This presentation covers Chapter 2 on the general topic of Matter and Change. Substances or mixtures? Chemical or physical changes?

1. Chapter 2 – Matter & Change
By Kendon Smith – Columbia Central HS – Brooklyn, MI

2. Chapter 2 – Matter and Change
I. Properties of Matter
1. Matter is defined as anything that has
mass and volume.
a. Mass: the amount of matter an object
contains.
b. Volume: the amount of space an object
occupies.

3. 2. Describing Matter
a. Extensive Property: property that depends
on the amount of matter in a sample
b. Intensive Property: property that depends
on the type of matter in a sample
Examples: Identify the following properties of
a sample as extensive or intensive.
Mass: ___ Color: ___ Flammability: ___
Volume: ___ Density: ___ Melting Point: ___

4. 3. Identifying Substances
a. Substance: matter that has uniform and
definite composition.
- Uniform means it is the same throughout
the sample.
- Definite composition means chemically
the same all over the planet!
Examples: Water? Sand? Copper? Salt?

5. b. Physical Property – a quality or condition
of a substance that can be measured or
observed without changing a
substance’s composition.
Examples:
color, solubility, odor, hardness, density,
melting point, boiling point, physical state,
mass, volume

6. 4. States of Matter
A. Solids – form of matter with definite shape
and definite volume
- Particles are packed tightly together
B. Liquids – form of matter with indefinite
shape and definite volume
- Liquids take the shape of their container
- Particles in liquids are almost incompressible
- Particles in liquids usually expand slightly
when heated.
- Particles in a liquid are close together, but
can flow past each other

7. 4. States of Matter
C. Gases – form of matter with indefinite
shape and indefinite volume
- Particles in gases very far apart
compared to liquids and solids.
- Particles in gases are easily compressed,
pushing closer together.
* Vapors – Gaseous substances that are
liquids or solids at room
temperature.

8. States of Matter

9. 5. Physical changes – alter a material without
changing its chemical composition
- Physical changes can be classified as
reversible or irreversible
a. Reversible changes: melt, freeze, boil,
condense
b. Irreversible changes: break, split, grind,
cut, crush

10. II. Mixtures
1. Mixture – a physical blend of two or more
substances.
a. Homogeneous mixture:
- completely uniform composition,
- parts are not readily distinguished
Examples – brine, gatorade, jello,
creamy peanut butter

11. II. Mixtures
1. Mixture – a physical blend of two or more
substances.
b. Heterogeneous mixture:
- not uniform composition
- parts are readily distinguished
Examples – sand and water, a salad,
jello w/ fruit, chunky peanut butter

12. 2. Solution – a homogeneous mixture - may
be solid, liquid, or gas
Examples – brine, sugar water, air,
stainless steel
3. Phase – any part of a sample that with
uniform composition and properties
How many phases?
Brine = ___ Oil/Vinegar = ___
Air = ___ Sand/Water = ___

13. 4. Separating Mixtures: Mixtures can be separated
using physical means.
a. Decant, or pour off, a liquid layer.
Ex. Oil/Water Mix
b. Filtration: Separates solids from liquids with their
dissolved particles.
c. Distillation – Boil a liquid to become a vapor and
condense it back.
d. Magnet – Pull out magnetic particles from a
mixture.
e. Sorting - Physically separating by appearance
Ex. size, color, shape

14. III. Elements and Compounds
1. Distinguishing elements and compounds
a. Elements – the simplest form of matter with
a unique set of properties
- Elements are the basic building blocks of
all other substances.
- Cannot be separated into simpler
substances by chemical means.
Examples: hydrogen, oxygen, carbon

15. III. Elements and Compounds
b. Compounds – two or more elements
chemically combined in a
fixed proportion
- Compounds can only be separated into
simpler substances by chemical means,
but not by physical means, like mixtures.
Examples: water (H2O)
sucrose (C12H22O11)
carbon dioxide (CO2)
sugar water???

16. III. Elements and Compounds
c. Chemical change: produces matter with a
different composition
- Bonds are broken to chemically separate
elements.
- New bonds are formed to chemically join
elements.
Example 1: sucrose (table sugar)
HEAT
C12H22O11 12 C + 11 H2O

17. III. Elements and Compounds
c. Chemical change: produces matter with a
different composition
- Bonds are broken to chemically separate
elements.
- New bonds are formed to chemically join
elements.
Example 2: water (electrolysis)
ELECTRICITY
2 H2O 2 H2 + O2

18. III. Elements and Compounds
2. Properties of Compounds
a. Properties of compounds can be quite
different from those of their component
elements.
- Each compound is a new, pure substance
with unique properties.

19. a. Properties of compounds can be quite different
from those of their component elements.
Example 1: Water – made of hydrogen and oxygen
Properties: Hydrogen: Extremely flammable gas
Oxygen: Gas that supports combustion
Water: Non-flammable liquid!

20. a. Properties of compounds can be quite different
from those of their component elements.
Example 2: Table Salt – made of sodium and chlorine
Soft, silvery metal that
Properties: Sodium: reacts violently with water
Poisonous, yellowish gas
Chlorine:
white, crystalline solid
Sodium chloride: that we must eat!

21. III. Elements and Compounds
3. Distinguishing Substances and Mixtures
a. Fixed composition – the material is a
substance
b. Variable composition – the material is a
mixture
KEY CONCEPT!
* Homogeneous mixtures look like
substances because both appear to be
made of one kind of matter.

22. Matter
Substance Can be Mixture
(definite (variable
composition) physically composition)
separated
Element Compound Homogeneous Heterogeneous
(uniform; called (not uniform;
a solution) distinct phases)
Can be chemically
separated

23. Matter
Substance Mixture
(definite (variable
lo
composition) ok composition)
s
lik
e
Element Compound Homogeneous Heterogeneous
(uniform; called (not uniform;
a solution) distinct phases)

24. 4. Symbols and Formulas
a. Chemical symbol – one or two letters
which represent each element
- First letter of the symbol is always
capitalized, while the second letter is
always lower case.
- Most symbols are derived from the Latin
names for the elements.

25. Name Latin Symbol
Sodium Natrium Na
Potassium Kalium K
Antimony Stibium Sb
Gold Aurum Au
Silver Argentum Ag
Iron Ferrum Fe
Lead Plumbum Pb
Mercury Hydrargyrum Hg
Tungsten Wolfran W
Copper Cuprum Cu

26. b. Chemical formulas – use symbols to show
the relative proportions of elements in a
compound.
- Because compounds have fixed
compositions, the chemical formula
for a compound is always the same.
- Subscripts are written next to the symbol
and give us the proportion
of each element in the compound.
i. The number one is never written as a subscript,
it is assumed!
ii. If a subscript is written outside parenthesis, it
multiplies the proportions of all the
elements inside the parenthesis.

27. Examples: What are the proportions of elements in
each of the following compounds?
1. Table sugar (sucrose) =
12 carbons, 22 hydrogens, 11 oxygens
2. C2H5OH (ethanol) =
2 carbons, 6 hydrogens, 1 oxygen
3. Al(OH)3 =
1 aluminum, 3 oxygens, 3 hydrogens
4. (NH4)2CO3 =
2 nitrogens, 8 hydrogens, 1 carbon, 3 oxygens
5. Co3(PO4)2 =
3 cobalts, 2 phosphorus, 8 oxygen

28. IV. Chemical Reactions
1. Chemical Changes: always involve a
change in chemical composition
a. The ability of a substance to undergo chemical
change is called a chemical property
b. Words that signify chemical change:
burn, rot, rust, decompose, ferment, explode,
corrode
c. Chemical properties can only be observed while a
substance is undergoing a chemical change,
during what is called a chemical reaction

29. IV. Chemical Reactions
2. Chemical reaction – one or more
substances change into new substances
a. Reactant – a substance present at the start
of the reaction (BEFORE!)
b. Product – a substance produced during a
reaction (AFTER!)
REACTANTS PRODUCTS

30. 3. Some basics rules for writing chemical
reactions:
a. Reactants written on the left and products
on the right with an arrow between.
b. Reactants are separated from each other
with a + symbol. Same for products.
c. The arrows always points toward the
products and can be read as “yields”
or “produces” or “changes into”.

31. Example 1 - Oxidation of Iron: The reaction
between iron and oxygen yields
iron oxide.
Iron + Oxygen Iron oxide
Example 2: During combustion, ethanol reacts
with oxygen and produces carbon
dioxide and water.
ethanol + oxygen carbon dioxide + water

32. 4. Recognizing Chemical Changes
a. Clues that a chemical reaction has taken
place:
1. Energy is absorbed or released
- hot or cold!
Examples: Burning wood – gives off heat
Cook food – absorbs heat
*Note: There are energy changes during
changes of state, which are only
physical changes, so energy
change alone is not sufficient!

33. a. Clues that a chemical reaction has taken
place:
2. Change in color = new chemical has been
formed!
3. Change in odor = smells are caused by
chemicals!
4. Production of gas = you will see bubbles!
5. Production of a precipitate = a solid formed
from liquid mixtures.

34. 5. Conservation of Mass
a. Law of Conservation of Mass:
mass cannot be created or destroyed
b. In a chemical reaction, the mass of all the
reactants must equal the mass of all the
products.

35. Examples:
10g of ice melt = 10g of water (phys. change)
2.5 kg of wood burn & produce 0.4 kg of ash?
- 2.1 kg of water vapor, carbon dioxide, and
other gases released to air
1.5 grams of magnesium ribbon burns and the
ashes weigh 2.1 grams
- combined with oxygen in the air to produce
magnesium oxide