No Whines on Chemistry Information Booklet

8/11/2019 No Whines on Chemistry Information Booklet

1/19

No Whines On ChemistrySecondary 2

Independent Studies Team

Elements, Compounds and Mixtures

Information Booklet

Solutions and Suspensions

Separation Techniques


2/19

Elements, Compounds and Mixtures 2

Elements

2

Periodic Table of Elements

2

Metals vs Non-Metals 3

Common Elements

3

Electronic Configuration + Valence Electrons (Further Learning) 9

Particles of Matter 10

Compounds

11

Mixtures

12Separation Techniques 16

Chemical Changes

16

Physical Changes 16

Physical Separation Techniques 16

1INFORMATION BOOKLET - NO WHINES ON CHEMISTRY TEAM

Table of Contents


3/19

Elements, Compounds and Mixtures

Elements

An element is a substance which cannot be broken down in to two or more

substances by chemical methods. It is:

Simplest kind of matter

Classified into the periodic table of elements.

Periodic Table of Elements

Elements are classified systemically into the periodic table of elements based

on properties. Each element has:

a symbol of 1 to 3 letters

an atomic number and nucleon number

Horizontal Row: Period

Vertical Row: Group

As one moves across a period from left to right, the properties of the elements

will change gradually from metallic to non-metallic.

Elements in the same group have similar chemical properties and will undergo

the same types of chemical reactions.



4/19

Metals vs Non-Metals

Common Elements



5/19

Copper (Atomic Number: 29, Atomic Mass: 64, Symbol: Cu, Period 4) Appearance

Shiny Reddish Brown Solid

Properties

High Melting and Boiling Point

Good Conductor of Electricity Ductile (Easily Drawn into Wires)

Malleable

Uses

Commonly used to make electrical wires

Used to make water pipes

Copper + Tin => Bronze (Alloy, Mixture)

Copper + Zinc => Brass (Alloy, Mixture)

Aluminium (Atomic Number: 13, Atomic Mass: 27, Symbol: Al, Period 3,

Group 3) Appearance

Shiny Solid

Properties

Strong and light


Good Electricity Conductor

Malleable (Can be shaped)

Uses

Make aeroplane parts (Strong and Low Density)

Make drink cans, cooking utensils and ladders

Overhead Electricity Cables

Chlorine (Atomic Number: 17, Atomic Mass: 35.5, Symbol: Cl, Period 3,

Group 7) Appearance

Greenish-Yellow Gas

Properties

Low Melting and Boiling Point

Poor Electrical Conductor

Uses

Used in bleaches for clothes



6/19

Iodine (Atomic Number: 53, Atomic Mass: 127, Symbol: I, Period 5, Group

7) Appearance

Black Crystal

Properties

Low Melting and Boiling Point Poor Electrical Conductor

Brittle

Sublimes when heated to form a violet vapour

Uses

Used as an antiseptic in medicines (Dissolves in Ethanol)

Oxygen (Atomic Number: 8, Atomic Mass: 16, Symbol: O, Period 2, Group

6)

Appearance Colourless Gas

Properties

Low Melting and Boiling Point

Poor Electrical Conductor

Uses

Used for respiration in living things

Magnesium (Atomic Number: 12, Atomic Mass: 24, Symbol: Mg, Period 3,

Group 2) Appearance

Grey Solid

Properties


Good Conductor of Electricity

Malleable

Burns with a dazzling white light

Uses

Used to make milk of magnesia (Relieve acid of indigestion) Used in distress flares (Burns with a white dazzling light)

Used in making fireworks



7/19

Iron (Atomic Number: 26, Atomic Mass: 56, Symbol: Fe, Period 4) Appearance

Grey Solid

Properties


Good Conductor of Electricity Ductile

Malleable

Uses

Make Cutlery

Carbon (Atomic Number: 6, Atomic Mass: 12, Symbol: C, Period 2, Group

4) Appearance

Exists in different forms (Allotropes): Diamond, Graphite, Soot, Charcoal) Graphite is a black solid

Diamond is the hardest known substance.

Properties

Diamond can be polished to form a shiny, reflective and transparent solid.

Graphite is very lightweight

Uses

Graphite can be used for pencil leads

Charcoal is used for fuel

Diamond is used for making drills to cut through hard metals.

Nitrogen (Atomic Number: 7, Atomic Mass: 14, Symbol: N, Period 2, Group

5) Appearance

Colourless Gas

Properties

Unreactive Element at Room Temperature

Does not burn or support combustion

Low Boiling Point

Uses

Packing of Food

Fertilisers

Freezing Agent for Food



8/19

Sulfur (Atomic Number: 16, Atomic Mass: 32, Symbol: S, Period 3, Group 6) Appearance

Yellow Powdery Solid

Properties

Poisonous

Soluble in Organic Solvent like alcohol but not water Uses

Drugs

Sulfuric Acid

Harden Rubber in the process of making tyres (Vulcanization)

Zinc (Atomic Number: 30, Atomic Mass: 65, Symbol: Zn, Period 4) Appearance

Grey Solid

Properties Good Conductor of Electricity

Strong and Corrosion Resistant

Uses

Coat Iron Sheets (Galvanised Iron)

Produce Electricity in Batteries

Galvanize Metal Gates

Zinc + Copper => Brass

Sodium (Atomic Number: 11, Atomic Mass: 23, Symbol: Na, Period 3) Appearance

Silvery Solid

Properties

Malleable and Ductile

Good Conductor of Heat and Electricity

Soft

Reacts Violently with Water

Burns with a Brilliant Golden-Yellowish Flame

Uses

Table Salt

Street Lamps

Manufacturing Glass, Pottery and Soap



9/19

Fluorine (Atomic Number: 9, Atomic Mass: 19, Symbol: F, Period 2) Appearance

Pale Yellow/White/Colourless Gas

Properties

High Poisonous

Heat Resistant Pungent Odour

Highly Reactive with all the elements except for Noble Gases

Uses

Toothpaste

Refrigeration

Uranium Hexafluoride for Nuclear Power Industry

Phosphorus (Atomic Number: 15, Atomic Mass: 31, Symbol: P, Period 3) Appearance

White / Red / Black Solid

Properties

Waxy

White Phosphorus glows in the dark and is poisonous

Black Phosphorus is made under high pressure and conducts

Red Phosphorus cannot dissolve in many liquids

Uses

Insoluble and Inert coating to many metals

Fire starters and stoppers

Fertiliser

Glows in the dark

Boron (Atomic Number: 5, Atomic Mass: 11, Symbol: B, Period 2) Appearance

Brown Powder (Amorphous Boron)

Hard, brittle, lustrous black semimetal. (Crystalline Boron)

Properties

Poor electrical conductor at room temperature, but good electrical conductor at

high temperatures. Crystalline form less reactive than amorphous form.

Oxidised slowly in air at room temperature and ignites spontaneously at high

temperatures. (Amorphous)

Uses

Glass and ceramics

Fertiliser



10/19

Electronic Configuration + Valence Electrons (Further Learning)

Atoms are made up of subatomic particles, mainly protons, neutrons and

electrons.

An electronic configuration is written as follows:

X.X.X

For example,

Boron -> 5 electrons -> 2 electron shells -> electronic configuration = 2.3

Calcium -> 20 electrons -> 4 electron shells -> electronic configuration = 2.8.8.2

Note:

Number of periods = Number of occupied electron shells

Number between each period = Number of electrons on that particular shell

Chlorine -> 17 electrons -> 3 electron shells -> 2.8.7

Chlorine has 3 electron shells -> 3 periods

Chlorine has 2 electrons on 1st shell, 8 electrons on 2nd shell, 7 electrons on

3rd shell.

Valence ShellThe valence shell is the furthest occupied shell from the nucleus. Valence

electrons refer to the electrons in the valence shell.

(only valence electrons are involved in chemicalreactions)

Examples of Borons electronic structure:

Summary of Shells1. Number of period = Number of occupied electronic shells

2. Number between each period = Number of electrons on that particular shell.

Chlorine => 17 electrons > 3 electron shells > 2.87

Chlorine has 3 electron shells > 3 periods

Chlorine has 2 electrons on 1stshell, 8 electrons on 2ndshell, 7 electrons on 3rd

shell



11/19

Particles of Matter

A Scanning Tunneling Microscope is used to see particles of matter.

There are different types of particles:

Atoms

Molecules

Ions and Isotopes (Sec 2)

Atoms Smallest Particle of Any Element

Diameter of about 0.1 * 10-9metre

Can have the chemical properties of the elements

Each element consists of particular types of atoms.

Atoms of different elements are different.

Molecules Group of 2 or more atoms held together by chemical bonds

May consist of atoms of a single element (O2), or of different elements (H2O)



12/19

Compounds

A compound is a substance containing 2 or more elements chemically

combined together.

Properties of Compounds Compounds are formed by chemical reactions. Their formation usually involves an

exchange of energy in the form of heat, light or both with the surroundings.

Properties of the compound formed have different properties from the constituent

elements.

Compounds cannot be broken down by physical methods.

Compounds can only be broken down by chemical methods which involve heating or

lighting or electric current.

Different elements in a compound are joined together in a fixed proportion by mass (and

number of atoms)

How are compounds formed? Combination An example is combustion

occurs when elements or compounds burn and combine with oxygen to form one

or more new compounds

Example of Combustion: Carbon(Element) + Oxygen(Element) => Carbon Dioxide

(Compound) / Sodium(Element) + Water (Compound) => Sodium Hydroxide

(Compound) + Hydrogen (Element)

Decomposition

Complex compounds heated to be broken down into simpler compounds. Sugar

(Compound) => Water Vapour (Compound) + Carbon (Element)

If something has no chemical formula, it is a mixture.



13/19

Mixtures

A mixture consists of two or more different substances that are mixed but not

chemically joined together.

Do not have chemically symbol or formula

Can be solids (salt and sand, metal alloys, etc.)

liquids (mineral water, milk, etc.)

gases (air)

Examples: air, mineral water, bronze, steel, brass

Two types of mixtures:

Solutions

Suspensions

Solutions Consists of 2 parts:

Solvent (the substance the solute dissolves in and forms the solution)

Solute (the substance that dissolves in the solvent of the solution)

Example:

air > nitrogen (solvent) + oxygen, carbon dioxide and etc (solute)

saltwater > water (solvent) + salt (solute)

bronze > tin (solvent) + copper (solute)

Homogenous colour, density, appearance and other physical and chemical properties

are the same in every part of the solution

Light passes through the solution (solute particles are spread evenly and thus too small to

reflect or block any light passing through)

Three types of solution:

Dilute solution small amount of solute in large amount of solvent

Concentrated solution large amount of solute dissolved in solvent

Saturated solution maximum amount of solute dissolved in solvent



14/19

SolubilityThe solubility of a substance is the maximum quantity of that substance which can dissolve

in 100 grams of the solvent a given temperature.

Eg: Copper (II) Sulfate has a solubility of 32 grams per 100 grams of water at 20 degrees

celsius.

Factors affecting solubility Type of solute

The type of solute affects solubility as different substances have different solubilities in the

same solvent.

Type of solvent

The type of solvent also affects solubility as the same substance have different solubilities in

different solvents.

TemperatureThe solubility of solids and liquids increases with the increase in temperature whereas the

solubility of gases decreases as the temperature increases.

Pressure

The solubility of gases increases with the increase in pressure whereas the solubility of solids

and liquids decreases as pressure increases. However, the effect of pressure on solubility of

solids and liquids is typically weak.

Solubility Graph

The left is a solubility graph,

which shows how the solubility

of different substances in a

solvent varies with various

factors. In this case, the

solubility graph shows the

changes in solubility ofcompounds in water with

temperature.

[Image from: http://www.sciencegeek.net/Chemistry/taters/graphics/solubility.gif]



15/19

Rate of dissolving

Rate of dissolving is the time taken for the dissolving process from the time the

solute was added to the solvent until it is completely dissolved.

Factors affecting rate of dissolving

Temperature of solvent

The temperature of the solvent affects the rate of dissolving by speeding up the process. The

particles of the solvent and solute are able to move faster in a higher temperature which

results in them mixing together more quickly. Hence, the process of dissolving in faster.

Size of solute particles

The smaller the size of the solute particles, the larger the exposed surface area of the solute

particles. Dissolving always occurs on the surface of the solute. Hence, solute particles can

dissolve faster with more exposed surface area if they are smaller. This increases the rate of

dissolving.

Agitation of the solution

By stirring or shaking the solution, it remove the solvent that has already dissolved pieces of

the solute and replaces it with fresh solvent.

*Note: Rate of dissolving is not the same as solubility.

Rate of dissolving is how fast the solute dissolves in the solvent entirely whereas solubility is

the maximum amount of solute which can dissolve in 100 grams of solvent at a particular

temperature.

SuspensionsSuspensions are formed when the substance does not dissolve in the solvent or when the

amount of substance in the mixture is over its solubility limit.

Examples:

sand in water

muddy water concrete

Properties:

Heterogeneous insoluble particles settle at the bottom so physical and chemical

properties are unequal throughout suspension.

Light does not pass through the suspension. (insoluble particles are big enough to

block incoming light)

Particles settle to the bottom after suspension is left to stand for a while.



16/19

Solutions vs Suspensions

Compounds vs Mixtures

A single compound has a fixed boiling point. A mixture of compounds have a range of boiling

points.



17/19

Separation Techniques

Chemical Changes

Chemical Change:

New substance formed Different properties (Different melting points / chemical reactions)

New substance have different appearances

A lot of heat given out in chemical change.

Chemical Reactions:

Combustion

Decomposition

Physical Changes

Physical Change:

No new substances formed.

Changes easily reversed through physical separation techniques

Example: Dissolving of salt in water

Physical Separation Techniques

Filtration

Filtration is one of the techniques used to separate mixtures. A mixture of solid and liquid is

poured into a filter funnel and passed through a filter paper. The filter paper is usually folded

into a cone shape to fit into the filter funnel. When the mixture passes through the filter paper,

the extremely tiny holes in it allow the liquid to flow through and traps the solid particles. The

solid trapped in the filter paper is known as the residue whereas the liquid that passes

through the filter paper is known as the filtrate. However, this method will only be viable if the

solid is insoluble in the liquid.

Crystallisation

When a solid dissolves in liquid, it forms a solution and thus filtration is unable to separate.

Hence, other methods like crystallisation are used. When the solution is heated, most of the

solvent is evaporated off until the solution becomes saturated. The solution is then left to

cool, causing its solubility to decrease, resulting in the dissolved solid to appear as pure

crystals. The cooled solution is then poured away to obtain the crystals, which are dried by

pressing them between sheets of filter paper.



18/19

Evaporation to dryness

Evaporation to dryness is an alternative to crystallisation. This method is slightly different from

crystallisation. The solution is heated until all the solvent is evaporated to leave behind only

the solute instead of heating the solution until it is saturated before cooling it to obtain the

crystallised solute. However, there are downfalls to evaporation to dryness as compared to

crystallisation. Evaporation to dryness cannot be used for sugar solution as sugar will

decompose to give water and carbon when heated.

Distillation vs Fractional distillation

Distillation is used to purify liquids. In The liquid is boiled and turns into gas, which is pure as

the other substances are left in the solution. The gas is then cooled and condenses to a pure

liquid which is called a distillate. This method is used to obtain a pure solvent from a solution.

An example is the distillation of seawater to obtain pure water. The seawater is boiled in a

flask and the steam is then cooled in a condenser and condenses. The pure water droplets

are then collected in a conical flask whereas the salt and other impurities remain in the flask.

However, if there is a solution of miscible liquids, then fractional distillation is used. The

difference between the two methods is the fractionating column, which separates the liquids

according to their boiling point. The lowest boiling point liquid is distilled first, allowing the

miscible liquids to be separated. However, the liquids in the solution must have different

boiling points for fractional distillation to work. For example, in a mixture of ethanol and water,

as ethanol has a lower boiling point at 78 degrees celsius, it boils and then condenses first,

leaving the water in the flask as it has a higher boiling point at 100 degrees celsius.

Separating FunnelFor non-miscible liquids, a separating funnel is used. The lighter liquid forms a separate layer

above the heavier liquid. The tap is opened so the lower liquid layer runs out first and is

collected in a beaker. The tap is quickly closed as the last drops of the liquid flows into the

beaker. Then, the tap is opened for the higher liquid layer to run out into another beaker. An

example is a mixture of water and petrol, where the water is let out and collected in beaker

before the petrol as the former is heavier than the latter.

Magnetic attraction

Magnetic attraction is used to separate magnetic substances from non-magnetic ones in amixture. Electromagnets are used to remove scrap steel and iron plus other metallic waste at

junkyards. Electromagnets are used as they are temporary magnets so they can be

activated and deactivated at the appropriate times.



19/19

Chromatography

Chromatography is used to separate a mixture into all of its various components and identify

them. There are many types of chromatography, one of them being paper chromatography. It

can be used to separate and identify dyes in black ink. Two pencil lines are drawn on a piece

of paper and a drop of black ink and other drops of coloured dye are placed on one of the

pencil lines. The paper is usually placed in a beaker of suitable solvent, in this case butanol,

ethanoic acid and water, with the pencil line just touching the solvent. The solvent travels up

the paper and splits the black ink into its different components. The paper is removed when

the paper reaches the other pencil line and then dried. Identical dyes travel the same

distance up the paper and the unknown ones can be inferred from the known ones.

Chromatography is applied in forensic science and used to ensure high food quality by

testing the purity of substances.


No Whines on Chemistry Information Booklet

Documents

Transcript of No Whines on Chemistry Information Booklet