Physical Science Chapter 9 Classification of Matter Physical

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Physical Science Chapter 9 Classification of Matter

Physical Properties of Matter

-property – characteristic of a substance that describes an object

-physical property – characteristic of matter that can be observed without changing it

-color, shape, density, hardness, boiling/freezing pt, odor, etc.

-does not involve a change to something new

-chemical property- characteristic that determines how substance reacts to form other

substances

-involves a change to something new

-corrosion – destruction of metal because it combines chemically with other substances

Changes in Matter

-all changes involve an energy change

- Law of Conservation of Matter- matter cannot be gained or lost during a chemical change

-physical changes- a change in the size, shape, color, or state of matter (solid, liquid, ice)

-it only changes it’s appearance, not the actual substance

-chemical changes – change in a substance that produces a NEW substance with different

Properties (ALL CHEMICAL CHANGES ALSO PRODUCE PHYSICAL CHANGES)

-electrolysis: a chemical change produced by an electrical current

-electricity can separate the hydrogen and oxygen in water

-‘lysis’ means to break down

-clues that a chemical change has occurred :

-heat or light given off

-bubbles produced

-sound given off

-odor is produced

Composition of Matter

Matter- anything that has mass & takes up space

Pure substance: Matter in which all the particles are alike

-only 2 substances in science are:

1. Elements

2. Compounds

Element = matter that has only 1 type of atom (atoms make up elements)

Atoms= Building blocks of all matter – smallest part of element

-chemical symbols – representation for elements

- 1 or 2 letters; 1 st

capitalized, 2 nd

isn’t = Ca

-some symbols are for the Latin name - Au = Aurum (gold)

- elements are found on the Periodic Table

Compound – matter made of 2 or more elements chemically joined together, ALWAYS IN THE SAME

RATIO

-water is ALWAYS H

2

O, not H

2

O

2

or H

2

- molecules = made up of 2 or more atoms chemically combined

- smallest part of a compound

O

3

- water always has 2 Hydrogen and 1 oxygen

Mixtures – 2 or more elements or compounds that are blended, not chemically combined

-each part keeps its own properties

-can be combined in ANY ratio – 1 cup sand and 1 gallon salt or vice versa – doesn’t matter

-2 types

-Heterogeneous mixture: substances are not spread evenly throughout mixture

- pizza, chocolate that settles in bottom of cup, city air (smog particles),paint- oil

floats on top and has to be mixed in,

-Homogeneous mixture: substance are spread evenly throughout the mixture

-milk, pure water, flat pop, any element or compound

Differences between Compounds & Mixtures

Compounds

1.

2.

3.

Elements combined in certain ratio (H

Elements chemically combined

2

O)

Mixtures__________________________

Parts can be combined in any ratio

Parts physically combined

Compound has different properties from its elements Parts keep their own properties

Solutions, Suspension & Colloids

Solution: Homogeneous mixtures made of more than 1 substance –don’t settle or scatter light

2 parts:

1. solvent = substance DOING the dissolving

2. solute = substance BEING dissolved

-soluble: means it CAN be dissolved like salt in water

-insoluble: means it CAN’T be dissolve like oil in water or metal in water

Alloy = a solution made of metals that improves its properties, or produces a desired property

-

Many uses in automotive, aerospace, construction, medical, manufacturing areas

-

-

-

-

Bronze was the first alloy discovered – made of copper and tin

Brass – alloy made of copper & zinc

Steel – alloy made of iron and carbon (pure carbon = diamond)

Types of alloys

-Aluminum alloys – strong and lightweight

-Copper alloys – excellent thermal and electrical performance

-Nickel alloys- good corrosion and thermal resistance

-Titanium alloys= very strong, tough and corrosion resistant

-stainless steel alloys-very corrosion resistant

Suspensions

-

-

-

HETEROgeneous mixture in which particles are large enough to be seen

Gravity makes ‘suspended’ particles settle

Can separate parts using filter paper

Colloids

-

-

Mixtures with particles larger than solution, but smaller than suspension

Does NOT settle

-

Scatters light – cloudy looking

-Tyndall effect – ability of a colloid to scatter light

-beam of light in smoke, dust

-beams of light coming off street lights in winter on icy nights

-Brownian motion- Random motion of particles in a colloid

-dust particles swirling around (seen in sunlight beams)

-coagulation – the clumping together of particles

-destroys colloids – particles stick together and unable to stay suspended

-emulsifier- substance that allows colloids to stay mixed – egg keeps oil/water mixed in mayo

Types of Colloids

1. Foam – whipped cream, soap suds, marshmallow

2. Aerosol = fog, clouds

3. Emulsion = milk, mayo, cheese

4. Smoke = particles in air

5. Sol = jelly, pearls

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