Unit 2
Unit 2 - Matter
Classify a sample as homogeneous or heterogeneous
Classify a sample of matter as a pure substance or
mixture based on the number of elements or
compounds in the sample.
Explain how a solution, a colloid, or a suspension
are different.
Classify a substance as an element or compound using
its chemical formula.
Classify a sample as homogeneous or heterogeneous
based on uniformity of material.
•
Matter is what makes up everything
in our universe.
•
When we determine the mass of
something, we are quantifying the
amount of matter.
•
Matter can be found in 3 states or
phases (Solid, Liquid and Gas)
•
The smallest unit of Matter is the
ATOM!!!
•
When two or more atoms are
combined in a certain way, the
result is a compound.
• Element  atom
• Compound  molecule
•
Elements and compounds are both
classified as pure substances
•
Pure Substance: has a fixed
composition; Either an element or a
compound
1) Element: Matter composed of
identical atoms
2) Compound: Matter composed of 2 or
more elements; elements are
combined in a fixed ratio
•
•
Properties of compounds are
different from the separate
elements
Ex. NaCl
•
Physical combinations of 2 or more
pure substances.
•
The substances are simply mixed
together; They ARE NOT chemically
combined
•
Ex. – mix salt and pepper
•
Combination of substances in which
different materials can be easily
distinguished.
• Ex. Granite
•
Two Types
• Suspension
• Colloid
Salad
•
Heterogeneous mixture containing
a liquid in which visible particles
settle.
• Ex. Vinaigrette dressing muddy water
•
Heterogeneous mixture of medium
sized particles, but not heavy
enough to settle out.
• Ex. Milk
paint
•
Uniform combination of substances
•
Blended evenly throughout
•
Also called solutions
•
Very small components
•
Particles are so small they will never
settle.
• Ex. Kool-aid
Coffee
MATTER
yes
MIXTURE
yes
Is the composition
uniform?
Homogeneous
Mixture
(solution)
no
Can it be separated by
physical means?
PURE SUBSTANCE
no
Heterogeneous
Mixture
(colloid or
suspension)
yes
Can it be seperated by
a chemical reaction?
no
Compound
Element
(Molecules)
(Identical atoms)
•
Physical Properties: characteristics
of a material that can be
determined without changing the
identity of the material
•
Ex. color, shape, size, density,
melting point, boiling point,
flexibility
•
Chemical Properties:
characteristics of a substance that
indicate whether it can undergo
certain chemical changes
•
Ex. flammability, reaction to light
•
Physical Changes: changing only
physical properties
•
Ex.
• changing size (crushing,
breaking, cracking.)
• changing shape
• changing state (boiling, melting,
freezing, condensing.)
•
Chemical Changes: change of one
substance to a different substance
with different properties
•
Ex. Rotting, burning, cooking,
forming bubbles or solids in a liquid,
rusting
•
Identify the following as a physical changes or
chemical change.
1) Baking soda and vinegar produce CO2,
2)
3)
4)
5)
6)
H2O, and sodium acetate
A burning candle
Melting wax
Boiling water
An antacid dissolves in water and
produces gases
Add Kool-Aid powder to water
•
Law of Conservation of Mass: In any
physical or chemical change,
matter is neither created nor
destroyed; It is conserved
•
Ex: A log burns; the matter left
behind or produced is ash, gases,
and smoke. The mass of all of these
products equals the mass of the
log.
- Separation in general is done
based on physical properties.
- Investigate properties of the
material to determine a
separation method.
- Fe (Iron), Co (Cobalt), and Ni
(Nickel) are the only three
naturally magnetic elements
- These can be separated from a
mixture using a magnet
- Way to separate an insoluble
solid from a liquid
- Use filter paper to trap the solid
- Way to separate liquids based
on differences in boiling points
- Way to separate a solution – ie.
separating a dissolved solid from
water
- Heat the solution, often in an
evaporating dish; the water
evaporates to steam and the solid is
left as a crystal
- Way to separate a solid from a
liquid
- Use a centrifuge to spin the
sample – the solid (precipitate)
goes to the bottom and the liquid
left on top is called the
supernatant
- Separates components on
ability/speed in travelling across a
surface
- The surface could be paper, gel,
or some other medium