd eeaassiillyy aanndd pprrooffiittaabbllyy iiss ccaalllleedd aann oorree..

MMeettaallss hhaavvee aa lluusstteerr,, kknnoowwnn aass mmeettaalllliicc lluusstteerr.. TThheeyy ccaann bbee ppoolliisshheedd..

MMeettaallss,, iinn ggeenneerraall,, hhaavvee hhiigghh ddeennssiittiieess..

EExxcceeppttiioonnss:: NNaa KK hhaavvee llooww ddeennssiittiieess.. TThheeyy aarree lliigghhtteerr tthhaann wwaatteerr..

MMeettaallss,, uussuuaallllyy hhaavvee hhiigghh mmeellttiinngg aanndd bbooiilliinngg ppooiinnttss.. EExxcceeppttiioonnss:: NNaa aanndd KK hhaavvee llooww

mmeellttiinngg aanndd bbooiilliinngg ppooiinnttss..

MMeettaallss aarree mmaalllleeaabbllee ((ii..ee..,, tthheeyy ccaann bbee hhaammmmeerreedd iinnttoo sshheeeettss)) aanndd dduuccttiillee ((ii..ee..,, tthheeyy ccaann bbee

ddrraawwnn iinnttoo wwiirreess))..

MMeettaallss aarree ggoooodd ccoonndduuccttoorrss ooff hheeaatt..

MMeettaallss aarree ggoooodd ccoonndduuccttoorrss ooff eelleeccttrriicciittyy.. ‘‘AAgg’’ aanndd ‘‘CCuu’’ aarree tthhee bbeesstt ccoonndduuccttoorrss,, ffoolllloowweedd

bbyy AAll aanndd FFee..

IIff yyoouu hhiitt aa mmeettaall wwiitthh aa hhaarrdd oobbjjeecctt,, yyoouu ccaann hheeaarr aa cchhaarraacctteerriissttiicc ssoouunndd kknnoowwnn aass aa

mmeettaalllliicc cclliinnkk ((ssoonnoorriittyy))..

NNoonn mmeettaallss uussuuaallllyy hhaavvee nnoo lluusstteerr.. TThheeyy aarree dduullll llooookkiinngg.. UUssuuaallllyy tthheeyy ccaannnnoott bbee

ppoolliisshheedd..

EExxcceeppttiioonnss:: GGrraapphhiittee aanndd iiooddiinnee aarree LLuussttrroouuss..

NNoonn mmeettaallss eexxiisstt aass ggaasseess aanndd ssoofftt ssoolliiddss..

EExxcceeppttiioonnss:: DDiiaammoonndd iiss aa hhaarrdd ssoolliidd aanndd bbrroommiinnee iiss aa lliiqquuiidd..

NNoonn--mmeettaallss hhaavvee llooww ddeennssiittiieess..

NNoonn mmeettaallss uussuuaallllyy hhaavvee llooww mmeellttiinngg aanndd bbooiilliinngg ppooiinnttss..

EExxcceeppttiioonnss:: DDiiaammoonndd aanndd ggrraapphhiittee hhaavvee vveerryy hhiigghh mmeellttiinngg aanndd bbooiilliinngg ppooiinnttss..

SSoolliidd nnoonn--mmeettaallss aarree bbrriittttllee rraatthheerr tthhaann mmaalllleeaabbllee aanndd dduuccttiillee..

NNoonn--mmeettaallss aarree bbaadd ccoonndduuccttoorrss ooff hheeaatt..

NNoonn--mmeettaallss uussuuaallllyy ddoo nnoott ffoorrmm aallllooyyss wwiitthh eeaacchh ootthheerr..



AASSSSIIGGNNMMEENNTT –– II

1*. Why is sodium kept immersed in kerosene oil?

2*. Which one of the following metals does not react with oxygen even at high temperatures?

(i)Calcium (ii) Gold (iii) Sodium

3*. Name any one metal which reacts neither with cold water nor with hot water but reacts

with steam to produce hydrogen gas.

4*. Name two metals which are both ductile as well as malleable.

5*. Write the chemical equation for the reaction of hot aluminium with steam.

6. The property due to which a metal can be beaten into sheets is called

(A) Ductility (B) Tenacity

(C) Malleability (D) Density

7. A non-metal which is a good conductor of heat and electricity, is

(A) Phosphorus (B) Silicon

(C) Graphite (D) Sulphur

8. Which is not the property of a metal?

(A) malleability (B) ductility

(C) form acidic oxides (D) conductivity

9. What are the properties of a metal?

(A) Malleable (B) Ductile

(C) Form acidic oxides (D) Conductor

10. What are the properties of a non – metal?

(A) Forms anion (B) Have tensile strength

(C) High density (D) Forms acidic oxides

11. The property of metals by which they can be beaten into thin sheets is called-

(A) malleability (B) Ductility

(C) conduction (D) Expansion

12. Which one of the following is metal?

(A) C (B) N

(C) Na (D) O

13. Which one of the following is non metal?

(A) Zn (B) Al

(C) Fe (D) N



14. All materials shown property of malleability except

(A) Iron (B) Graphite

(C) Aluminium (D) Silver

15. Which one of the following is a good conductor of electricity?

(A) Iron (B) Plastic

(C) Wood (D) Glass

16. The property of metal by which it can be drawn into wires is called

(A) Conductivity (B) malleability

(C) Ductility (D) Decorating

17. The metals that produce ringing sounds, are said to be-

(A) malleable (B) sonorous

(C) Lustrous (D) hard

18. Which metal is found in liquid state at room temperature?

(A) Fe (B) Zn

(C) Hg (D) Al

19. Which material show shiny appearance?

(A) Coal (B) Sulphur

(C) Aluminium (D) Carbon

20. Gold is used in-

(A) Thermometers (B) Fuel

(C) Jewellery (D) Machinery.



AASSSSIIGGNNMMEENNTT –– IIII

1*. Which gas is produced when dilute hydrochloric acid is added to reactive metal? Write a

chemical reaction when iron reacts with dilute H2SO4.

2*. What type of oxides are formed when non-metals combine with oxygen?

3*. Name of the iron compound in haematite. Write its chemical formula.

4*. Name two metals which can form hydrides with hydrogen.

5*. What would you observe when zinc is added to a solution of iron(II) sulphate? Write the

chemical reaction that takes place.

6. The oxide of sodium is of

(A) Acidic nature (B) Neutral nature

(C) Amphoteric nature (D) Basic nature

7. Metals more active than hydrogen, react with dilute mineral acid and displace

(A) Hydrogen gas (B) Nitrogen gas

(C) Carbon monoxide gas (D) Oxygen gas

8. When an aluminium strip is kept immersed in freshly prepared ferrous sulphate solution

taken in a test tube, the change observed is that

(A) The green solution slowly turns brown

(B) The lower end of the test tube becomes slightly warm

(C) A colourless gas with smell of burning sulphur is observed

(D) Light green solution changes to blue

9. When zinc is added to CuSO4 solution prepared in water, the solution becomes :

(A) Green in colour (B) Blue in colour

(C) Pale yellow in colour (D) Colourless

10. When you place an iron nail in copper sulphate solution, the reddish brown coating

formed on the nail is :

(A) Soft and dull (B) Hard and flaky

(C) Smooth and shining (D) Rough and granular

11. Which of the following will not evolve CO2 upon heating?

(A) CaCO3 (B) MgCO3

(C) ZnCO3 (D) Na2CO3

12. The solution of ash of magnesium ribbon is-

(A) Acidic (B) Basic

(C) Neutral (D) All of these



13. What is the product when sulphur reacts with oxygen?

(A) Sulphuric acid (B) Sulphur trioxide

(C) Sulphurous acid (D) Sulphur dioxide

14. When sulphur dioxide is dissolve in water then-

(A) Sulphur is formed (B) Sulphur trioxide is formed

(C) Sulphuric acid is formed (D) Sulphurous acid is formed

15. What is the chemical formula of sulphurous acid-

(A) H2SO4 (B) SO2

(C) SO3 (D) H2SO3

16. The sulphuric acid turns blue litmus paper into-

(A) Red (B) Green

(C) Yellow (D) Dark blue

17. Oxides of non metals are _______ in nature

(A) Basic (B) Acidic

(C) Neutral (D) All of these

18. Sodium metal is stored in-

(A) Water (B) Alcohol

(C) Kerosene (D) Ether

19. Which one of the following metal reacts vigorously with oxygen and water?

(A) Sodium (B) Potassium

(C) Calcium (D) Magnesium

20. Which metal is present in Calcium Hydroxide?

(A) C (B) O

(C) Ca (D) H



AASSSSIIGGNNMMEENNTT –– IIIIII

1*. Give the reason why copper is used to make hot water tanks but steel (an alloy of iron) is

not.

2*. Sodium is more reactive than copper, why?

3*. How will you show that silver is less reactive than copper?

4*. What is a thermite reaction?

5*. Which important properties of aluminium are responsible for its great demand in

industry?

6. The ore of iron is

(A) Bauxite (B) Malachite

(C) Cuprite (D) Haematite

7. Iron nail were dipped in a solution kept in a test tube. After half an hour, it was observed

that the colour of the solution had changed. The solution in the test tube was that of

(A) Zinc sulphate (B) Copper sulphate

(C) Iron sulphate (D) Aluminium sulphate

8. A student puts one big iron nail in four test tubes containing solutions of zinc sulphate,

aluminium sulphate, copper sulphate and iron sulphate. A reddish brown coating was

observed only on the surface of iron nail which was put in the solution of


(C) Iron sulphate (D) Aluminium sulphate

9. 10 mL of freshly prepared iron sulphate was taken in each of four test tubes. Strips of

copper, iron, zinc and aluminium were introduced in these tubes. A black residue was

obtained in two of them. The right pair of metals forming the precipitates is :

(A) Copper and zinc (B) Aluminium and copper

(C) Iron and aluminium (D) Zinc and aluminium

10. Four test tube were taken and marked A, B, C and D respectively. 2 mL of solution of

Al2(SO4)3 in water was filled in each of the four test tubes. Clean piece of metal Zn was

placed in test tube A, clean iron nail was put in test tube B, clean copper wire was placed

in test tube C and a clean aluminium wire was placed in test tube D. It was observed that

no change occurred in any of the test tubes. The correct inference drawn is :

(A) Zinc is less active than aluminium

(B) Zinc is less active than copper

(C) Copper is less active than aluminium

(D) Aluminium is inert in its solution

11. On burning metals react with oxygen to produce-

(A) Metal hydroxide (B) Metal chloride

(C) Metal oxide (D) Metal sulphate



12. Which non metal is essential for our life and inhale during breathing?

(A) H (B) O

(C) C (D) N

13. Non metals are used in-

(A) Aeroplanes (B) making machinery

(C) Water boilers (D) Fertilisers

14. Which one of the following is applied on wounds as an antiseptic?

(A) Metals (B) Non metals

(C) Metalloids (D) All of these

15. Which metal is found in plants?

(A) Fe (B) Cr

(C) Mg (D) Co

16. Copper sulphate (CuSO4) possesses

(A) Red colour (B) Blue colour

(C) Green colour (D) Yellow colour

17. Which one of the following are very reactive non metals

(A) Sodium (B) Potassium

(C) Carbon (D) Phosphorous

18. Which material is hard in nature?

(A) Iron (B) Coal

(C) Oxygen (D) Wood

19. Which one of the following metal is used in thermometers?

(A) Copper (B) Mercury

(C) Aluminium (D) Iron

20. Zinc replaces copper from-


(C) sulphuric acid (D) Copper oxide



AASSSSIIGGNNMMEENNTT –– IIVV

1*. A solution of CuSO4 was kept in an iron pot. After a few days, the iron pot was found to

have a large number of holes in it. Write the equation for the reaction that took place.

Explain the reaction in terms of reactivity of the metals.

2*. The covalent bond in HCl shows ionic character. Give reasons.

3* a) What is the nature of the compound when

i) sodium reacts with oxygen

ii) magnesium reacts with chlorine?

b) Arrange the following:

i) NaCl, MgCl2, AlCl3 in increasing order of covalent nature.

ii) LiCl, LiBr, LiI in increasing order of ionic nature.

c) How many electrons are shared by each atom in the formation of:

i) a double bond

ii) a triple bond?

d) What is a polar covalent bond? Illustrate with one example.

e) Name the type of compounds which are soluble in:

i) non-polar covalent solvents

ii) polar solvents

4*. (i) Name an important ore of iron. Write its formula.

(ii) How is this ore concentrated?

5*. State reasons for the following:

(i) Aluminium oxide is called an amphoteric oxide.

(ii) Sodium and potassium metals are kept immersed under kerosene oil.

(iii) Hydrogen gas is not evolved when most metals react with nitric acid.

6. The ores which are generally subjected to roasting are

(A) Carbonates ores (B) Oxide ores

(C) Sulphide ores (D) Chloride ores

7. Gold Ornaments are normally made from :

(A) 24 carat gold (B) 22 carat gold

(C) 16 carat gold (D) 20 carat gold

8. Parts of aeroplanes are generally made from

(A) Phosphor bronze (B) Monel Metal

(C) Magnallium (D) Duralumin

9. The correct order of decreasing reactivity of Zn, Cu, Fe and Al is

(A) Zn > Cu > Fe > Al (B) Al > Fe > Zn > Cu

(C) Al > Zn > Fe > Cu (D) Zn > Al > Fe > Cu



10. Calcination is the process of heating the ore :

(A) in absence of air (B) in the presence of air

(C) in a blast furnace (D) none of these

11. Which gas produced by piece of burning charcoal?

(A) CO2 (B) CO

(C) H2S (D) O2

12. Which one of the following is the good conducter of electricity?

(A) Iron rod (B) Sulphur

(C) Coal piece (D) Wood

13. Which one of the following can’t be drawn into wires?

(A) Fe (B) Al

(C) Cu (D) Coal

14. Which substance is present in fuel?

(A) Copper (B) Iron

(C) Gold (D) Carbon

15. Metallic oxides are-

(A) Acidic is nature (B) Neutral

(C) Basic in nature (D) Either acidic or basic

16. Aluminium foil are used for wrapping

(A) Food (B) Clothes

(C) Plastic (D) Wires

17. Which one of the following is used for decorating sweets?

(A) Aluminium foil (B) Copper foil

(C) Silver foil (D) All of these

18. Which one of the following enhances the growth of plants?

(A) Industrial gadgets (B) Fertilisers

(C) Automobiles (D) Water boilers

19. Which one of the following is in crackers?

(A) metals (B) Semi metals

(C) Non-metal (D) All of these

20. Moist air is the combination of-

(A) H2O+CO2+O2 (B) H2O+ CO+O2

(C) H2O+CO2+H2 (D) H2O+O2+H2



AASSSSIIGGNNMMEENNTT –– VV

1*. What is mineral?

2*. What is an ore?

3*. What is gangue or matrix?

4*. Which method is used to concentrate bauxite ore?

5*. Which method is used to reduce the oxides of highly reactive metals?

6. A process employed for the concentration of sulphide ore is

(A) Froth Floatation (B) Gravity separation

(C) Calcination (D) Electrolysis

7. During smelting an additional substance is added which combines with impurities to form

a fusible product. It is known as :

(A) Slag (B) Mud

(C) Gangue (D) Flux

8. All ores are minerals while all minerals are not ores because :

(A) The metal cannot be extracted economically from all the minerals

(B) Minerals are complex compounds

(C) The minerals are obtained from mines

(D) All statements are correct

9. The common method for the extraction of metals from the oxide ore is :

(A) Reduction with hydrogen (B) Reduction with carbon

(C) Reduction with aluminium (D) Electrolytic method

10. The electroyte used in the electro-refining of copper is:

(A) copper nitrate (B) copper chloride

(C) copper sulphate (D) copper acetate.

11. What happens when dilute sulphuric acid is poured on a copper plate?

(A) Copper sulphate is formed (B) Zinc sulphate is formed

(C) Copper chloride is formed (D) Zinc sulphate is formed

12. Calcination of an ore results in

(i) Removal of moisture (ii) porosity of ore

(iii) removal of volatile impurities (iv) converts carbonate ore to oxide

(v) removes water of crystallization from hydrated ores.

(A) (i) and (iv) (B) (iii) and (iv)

(C) (iii) (D) all five options



13. Roasting of an ore results in

(A) conversion of ore to oxide (B) metals in it

(C) makes it conducting (D) makes it soluble.

14. Froth flotation is a method used for

(A) carbonate ores (B) hydrated ores

(C) sulphide ores (D) oxide ores.

15. Dressing and concentrating of an ore results in

(A) increase of metal ore concentration (B) decrease in metal ore concentration

(C) conversion of ore to suitable form (D) cleans the ore.

16. Extraction of metal is done by

(i) electrolytic process (ii) using carbon

(iii) using CO (iv) using Al powder

(A) (i) and (iv) (B) (i) and (ii)

(C) (i) & (iii) (D) all of the four options

17. Highly electropositive metals can not be reduced by using

(i) Electrolytic process (ii) using carbon

(iii) using CO (iv) using Al powder

(A) all except (i) (B) all except (ii)

(C) all except (iii) (D) all except (iv).

18. A flux has all or some of these benefits except

(A) Lowers melting point

(B) improves conductivity

(C) reacts chemically with impurities like sand.

(D) refines the metal



CCOOMMPPEETTIITTIIVVEE CCOORRNNEERR Straight Objective Type

This section contains multiple choice questions. Each question has 4 choices (A), (B), (C), (D), out of which ONLY

ONE is correct. Choose the correct option.

1. Bauxite is an ore of [NTSE - 2008]

(A) Boron (B) Aluminium

(C) Barium (D) Chromium

2. Which of the following will take place in the

given figure?

(A) Iron displaces oxygen from CuSO4

(B) Iron displaces Cu from CuSO4

(C) Iron displaces S from CuSO4

(D) No reaction takes place

Iron nails

CuSO4

[NSO – 2007]

3. Iron and steel are protected from corrosion by coating them with a layer of tin or

chromium metals. This process is called ___

(A) Galvanisation (B) Electroplating [NSO – 2007]

(C) Greasing (D) Painting

4. Choose the reactions which are not feasible

(I) Iron + Zinc sulphate Iron sulphate + Zinc [NSO – 2009]

(II) Magnesium + Silver nitrate Magnesium nitrate + Silver

(III) Copper + dil. Sulphuric acid Iron + Zinc sulphate

(A) I, II and III (B) III and IV only

(C) I and III only (D) All of these

5. Which among the following is carbonate ore? [NTSE –2010]

(A) Hametite (B) Argentite

(C) Magnesite (D) Gypsum

6. Mona observed the hydrogen gas is evolved in test tube 3 only when it was boiled. Test

tube 3 contains only _____

(A) Zn (B) Na [NSO – 2009]

(C) Mg (D) Cu

7. Which of the following metal is used for making boats because it does not corrode by

seawater? [NTSE –2009]

(A) Cu (B) Ni

(C) W (D) Ti

8. Which of the following is a neutralization reaction? [NSO – 2007]

(A) CuO + H2 Cu + H2O (B) NaOH + HCl NaCl + H2O

(C) 2NH3 + 3Cl2 N2 + 6HCl (D) 2H2S + SO2 2H2O + 3S



9. The property of metals which makes them useful as ringing bells is ____

(A) Malleability (B) Ductility [NSO – 2007]

(C) Sonority (D) Hardness

10. The percentage of iron in pig iron is about [NTSE –2010]

(A) 50% (B) 30%

(C) 93% (D) 5%

11. Pick up the correct statement [NTSE –2009]

(A) All ores are minerals (B) All minerals are ores

(C) A mineral cannot be an ore (D) An ore cannot be a mineral

12. Most of the metals, which occur in native state in nature [NTSE –2009]

(A) are very reactive (B) do not form ionic compounds

(C) are not reactive (D) have low density

13. Samples of four different oxides were taken and dissolved in water separately to form the

respective oxide solution. The four solutions were then tested for their acidic/basic nature.

When dissolved in water, which of the following oxides, is likely to turn blue litmus red?

(A) SO2 (B) MgO [NSO – 2008]

(C) Fe2O3 (D) CaO

14. Which of the following is a common product formed in the reaction of metals with acids

and in reaction of metals with bases?

(A) H2 gas (B) O2 gas [NSO – 2008]

(C) CO2 gas (D) N2 gas

15. Reactivity order of the above mentioned metal is _____

(A) Sodium > Magnesium > Zinc > Iron > Copper [NSO – 2009]

(B) Sodium > Magnesium > Iron > Copper >Zinc

(C) Sodium > Magnesium > Zinc > Copper > Iron

(D) Sodium > Magnesium > Copper > Iron > Zinc

Multiple Correct Answer Type

This section contains multiple choice questions. Each question has 4 choices (A), (B), (C), (D), out of

which ONE or MORE is correct. Choose the correct options.

16. Which of the following statement (s) are true?

(A) Among all the naturally occurring elements, around eighty percent are metals.

(B) Non – metals are more abundant than metals.

(C) Sodium and potassium are soft like wax.

(D) Bromine is a reddish brown liquid at room temperature.

17. The basic oxides reacts with acids to form:

(A) Salt (B) Water

(C) Metalloid (D) All



18. Hydrogen gas is not produce when metal react with-

(A) Acid (B) Base

(C) Salt (D) Both acid & base

19. Which of the following beaten into sheets?

(A) Zinc (B) Iron

(C) Aluminium (D) Sulphur

20. Heat conduction is not the property of

(A) Non-metal (B) Metal

(C) Metalloids (D) All of these

Linked Comprehension Type

This section contains paragraphs. Based upon each paragraph multiple choice questions have to be answered. Each

question has 4 choices (A), (B), (C) and (D), out of which ONLY ONE is correct. Choose the correct option.

In the extraction of metals, the less electro positive metals are reduced by chemical methods

while the more electro positive metals are reduced by electrolysis. In general ores are converted

to their oxides and then reduced by chemical reducing agents. The more electro positive metals

are reduced with difficulty by chemical methods. For such metals extraction by electrolytic

reduction is preferred. During electrolysis of these metals’ compounds, the molecules dissociate

into ions. The metal ions migrate to the cathode where they get reduced by accepting electrons.

However for the less electro positive metals, electrolytic reduction is relatively more expensive.

The chemical method using reducing agents like Carbon or Carbon monoxide is preferred.

21. Metals that are easily reduced from their oxides are __________ reactive.

(A) more (B) less

(C) as (D) not.

22. In electrolysis, reduction takes place at ________________ (electrode).

(A) cathode (B) anode

(C) anti-cathode (D) bottom.

23. In general the electrolyte used in the electrolytic extraction of metals is in the fused state

rather than an aqueous solution. This is because

(A) the salt is insoluble (B) to keep metal dry

(C) water is poor conductor (D) to eliminate H+ ions.

Assertion – Reason Type questions

This section contains certain number of questions. Each question contains Statement – 1 (Assertion) and

Statement – 2 (Reason). Each question has 4 choices (A), (B), (C) and (D) out of which ONLY ONE is

correct Choose the correct option.

(A) Statement–1 is True, Statement–2 is True; Statement–2 is a correct explanation for Statement–1.

(B) Statement–1 is True, Statement–2 is True; Statement–2 is not a correct explanation for Statement–

1.

(C) Statement–1 is True, Statement–2 is False.

(D) Statement–1 is False, Statement–2 is True.



24. Statement –1: Metals are sonorous.

Statement –2: Metals are generally brittle in the solid state, they break into pieces when

hammered.

25. Statement –1: Graphite is used as anode.

Statement –2: Graphite helps in electron conduction.

Matrix Match Type

This section contains Matrix-Match Type questions. Each question contains statements given in two

columns which have to be matched. Statements (A, B, C, D) in Column–I have to be matched with

statements (p, q, r, s) in Column–II. The answers to these questions have to be appropriately bubbled as

illustrated in the following example.

If the correct matches are A-p, A-s, B-q, B-r, C-p, C-q and D-s, then the correctly bubbled 4 4 matrix

should be as follows:

26. Column – I Column - II

(A) Ductile (p) The property of making resonating sound.

(B) Malleable (q) A substance can be drawn into wires.

(C) Sonority (r) Ability to withstand the longitudinal pull.

(D) Stainless steel (s) Not ability to withstand the longitudinal pull.

27. Column – I Column - II

(A) Brass (p) Aircrafts, pressure cooker

(B) Bronze (q) Utensils, automobile parts, cutlery

(C) Duralumin (r) Ornaments, bolts, utensils

(D) Stainless steel (s) Statues, coins

28. Column - I Column - II

(A) Forth floatation process (p) Zinc sulphide

(B) Magnetic separation (q) Ferric Oxide

(C) Thermit process (r) Chromium oxide

(D) Leaching (s) Aluminium oxide.

Integer Answer Type

29. How many metals are liquid at room temperature?

30. How many non-metals are hard?

31. How many metals have low melting and boiling point?

32. How many metals are not malleable?

33. How many non-metals are good conductors of electricity?



KEY & HINTS Metals & Non-Metals

AASSSSIIGGNNMMEENNTT –– II 1. Sodium is kept immersed in kerosene

oil because on exposure to moist air

the surface of sodium is tarnished due

to the formation of sodium carbonate

layer.

2 2

2 2

H O CO

2 3

4Na O 2Na O

2NaOH Na CO

2. (ii) Gold does not react with oxygen

even at high temperatures.

3. Iron: 3Fe(s) + 4H2O(g) Fe3O4(s)

+ 4H2(g).

4. Gold and Silver.

5. 2Al(s) + 3H2O(g) Al2O3(s) +

3H2(g).

6. (C)

7. (C)

8. (C)

9. (A), (B), (D)

10. (A), (C), (D)

11. (A)

12. (C)

13. (D)

14. (B)

15. (A)

16. (C)

17. (B)

18. (C)

19. (C)

20. (C)

AASSSSIIGGNNMMEENNTT –– IIII 1. Hydrogen gas is produced when dilute

hydrochloric acid is added to a

reactive metal.

Fe(s) + 2HCl (aq) FeCl2(aq)

+ H2(g)

2. Acidic oxides.

3. Fe2O3, Ferric oxide.

4. Sodium and Potassium

5. The solution becomes colourless and

iron metal gets deposited.

4 4Zn FeSO ZnSO Fe .

6. (D)

7. (A)

8. (B)

A displacement reaction takes place

2Al (s) + 3FeSO4 (aq) Al2(SO4)3

(aq) + 3Fe (s)

It is of exothermic nature. As a result,

the lower end of the tube becomes

warm.

9. (D)

The solution becomes colourless and a

brown deposit is formed at the bottom

of the container. This is on account of

the displacement of copper by zinc.

Zn (s) + CuSO4 (aq)

ZnSO4 (aq) + Cu(s)

(colourless)

10. (A)

The deposit on the iron nail is that of

copper displaced during the reaction.

It is soft and dull in appearance.

11. (D)

Sodium carbonate (Na2CO3) will not

evolve carbon dioxide (CO2) upon

heating to evolve carbon dioxide gas.

12. (B)

13. (D)

14. (D)

15. (D)

16. (A)

17. (B)

18. (C)

19. (A)

20. (C)

AASSSSIIGGNNMMEENNTT –– IIIIII 1. Copper is used to make hot water

tanks because it is an extremely good

conductor of heat.

2. Sodium can lose electrons more easily

than Cu, therefore it is more reactive

than Cu.

(i) Sodium reacts with water

explosively, whereas copper does not

react.

(ii) 2Na + CuSO4 Na2SO4 + Cu.

3. Silver cannot displace copper from

copper nitrate, therefore, Ag is less

reactive than Cu. On the other hand,

copper can displace silver from

AgNO3 solution.

4. Fe2O3 + 2Al Al2O3 + 2Fe

is thermite reaction.

5. (i) It is light.

(ii) It is malleable and ductile.

(iii) It does not get corroded.

6. (D)

7. (B)

Based on the activity series, the

correct decreasing order of reactivity

of metals is

Al > Zn > Fe > Cu

8. (B)

Displacement reaction involving iron

and copper sulphate was possible only in tube

(B)

Fe (s) + CuSO4 (aq)

FESO4 (aq) + Cu (s)

Reddish brown

Now reaction could not be possible in

tube (A), (C) and (D).

9. (D)

Zinc and aluminium will displace iron

from ferrous sulphate solution to form

a black residue of iron. Actually, both

these metals lie above iron in the

activity series of metals.

10. (D)

Zinc, iron and copper are less reactive

than aluminium. This is further

supported by the reactivity series of

metals.

11. (C)

12. (B)

13. (D)

14. (B)

15. (C)

16. (B)

17. (D)

18. (A)

19. (B)

20. (B)

AASSSSIIGGNNMMEENNTT –– IIVV 1. Iron is more reactive (or more electro-

positive) than copper. So, when a

solution of copper sulphate is kept in

an iron pot, iron gets dissolved. This

causes holes in the iron pot. The

reaction between iron and copper

sulphate solution is

4 4From the pot

Fe(s) CuSO (aq) FeSO (aq) Cu(s)

Or Fe(s) + Cu2+(aq) Fe2+(aq) +

Cu(s)

2. When a covalent bond is formed

between the atoms of different

elements, the bonding elements are not

equally shared by the two atoms. In

H—Cl; the shared pair of electrons is

attracted more towards chlorine.

Chlorine has 17 protons in its nucleus

to attract the shared pair of electrons.

The shared pair is always from

hydrogen because it has only proton in

its nucleus. Therefore, chlorine

acquires a slight negative charge ( )



and H acquires a slight positive charge

( ) . Therefore, HCl molecule is

polar and exhibits ionic character.

H Cl .

3. a) i) Nature of compound is ionic

or electrovalent.

ii) Nature of compound is ionic

or electrovalent.

b) i) NaCl MgCl2 AlCl3

ii) LiI LiBr LiCl

c) i) Two electrons pairs are

shared between the two atoms.

ii) Three electron pairs are

shared between the two atoms

d) When a covalent bond is formed

between two unlike atoms, such

that the shared pair of electrons

are not equidistant from each

other bonded atom then the

covalent bond so formed is called

polar covalent bond.

Example: The covalent bond

between hydrogen and chlorine

atoms in hydrogen chloride is a

polar covalent bond.

e) i) Covalent compounds are

soluble in non-polar solvent,

such as alcohol, ether,

benzene etc.

ii) Ionic compounds are soluble

in polar solvents, such as water.

4. (i) Haematite is an important ore of

iron. Its formula is Fe2O3.

(ii) It is concentrated by hydraulic

washing followed by calcinations

so as to remove moisture and

volatile impurities.

5. (i) It reacts with both acid as well as

base therefore, it is called amphoteric

oxide.

(ii) It is because they are highly

reactive and catch fire in moist air.

(iii) It is because nitric acid is strong

oxidizing agent.

6. (B)

7. (B)

Purification of gold is expressed in

carat. Pure gold is 24 carat. Gold

ornaments are generally make from 22

carrat gold.

8. (D)

Duralumin which is an alloy of

aluminium is used for making parts of

aeroplanes.

9. (C)

It is according to the activity series of

metals.

10. (A)

11. (B)

12. (A)

13. (D)

14. (D)

15. (C)

16. (A)

17. (C)

18. (B)

19. (C)

20. (A)

AASSSSIIGGNNMMEENNTT –– VV 1. Mineral is a naturally occurring

substance from which metal may or

may not be extracted profitably.

2. Ore is a rocky material which contains

sufficient quantity of mineral so that

extraction of meal is worthwhile.

3. Gangue or matrix is rocky material

present along with the mineral in an

ore.

4. Chemical separation (i.e. leaching) is

used to concentrate bauxite ore.

5. Electrolytic reduction is used to reduce

oxide of highly reactive metals.

6. (A)

Froth floatation is used for the

concentration of sulphide ore of

metals.

7. (D)



Flux is a substance which may be

either acidic oxide (SiO2) or basic

oxide (CaO, MgO). It combines with

certain impurities (gangue particles) in

ores to form a substance called slag.

This can be easily removed. For more

details consult text part.

8. (A)

A metal may exist in a number of

combined states known as minerals.

However, all of them may not be

processed for its extraction due to

many factors particularly its cost of

production. The mineral which is

actually used for the extraction of

metal is called ore.

9. (B)

Oxide of most of the metals are

reduced to carbon in the form of coke.

The process is known as smelting and

is carried in Blast furnace.

10. (C)

11. (A)

12. (D)

13. (A)

14. (C)

15. (A)

16. (D)

17. (A)

18. (D)

CCOOMMPPEETTIITTIIVVEE CCOORRNNEERR 1. (B)

2. (B)

3. (B)

4. (C)

5. (C)

6. (A)

7. (D)

8. (B)

9. (C)

10. (C)

11 (A)

12. (C)

13. (A)

14. (A)

15. (A)

16. (A, C, D)

17. (A)

18. (B, C, D)

19. (A, B, C)

20. (A, C)

21. (B)

Metals that are less reactive are more

easily reduced, as they are not very

electro positive.

22. (A)

The cations (Positively charged ions)

migrate to the cathode and gain

electrons. So, the cations are reduced

at the cathode.

23. (D)

Electrolytic reduction is preferred for

more electro positive metals. Besides

hydrogen is below the more

electropositive metals in the Metal

Activity Series. Hydrogen will be

preferentially discharged at cathode.

Another reason is that such electro

positive metals react easily with water.

If an aqueous solution of the metal salt

is taken as electrolyte, the metal after

reduction reacts with the water

present. Hence the electrolytes (salts

of these metals) are fused in this

method.

24. (C)

25. (A)

26. A→ q, B→ r, C→ p, D→ s

27. (A→ r); (B→ s); (C→ p); (D→ q)

28. (A→ p); (B→ q); (C→ r); (D→ s)

29. 2

Mercury and gallium are liquids at

room temperature.

30. 1

Diamond is hardest, naturally

occurring substance.



31. 4

Sodium, potassium, mercury and

gallium metals have low melting and

boiling point.

32. 3

Zinc, arsenic and antimony are not

malleable metals.

33. 2

Graphite and gas carbon are good

conductors of electricity?

CHAPTER 2 Metals & Non-Metals - examsbazar.com · Metals & Non-Metals Chemistry, Class : VIII 27...

Documents

Transcript of CHAPTER 2 Metals & Non-Metals - examsbazar.com · Metals & Non-Metals Chemistry, Class : VIII 27...