What’s the MATTER, part II

Types of Matter  Pure Substance- Matter with a fixed composition It has distinct properties Examples =elements compounds

Pure substance = Only ONE element or compound (distilled water). Pure substance = Only ONE element or compound (distilled water). Some Examples:

 Mixtures- Most matter is a mixture The composition is not fixed (changes from sample to sample) Two Types – Homogeneous Heterogeneous

Some Examples:  Mixtures are variable combinations of 2 or more pure substances. Heterogeneous – visibly separate phases Homogeneous – Same throughout

Air is a mixture of several gases. Name Formula amount Nitrogen N 2 78 % Oxygen O 2 21 % Argon Ar 1 % Carbon CO % Dioxide

Homogeneous Mixtures  Composition is uniform throughout Solution-  Particle size = 0.01 – 1 nm  Doesn’t settle out upon standing  Can’t be separated by filtering  Doesn’t scatter light  Example = distilled water

Colloid-  Particle size = 1 – 1000 nm  Doesn’t settle out upon standing  Can’t be separated by filtering  Scatters light (Tyndall Effect)  Examples = milk, gelatin, smoke

Heterogeneous Mixtures  The sample varies in composition, properties and appearance  No uniformity  Particle size is greater than 1000 nm  Particles settle out upon standing  Can be separated by filtration  Might scatter light  Examples = soil, trail mix, pond water

Physical vs. Chemical Properties  Every substance has a unique set of properties (characteristics that identify that substance)  Physical Properties- Properties that can be measured without changing the identity and composition of the substance

 Physical Property Examples- Color Odor Density Melting Point Boiling Point Hardness Solubility

Physical Change  A change in matter from one form to another without changing its chemical properties (most can be reversed)  Examples = Change in state Dissolving Compressing

Chemical Properties  Properties that describe the way a substance may change to form other substances  Only observed when a chemical reaction takes place

Chemical Property Examples  Heating to combustion  Reactivity with water or acid  Flammability  Corrosion  Decomposition

Law of Conservation of Mass  In a physical change or a chemical reaction, mass is neither created or destroyed (Antoine Lavoisier)

Is the composition uniform? NoYes MATTER Can it be physically separated? Homo- geneous Mixture (solution) Hetero- geneous Mixture Compound MIXTURE PURE SUBSTANCE Yes No Can it be chemically decomposed? No Yes Suspensions Element Colloids

Putting sand and salt together makes a compound. an element. a mixture. a solution.

Pure Water is a compound. an element. a solution. a mixture. Pure Water is a compound. an element. a solution. a mixture.

Tap Water is a compound. an element. a solution. a mixture. Tap Water is a compound. an element. a solution. a mixture.

Salt (NaCl) is a common substance. Salt is which of these? atom element compound mixture Salt (NaCl) is a common substance. Salt is which of these? atom element compound mixture

Which formulas represent compounds? O 2, H 2 O 2 CO 2, H 2 O H 2, CO 2 H 2, O 2 Which formulas represent compounds? O 2, H 2 O 2 CO 2, H 2 O H 2, CO 2 H 2, O 2

Which of the following is a compound? oxygen water nitrogen air