Matter

MatterChapter 3

2

What is Matter?• Anything that has mass and takes

up space.

2

Basic Building Blocks of Matter• Elements: Pure substances that

cannot be separated into simpler substances– Where can we find information about

elements?– Dmitri Mendeleev created the first

periodic table.

Classifications of Matter• Substances: matter that has uniform

and unchanging composition.

– Ex. Table salt, water, hydrogen, oxygen

Classifications of Matter• Mixture: combination of two or more

substances in which the substances retain their individual chemical properties– Heterogeneous: does NOT blend, can

distinguish parts– Homogeneous: does blend, CANNOT

distinguish parts• Called solutions

Compounds• Combination of two or more

elements.– Ex. Table salt (Sodium Chloride),

Water

Physical Properties of Matter

• A characteristic that can be observed without changing the composition– Ex. Density, color, odor, taste,

hardness, melting point, and boiling point, state of matter

Chemical Properties of Matter

• The ability of a substance to combine with or change into one or more other substances.– Ex. Flammability, change into a new

substance, rust

Physical vs Chemical Change

• Physical change: altering a substance appearance, but not its composition

• Chemical change: altering a substance’s composition– Be careful…this also changes its

appearance!!!

Indicators of Chemical Change

• Change of color (can also be physical change indicator)

• Change heat (exothermic/endothermic)

• Produces light• Produces gas (bubbles)• Forms precipitate (solid)• Change in smell

Liquids• Takes the shape of its container• Volume is constant• viscosity – how easily it’s poured• Fluidity – ability to flow• Compression – compressed very little, gases

have a greater ability to be compressed• Surface tension – overfilled glass of water• capillary action – meniscus, paper towels

Solids• Definite shape• Definite volume• Tightly packed particles• Crystalline – salt• Molecular – sugar – weak forces• Amorphous – glass, rubber

Gases• Do not have a definite shape• Do not have a definite volume• Can diffuse and effuse• Can be compressed and expanded• Have fluidity

States of MatterState of Matter

Definite Shape

Definite Volume

Particle Spacing

Particle Speed

Solid

Liquid

Gas

States of MatterState of Matter

Definite Shape

Definite Volume

Particle Spacing

Particle Speed

Solid YES YES VERY CLOSE

VERY SLOW

Liquid NO YES CLOSE SLOW

Gas NO NO FAR APART

FAST

Phase Changes

Gases

Solids Liquids

Condensation

Vaporization

Melting

Freezing

Sublim

ation

Depos

ition

Melting• Endothermic –heat is absorbed• Solid to a liquid • Melting point – temperature at which

the forces holding the molecules together are broken

• Example – Ice to water

Vaporization• Endothermic• Liquid to a gas• Evaporation is vaporization on the

surface• Boiling point – temperature at which

the vapor pressure of a liquid equals the external pressure

• Example: Water to steam

Sublimation• Endothermic• Solid goes directly to a gas, not

entering the liquid state• Example: Dry Ice

Condensation• Exothermic – releases heat• Opposite of vaporization – gas to

liquid• Dew in the morning• “sweat” on a glass

Deposition• Exothermic• Gas to a solid without going through

the liquid phase• Example: Snow

Freezing• Exothermic• Liquid to a solid• Freezing point – temperature when a

liquid is turned into a crystalline solid• Example: water to ice

Which is which?• Endo-all the “ hot” changes • Exo – all the “cold” changes

Phase Diagrams– Phase diagram – graph of pressure versus

temperature that shows the condition required for a specific substance to undergo a phase change

– Triple point – represents the temperature and pressure at which three phases of a substance can coexist

– Critical point- max pressure and temperature the substance can exist as a liquid

Phase Diagrams Con’t– Line that goes between liquid and solid

– whichever phase the line is leaning towards, that phase is less dense than the other

– Lines between all phases on a phase diagram indicate that both states of matter exist simultaneously (in equilibrium)

Phase Diagrams - Water

Solids

Liquids

Gas

Triple point

Temperature (°C)

Pre

ssur

e (a

tm)

217.75

373.99

1.00

100.00

Critical Point

Boiling point

Which is more dense? Solid water or liquid water?

Worksheet• Answer the questions about the

phase diagram.

Conservation of Mass• According to the Law of

Conservation of Mass states that matter can neither be created nor destroyed in a chemical change (reaction)

• Mass reactants = Mass products

Example Problem 3-1• In an experiment, 10.00 g of red

mercury (II) oxide powder is placed in an open flask and heated until it is converted to liquid mercury and oxygen gas. The liquid mercury has a mass of 9.26 g. What is the mass of oxygen formed in the reaction?

Analyze the Problem• What is/are the reactant(s)?

– Mercury (II) oxide

• What is/are the product(s)?– Oxygen and mercury

Solve for Unknown• Mass reactants = Mass products• Mass Mercury (II) oxide= Mass oxygen + Mass of Mercury

• 10.00g = x + 9.26g

• Mass of oxygen (x) = 10.00g -9.26g• Mass of oxygen = 0.74g

Percent by Mass• Is used to determine if compounds

made of the same elements are the same…

• Mass of element x 100 • Mass of compound

Example Problem• A 78.0g sample of an unknown

compound contains 12.4g of hydrogen. What is the percent by mass of hydrogen in the compound?–

% =mass of hydrogen x 100– mass of compound

– Answer: 15.9%