2.1 Properties of Matter• Define and prove the Law of Conservation of Matter• Describe a substance according to its physical and

chemical properties.• Distinguish between extensive and intensive properties.• Describe the six states of matter.• Identify physical changes to matter.• Identify the chemical properties of a substance.• Describe chemical changes and differentiate them from

physical changes.• Use various visual clues to identify whether a chemical

reaction is taking place.

2.2 Classification of Matter• Define a mixture and understand why

mixtures are different than pure substances.• Classify mixtures as homogeneous or

heterogeneous• Classify liquids as a solution, suspension,

colloid, or alloy• Describe several ways to separate mixtures.• Distinguish between elements and

compounds.

Classifying MatterClassifying Matter

Matter

ElementsCompound

sMixtures

• Scientists classify matter according to make-up.

Elements and Compounds

An element is the simplest form of matter and has a unique set of properties.

A compound contains two or more elements chemically combined in fixed proportions.

Compounds can be broken down, elements cannot.

ElementsElements

• Simplest pure substance – fixed composition.

• Pure substance is made of only one material. Same throughout. Referred to as homogeneous matter.

• Are made of alike atoms, which are the basic building blocks of matter.

• Represented by chemical symbols - H, O, Al, Cu, Au.

• 118 elements organized in the periodic table in squares called an element key.

CompoundsCompounds

• Two or more elements chemically combined.

• Represented by chemical formulas.

• Examples: H2O, CO2, NaCl, C12H22O11

• Molecules are the smallest natural unit of a compound or diatomic element. A molecule is made up of two or more atoms chemically combined.

Pure Substances: Elements are Composed of identical

atoms

Chlorine gas

Sodium metal

2 or More Elements Combine to Produce a Compound

Chlorine gas +

Sodium metal

+

=

=

Sodium Chloride

MixturesMixtures

• Two or more substances mixed together but not chemically combined.

• Has unlike parts and a composition that varies from sample to sample.

• Properties:

– Sub. in a mixture keep their separate identities.

– Sub. can be present in any amount.

– Sub. can be separated out by physical means.

MixturesMixtures

Mixtures

Homogeneous

Heterogeneous

Mixtures: Variable combination of two or more

substances:

Homogeneousuniform throughout

Heterogeneousnot uniform throughout

Used to describe any part of a sample with uniform composition and properties

Heterogeneous: 2 or more phases Homogeneous: 1 phase

PhasePhase

SolutionsSolutions• A homogeneous mixture.

• One substance dissolves in another. Solutions remain constantly & uniformly mixed.

•Solute and Solvent

•Particles are smaller than 1 nm in size

•Particles do not settle

•Particles pass through filter paper

Examples: lemonade, soda, ocean water, antifreeze, metal alloys

A homogeneous mixture combining two or more metals to maximize the benefits of each.

Ex. Gold Jewelry: 14 kt Gold (Gold for shine, Silver for strength)

AlloyAlloy

ColloidsColloids• A homogeneous mixture.

• Mixed together but not dissolved.

• Appears cloudy. Scatters light.

•Particles are 2 – 100 nm in size

•Particles do not settle

•Particles pass through filter paper

•Usually not transparent (cloudy)

• Examples: milk, cool whip, toothpaste, lotions, fog, smoke, Jello.

Heterogeneous Mixture Particles settle to the bottom unless

constantly stirred Particles are greater than 100 nm Not transparent, must be mixed Ex: Paint, Chocolate Milk,

SuspensionSuspension

Composition of MatterComposition of Matter

E le m e nt C o m p ou nd

P u re S ub s ta n ce

S o lu tion C o llio d

H o m o ge n eo us

S u sp e ns ion

H e te ro ge n eo us

M ix tu re

M a tte r

2.3 Changing Matter

• Describe how chemical potential energy relates to heat and work.

• Describe the law of conservation of energy and how heat flows between system and surroundings during both endothermic and exothermic processes.

• Use the specific heat equation to perform calculations that relate mass, specific heat, change in temperature, and the amount of heat absorbed or released.

Thermochemistry

Chemical Potential Energy

• the energy stored in the chemical bonds of a substance

• the kinds of atoms and their arrangement in the substance determine the amount of energy stored in the substance.

AKA: HEAT

If 2 objects remain in contact, heat will flow from a warmer object to the cooler

object until the temperatures are equal.

(A) Object A starts with a higher temperature than object B. No heat flows when the objects are isolated from each other.

(B) When brought into contact, heat flows from A to B until the temperatures of the two objects are the same.

Heat• Symbol = q

• energy that transfers from one object to another because of temperature difference

• Heat always flows from a warmer object to a cooler object.

An Ice Cold Spoon A Hot Spoon

energytransfer

Thermochemistry

• The study of energy changes that occur during chemical reactions and changes of state.

• In any chemical or physical process, energy is neither created or destroyed

• If energy of the system decreases the energy of the surroundings must increase by the same amount so that the total energy of the universe remains unchanged.

Law of Conservation of Energy

The Universe

• Can be divided into 2 “parts”

• System- the part you are investigating

• Surroundings- the rest of the universe

• In a thermo-chemical experiments the region in immediate vicinity of the system are the surroundings.

Units of Heat

calorie

• the amount of energy contained within food

• Quantity of heat required to to raise the temp of 1g of water 1° C

Calorie=Kilocalorie=1000calories

joule

• SI Unit of energy

• Heat changes in chemical reactions are typically measured in joules.

Joule and calorie Conversion Factors

• 1J = 0.2390cal

• 1 cal = 4.184 J

HEATHEAT HEATHEAT HEATHEAT HEATHEAT

Different type of materials may have the same temp, same mass, but different conductivity.

• They are affected by the potential energy stored in chemical bonds or the IMFs holding molecules together

• It is possible to be at same temp (same KE) but have very different thermal energies.

• The different abilities to hold onto or release energy is referred to as the substance’s

heat capacity

The measure of how well a material absorbs or releases heat energy

•Physical property unique to a particular material•The heat capacity depends on both its mass and its chemical composition. •The greater the mass; the greater the heat capacity.• It can be thought of as a reservoir to hold heat, how much

it holds before it overflows is its capacity•Water takes 1 calorie of energy to raise temp 1 °C• Steel takes only 0.1 calorie of energy to raise temp 1 °C

Heat Capacity

Specific Heat

The amount of heat required to raise the temperature of one gram of substance by one degree Celsius.

q = mCT

Calculations Involving Specific Heat

c = Specific Heat

q = Heat lost or gained

T = Temperature change

pq c m T

m = Mass

Table of Specific Heats

Calorimetry

• The precise measurement of heat flow into or out of a system for chemical and physical purposes

• The heat released by the system is equal to the heat absorbed by its surroundings.

• Conversely, the heat absorbed by a system is equal to the heat released by it’s surroundings.

Calorimeter

There are three methods used to transfer heat energy.

• Conduction – transfer of heat through direct contact

• Convection – transfer of heat through a medium like air or water

• Radiant – transfer of heat by electromagnetic radiation