The document summarizes key concepts about matter, including: - Pure substances are classified as either elements or compounds. - Elements contain only one type of atom, while compounds are made of two or more simpler substances. - Mixtures can be heterogeneous or homogeneous based on how evenly distributed their parts are. - Physical properties describe observable characteristics without changing a substance's composition. - Chemical properties involve changes in composition through chemical reactions.

1. Chapter 2
Nina Bartell 8-3

2. 2.1

3. Pure Substance
Matter that always has exactly the same
composition is classified as a pure substance
*every sample of a given substance has the
same properties because a substance has a
fixed, uniform composition
can be classified into two categories-elements
and compounds

4. Elements and Atoms
a substance that cannot be broken down into simpler
substances
an atom is the smallest particle of an element
*an element has a fixed composition because it
contains only one type of atom
no two elements contain the same type of atom

5. Compounds
a substance that is made from two or more
simpler substances and can be broken down
into those simpler substances
The simpler substances are either elements or
other compounds

6. Mixture
*the properties of a mixture can vary because
the composition of a mixture is not fixed
mixtures can be classified by how well the
parts of the mixture are distributed throughout
the mixture

7. Heterogeneous and homogenous
mixtures
Heterogeneous: the parts of a mixture are
noticeably different from one another (sand)
Homogenous: the substances are so evenly
distributed that it is difficult to distinguish one
substance from another(serving spoon-iron,
chromium, and nickel)

8. Solutions/Suspensions/Colloids
*Based on the size of its largest particles, a mixture can
be classified as a solution, suspension, or colloid
Solution: when substances dissolve and form a
homogenous mixture
Able to see through solutions that are liquids because
light passes through them without going in all different
directions
Suspension: heterogeneous mixture that separates into
layers over time

9. 2.2

10. Physical Properties
Any characteristic of a material that can be observed
or measured without changing the composition of the
substances in the material
Used to identify a material, to choose a material for a
specific purpose, or to separate the substances in a
mixture
viscosity, conductivity, malleability, hardness, melting
point, boiling point, and density are all

11. Viscosity
The tendency of a liquid to keep from
flowing, it’s resistance to flowing
Honey has a high viscosity because it is
very resistant but water has a low
viscosity because it is not very resistant

12. Conductivity
A material’s ability to allow heat to flow
would you use a metal or wooden
spoon while stirring soup?
A wooden one because it has low
conductivity so the top of the spoon
doesn’t get hot and it won’t burn you

13. Malleability
The ability of a solid to be hammered
without shattering
Gold is malleable because when
hammered, it doesn’t shatter but an ice
cube is not because if hammered, it
would shatter
Most metals are malleable

14. Melting point
Temperature at which a substance changes
from a solid to a liquid
Melting point for water is 0˚c at sea level

15. Boiling Point
Temperature at which a substance boils
Boiling point for water is 100˚c at sea level

16. Density
Used to test the purity of a substance
Ratio of the mass of a substance to its volume

17. Identifying a Material
1. Decide which properties to test
2. Do tests on the sample of the unknown
3. Compare the results with the data reported
for known materials

18. What are Properties?
They determine which materials are chosen for
what uses

19. Filtration and Distillation
These two terms are common separation
methods
Filtration: a process that separates materials
based on the size of their particles
Distillation: a process that separates the
substances in a solution based on their boiling
points

20. What is physical change?
The change of water from a liquid to a gas
during boiling
This occurs when some of the properties of the
material change but the substances in the
material stay the same

21. Ways of Separating a
Mixture
Distillation
Filtration
Evaporation

22. Distillation
A process that separates two substances in a
solution based on their boiling points
Distillation Apparatus
Unknown Substance
Alcohol Burner

23. Filtration
A process that separates materials based on the
size of particles +/or solubility
filter paper goes inside filter
the mixture is poured into filter paper
the element left in the filter paper is the
substance and the liquid at the bottom is to
purified water (liquid)

24. Evaporation
A process used to isolate a solid dissolved in a
liquid
ex: NaCl+water
Disclaimer: water(liquid) will evaporate+you
won’t be able to isolate a sample of it
mixture is poured into an evaporating dish
which is heated and all that is left is the
dissolved element that is now not dissolved

25. 2.3

26. Chemical Property
Any ability to produce a change in
composition of matter
Changes the composition of the substance
*Chemical properties can only be observed
when the substances in a sample of matter are
changing into different substances

27. Flammability
A material’s ability to burn in the presence of
oxygen
Example: alcohol and water

28. Reactivity
A property that describes how readily a
substance combines with other substances.
Example: Oxygen/Potassium

29. Chemical Change
Occurs when a substance reacts and forms one
or more new substances
*Three common types of of a chemical change:
-change in color -the production of gas -the
formation of a precipitate

30. Precipitate
Any solid that forms and separates from a
liquid mixture

31. REVIEW
QUESTIONS

32. #1 QUESTION
HOW MANY CATEGORIES ARE PURE
SUBSTANCES CLASSIFIED INTO? AND
WHAT ARE THOSE CATEGORIES?

33. #2 QUESTION
WHAT TYPE OF CHANGE DO YOU USE
WHEN YOU WANT THE COMPOSITION OF
THE SUBSTANCES TO STAY THE SAME?

34. #3 QUESTION
WHAT TECHNIQUE WOULD YOU USE TO
ISOLATE A SOLUTION OF SALT AND
WATER?

35. #4 QUESTION
IF BLUE DYE WAS SPILLED ON A SHIRT,
WOULD IT BE A CHEMICAL OR PHYSICAL
CHANGE? WHY?

36. ANSWERS:
#1- Pure substances are classified into two categories,
elements and compounds.
#2-You would use a physical change if you wanted the
composition of the substances to stay the same.
#3-The technique used to isolate a solution of salt and
water would be evaporation.
#4-It would be a chemical change if blue dye was
spilled on a shirt because it changes the color, but also,
it can never come out therefore it adds to the object.