Unit2SectionA Oct 19

8/14/2019 Unit2SectionA Oct 19

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Unit 2 Materials

Structure and UsesSection A: Why We use what we do.


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Intro to Unit 2: Materials:

Structure and Uses Topics introduced include:

Chemical and physical properties

Chemical symbols and formulas The periodic table

Reactivity of metals

Oxidation-reduction

Law of conservation of matter andenergy

Writing and balancing chemical

equations

Use of formulas to calculate molar


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Section A.1

Properties make the difference Every substance has

characteristic properties that

distinguish it form othersubstances


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Section A.1

Properties make the difference Physical properties:

Can be determined without altering the

chemical make up of the material

Color

Density

Odor

Physical changes:

Identity still stays the same

Melting

Boiling

Bending


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Section A.1:

Properties make the difference Chemical properties:

Key to the usefulness of material

(How it will react with other substances) Chemical Change

Transform into new substances

Can be detected in:

The formation of a gas or solid

A color change

Change on the surface of a solid

Temperature change


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A.2 Physical and Chemical

Properties

1. Pure metals have a higher luster (are shiny reflect light)2.The surfaces of some metals become dull when exposed

to air.3. Nitrogen gas, which is a relatively nonreactive element at

room temperature, can form nitrogen oxides at the hightemperature of an operating automobile engines

4. Milk turns sour if left too long at room temperature5. Diamonds are hard enough to be used in drill bits.6. Metals are typically ductile (can be drawn into wire).

7. Bread dough increases in volume if it is allowed to risebefore baking.

8. Argon gas, rather than air is used in many Light bulbs toprevent oxidation of metal filament.

9. Generally, metals are better conductors of heat and

electricity than are non metals.


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1. Pure metals have a higher luster (are shiny reflect light)

Physical

2. The surfaces of some metals become dull when exposed to air.Chemical the metal reacts with oxygen

3. Nitrogen gas, which is a relatively non-reactive element at roomtemperature, can form nitrogen oxides at the high temperature of anoperating automobile engines

Chemical new substances are formed

4. Milk turns sour if left too long at room temperature

Chemical material changes, depends on bacteria in milk5. Diamonds are hard enough to be used in drill bits.

Physical

6. Metals are typically ductile (can be drawn into wire).

Physical

7. Bread dough increases in volume if it is allowed to rise before baking.

Chemical bread rising is due to the production of carbon dioxide8. Argon gas, rather than air is used in many Light bulbs to prevent

oxidation of metal filament.

Chemical Argon does not react with the filament

9. Generally, metals are better conductors of heat and electricity than arenonmetals.

Physical


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Section A.4

The Chemical Elements Elements can be grouped or

classified according to theirsimilarities and differences

Metals, Nonmetals, Metalloids Metals

Iron, tin, zinc, copper

Non-Metals Carbon, Oxygen

Metalloids Silicon, germanium

Relatively few: properties are

intermediate some characteristics ofmetals, some properties of nonmetals,


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Metals, Nonmetals, &

Metalloids1

2

3

4

5

6

7

Metals

Metalloids

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 349

Nonmetals


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Metalsmost elements are

metals

elements to the left ofthe stair step line are

metals or metal likeelements


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Ph ysic a l Pr o p e r t ie so f Me ta ls:

-Luster (shininess)

-Good conductors of heat and

electricity-High density (heavy for their size)

-High melting point

-Ductile (most metals can be drawn out

into thin wires)-Malleable (most metals can behammered into thin sheets)


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Ch e mic a lP roper t i es o fMe ta ls:

-Easily lose electrons

-Corrode easily---Corrosion is agradual wearing away. (Example:

silver tarnishing and iron rusting)


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N o n m e t a l s

-found at the right of the

stair step line

-characteristics are

opposite those of metals


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Ph ysic a l Pr o p e r t ie so f No n me t a ls:

-No luster (dull appearance)

-Poor conductor of heat and electricity-Brittle (breaks easily)

-Not ductile

-Not malleable-Low density

-Low melting point


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Ch e mic a lP roper t i es o fNonmeta l s :

-Tend to gain electrons


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Meta l l o ids

-Elements on both sides of the

zigzag line have properties ofboth metals and nonmetals.


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Ph ysic a l Pr o p e r t ie so f Me ta l lo ids:

-Solids

-Can be shiny or dull

-Ductile

-Malleable

-Conduct heat and electricity

better than nonmetals but not as

well as metals

Semiconductors


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Section A.4:

The Periodic Table 60 elements found by 1800s

Five non metals

2 liquids

The rest all solids

The periodic table

An effort to impose someorganization of the information

related to the elements

Dimitri Mendeleev Russian Chemist produced periodic table


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A little bit of chemistry -

history A little about Dimitri Mendeleev

Family history

Contribution to chemistry

Julius Lothar Meyer

The original periodic table

Henry Mosley

British physicists

Contribution to chemistry


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Section A.4:

The Periodic Table Early Periodic table wasgrouped according to two

main characteristics

Atomic mass

It was known that atoms of

different elements have different

masses.

Combining capacity

How a respective element

combined with other elements.

KCl one to one ratio MgCl one to two ratio


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Section A.10:

The Periodic Table Vertical columns: groups or

families

Similar chemical properties

Horizontal rows: periods

Increasing atomic weights


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A.10 Organization of the

Periodic Table Group 1: Alkali metals (except hydrogen)

Highly reactive

Low densities

Soft enough to be cut with a knife

Group 2 Alkaline: earth metals

Groups 3-12d: transition metals Groups f: transition metals (inner transition

metals)

Group 17-Hologens Group 18: Noble gases Almost entirely un-reactive

Completely filled S and P orbital

Few noble gas compounds can be made

Hydrogen is its own family Other rou s named for first


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Homework

Page 130 #1-5, 7-12, 13-15.

Unit2SectionA Oct 19

Documents

Transcript of Unit2SectionA Oct 19