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Chapter 2

Section 1 - What is Matter?

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Chemistry - Study of matter and its changes

mass + takes up space = matter

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AtomsElements

Bar of gold = all same element atom is smallest unit of the bar

C

Fe Cu

O

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Compounds - 2 or more different elements chemically combined

H2O, steel, nylon

Compounds properties are different than base units!

HO

N = nylon!

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Molecule - Smallest unit of a substance

Sometimes made of same element

H2, O2, Cl2

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Chemical Formula

Symbols + Numbers (subscripts)

C16H10N2O2

H2O

C6H12O6

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Pure Substance - Made of single element or single compound

Mixtures - Combinations of substances not chemically combined

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Two Types of Mixtures:

Heterogeneous - Not uniform or evenly distributed

Homogeneous - Evenly distributed, same throughout

Flour in water

Sugar in water

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1 Which word best describes the picture below?

A Atom

B Molecule

C Compound

D Element

E Pure Substance

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2 Which word best describes the picture below?

A Atom

B Molecule

C Compound

D Element

E Pure Substance

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3 Which word best describes the picture below?

A Atom

B Molecule

C Compound

D Element

E Pure Substance

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Section 2 - Properties of Matter

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Properties of Matter

Physical Chemical

color, shape, mass, volume, density, etc

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Melting Point Boiling Point

States of Matter (physical property)

Solid

Liquid

Gas

Plasma

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Density - mass to volume relationship

MV

D =1 g

cm3water =

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Properties of Matter

Physical Chemical

describes how a substance reacts

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Reactivity

Flammability

Chemical Properties

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Physical vs Chemical

observable

do NOT change substance

generally not observable

changes substance

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Examples

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4 Which of the following descriptions are PHYSICAL properties?

A Melting Point

B Soft

C Reactive

D Red

E Flammable

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5 What is the density of an object with a volume of 5 cm3 and a mass 15 grams?

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6 Sodium (Na) will bond with Chlorine (Cl) to form Salt (NaCl). This is an example of what property of matter?

A Flammability

B Melting Point

C Density

D Reactivity

E Plasma

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Section 3 - Changes of Matter

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Physical Change

A change that does not affect chemical properties

Breaking chalk

Haircut

Melting, Boiling

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Quartz Sand

SiO2

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Sugar + Water = ?

physical change...sugar is simply dissolved, not changed

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Mixtures can be separated!

Distillation

Centrifuge

Magnets

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Chemical Change

one or more substances are changed to new substances

brown sugar + heat = carmel

caramel + heat = carbon + water

bakeing a cake

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Chemical Change example

Carbonic acid = "fizz" in pop

When opened, carbonic acid CO2 + H2O

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Chemical or Physical Change?

odor

color

light

cannot easily be "undone"

can be reversed

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7 Which method would you use if you had to separate white blood cells from red blood cells?

A Distillation

B Electric Field

C Centrifuge

D Magnets

E Burning

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8 Liquid water boiling into steam is an example of a ________ change.

A Physical

B Permanent

C Chemical

D Impossible

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9 Mixing sugar into water is an example of a _______ change.

A Physical

B Permanent

C Chemical

D Impossible