MatterChapter 2

ChemistryThe study of matter and how it

changesMatter = has mass and takes up

spaceSimplest form of matter = AtomsDifferent types of atoms =

elements. (they cannot be broken down)

CompoundsAtoms of more than one

element bound together. Ex: H2O, C6H12O6, NaCl, HCl

Molecule = smallest unit that exhibits all the properties of that substanceEx: H2O, C6H12O6

Chemical FormulasChem symbols and numbers tell

us how many of each element is in a compound

Example: The chem formula for table sugar is C12H22O11. Each molecule contains 12 carbon atoms, 22 hydrogen atoms, and 11 oxygen atoms.

Types of Matter

Pure Substance = matter with fixed composition and definite properties

Mixture = Combination of more than one pure substance.

Ex: Grape Juice is a mixture of pure substances such as water, sugar, vitamins, etc…

Types of Pure Substances

Elements – listed on the Periodic Table

Compounds – Combination of elements

Types of MixturesHeterogeneous – subs are NOT

uniformly mixedExample: mixture of flour and water

Homogeneous – subs are evenly mixed (looks the same throughout) AKA Solution

Example: mixture of salt and water – the salt dissolves in the water

Liquid Mixtures Miscible – liquids are able to dissolve

into each other Homogeneous mixture of liquidsGasoline = homo. mixture of 100

compounds

Immiscible – liquids are NOT able to dissolve into one anotherHeterogeneous mixture of liquidsOil and water will not mix

BuoyancyThe force with which a more

dense fluid pushes a less dense subs up.

Ice is less dense than water.

Archimedes’ Principlethe buoyant force on an object equals

the weight of the fluid displaced by the object

Bernoulli’s PrincipleAs the velocity of a fluid

increases, the pressure exerted by the fluid decreases

Explains why planes can fly

Mixtures with GasesMany gases form mixtures

with other gases or liquidsEx: Air – homo. mixture of gases

Ex: Soda – homo. mixture of gas and liquid

Ex: Foam – mixture of gas and liquid

Kinetic TheoryAll matter is made up of atoms or

molecules.

The atoms/molecules are always in motion.

More massive atoms/molecules move slower.

States of MatterSolid LiquidGasPlasma – most common state in

the universeVery fast moving charged particlesMakes up stars

SolidsDefinite volume and shape –

“Rigid”

Atoms are held together with strong forces

Particles vibrate in fixed position

LiquidsDefinite volume, indefinite shape

Atoms slide past one another

Viscosity = property that describes the resistance of a fluid to flow

Gases Indefinite shape and volume

Atoms not very attracted to each other

Free motion

Exert pressure

EnergyAbility to cause changes in the

states of matter (phase changes)

Evaporation Liquid GasEnergy is absorbed (by a liquid causing

atoms to move faster until they break away from the liquid surface to form a gas.)

More Phase ChangesCondensation

Gas LiquidReleases energy (energy is given from

the gas to the surroundings)

SublimationSolid GasEnergy is absorbedEx: CO2 (s) CO2 (g) Dry Ice

Insert picture from p. 382 chemistry book

Phase Change Diagrams

Show the changes of state for any subs.

Show the temperatures where the phase change occurs

Is more energy used to convert ice to water or water to steam?

Insert phase diagram on p. 49

Heat of FusionAmount of heat required to

melt a solid at its melting point

Different for every subs.

Heat of VaporizationAmount of heat needed to

change a liquid into a gas at its boiling point

Also different for every subs.

State ChangesNo change in the composition or

mass of the atoms.Law of Conservation of Energy

Energy cannot be created or destroyed

Law of Conservation of MassMass cannot be created or destroyed

Properties of GasesThermal Expansion = gas

molecules become farther apart as temp increases

Pressure = Force exerted per unit area of a surfaceUnit: atmospheres (atm)Pressure around us comes from air

molecules

Boyle’s Law Relates pressure (P) and volume (V)

As P increases, V decreases

P1V1 = P2V2

Inverse relationship

Charles’s Law

Relates V and temperature (T)

As T increases, V increases

V1 = V2

T1 T2

Direct relationship

Combined Gas LawIncludes P, V, and T

P1V1 = P2V2

T1 T2

Chemical Properties Methods that a subs can use to

transform into a new subs with different properties

Reactivity = ability of one subs to combine with another subs

Ex: flammability, corrosiveness, rusting, explosiveness,

Physical PropertiesCharacteristic of a subs that can

be observed without changing the subs

Ex: Melting point (s l) Boiling point (l g)

DensityPhysical property The amount of mass in a

certain volume

D = m/VUnits = g/mL or g/cm3

Chemical ChangesChange that occurs to form a

new subs. (product has a different composition.)

Ex: Digesting food, steel rusting, food burning, gasoline combusting, milk souring

Signs a Chemical Change Occurred

OdorColor changeGas produced (bubbles)Solid producedTemperature change (hot or cold)

Physical ChangesChange that does NOT alter the

composition of the subs.

Melting chocolate, freezing water, tearing paper, chopping food, dissolving sugar

Dissolving = water molecules surround the other molecules and spread them out evenly.