Extensive vs. Intensive Properties Extensive Properties: Depends on amount Ex: Mass, Volume Intensive Properties: Depends on type of matter Ex: Hardness

States of Matter Solid: Definite Shape Definite Volume Incompressible Liquid: Indefinite Shape Definite Volume Not Easily Compressed Gas: Indefinite Shape Indefinite Volume Easily compressed

Candle Lab Turn in: Problem, Hypothesis, Observations, and Conclusion. Procedure Obtain a candle, matches, a piece of string, toothpick, and tongs. Record observations (for both extensive properties and intensive properties) for the candle (unlit). List the states of matter present. Light the candle. Observe and record for 3 minutes. List the states of matter present while the candle is burning. Which state of matter is actually burning? – Light the piece of string, record observations. – Is the wax or the wick burning? What proof do you have to support your answer? Use your observations from this step and the previous step. – Try using a 1/2 toothpick as a wick. Place it in the wax, far away from the regular wick. Light the toothpick. Record observations. What is the role of the wick in the candle? How does it help to keep the candle lit?

When you light a candle, you melt the wax around the wick… Solid  Liquid The wick absorbs the liquid wax and pulls it upward. The wick needs to be naturally absorbent to do this, that is why the toothpick didn’t work The heat from the flame vaporizes the wax… Liquid  Gas It is the vapor that is burning not the solid wick. That is why the wick doesn’t burn as fast as the string.

Substance Matter with uniform and definite composition Would two samples of a substance have the same intensive properties? Extensive?

Physical Physical Property: Can be observed without changing the substance composition – Ex: Hardness, Color, Conductivity, Malleability, Melting Point, Boiling Point Physical Change: Properties of the material may change, but the COMPOSITION does not Gallium – MP is 30°C Water – MP is 0°C

Chemical Properties Chemical Property: Can ONLY be observed by changing the substance composition – Ex: Burn, rot, rust, decompose, ferment, explode, corrode Chemical Change: The COMPOSITION of matter ALWAYS changes Also called a chemical reaction

– Formation of Gas – Formation of Precipitate – Solid that settles out of liquid How can you tell the difference? Clues of a Chemical Change: – Transfer of energy: Heat and Light – Change in Color

Chemical Reaction Law of Conservation of Mass: Mass of Reactants = Mass of Products 2H 2 + O 2  2H 2 O Reactants Products

Element Simplest form of matter with a unique set of properties

Special Elements Some elements can only exist as diatomic elements - they can’t be by themselves – Ex: H 2 N 2 O 2 F 2 Cl 2 Br 2 I 2

Compound Contains 2 or more elements chemically combined in a fixed proportion Can be broken down to simpler elements during chemical reactions

Compounds Properties are different from the elements that they are made of – Ex: Sugar - Sweet, White, Solid Carbon – Tasteless, Black, Solid C Hydrogen – Colorless Gas H 2 Oxygen – Colorless Gas O 2

Mixtures Physical blend of 2 or more things 2 Types: – Heterogeneous: composition is not uniform – Homogeneous: composition is uniform Can be separated physically

What is the difference between a mixture and a compound?