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
Water –
MP is 0°C
Gallium – MP is 30°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
How can you tell the difference?
• Clues of a Chemical
Change:
– Transfer of energy: Heat
and Light
– Formation of Gas
– Formation of Precipitate
– Change in Color
– Solid that settles out of
liquid
Chemical Reaction
2H2 + O2  2H2O
Reactants
Products
Law of Conservation of Mass:
Mass of Reactants = Mass of 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:
H2
N2
O2
F2
Cl2
Br2
I2
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
H2
Oxygen – Colorless Gas
O2
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?