Matter and Changes in Matter
Dr. Childs
Fall, 2005
Science Laboratory
Matter
Matter
Matter is everything that we see and
many of the things we don’t see (as air). By
definition matter has mass and occupies space.
Matter is classified into two major categories:
- Pure substances
- Mixtures
Pure silver
Brass
(mixture of
copper & zinc)
Matter
Matter can be changed. These changes may involve
physical changes in which the composition of the
matter is not changed or chemical changes in which
the composition is changed.
Candle burning
Ice melting
Pure Substances
Pure substances:
- contain the same type of particles throughout.
- have a definite composition.
- may be either elements or compounds
sodium chloride
NaCl
sodium
Na
chlorine
Cl
Types of Matter
Matter
Substance
Element
Compound
Mixture
Homogeneous
Heterogeneous
Elements & Compounds
Elements & Compounds
• An element is a pure substance that cannot be
broken into anther substance (by ordinary
chemical means). Composed of only a single
type of atom.
• A compound is a pure substance composed by
two or more elements
How about some examples?
Elements
• Many things are made of elements. For example,
aluminum is used for foil and for building cars and
trailers.
Note: If its on the periodic table its an element!
Gold
Elements
Sulfur
Lead
Oxygen
Hydrogen fuel
Sodium lamp
Elements
magnesium wheels
silicon sealant
chromium wheels
lithium grease
titanium clubs
carbon fiber
Compounds
Compounds are formed when two or more atoms of two or more
elements combine chemically (bonding!).
- fixed ratio of elements with a definite formula
- separation into elements requires chemical procedures
Water H2O
Note: Compounds are NOT on the periodic table.
Compounds
table sugar
C6H12O6
table salt
NaCl
Carbon dioxide
CO2
Nitrous oxide
N2O
Sodium hydroxide
NaOH
rust
Fe2O3
Epsom salts
MgSO4
Mixtures
Mixtures
Mixtures are materials made up of two or more
pure substances.
Mixtures can be separated by physical means based on
physical properties:
evaporation
filtration
floating
magnets
Mixtures may be either
homogeneous (solutions)
heterogeneous
Mixtures
Mixture
Homogeneous
Heterogeneous
Evenly mixed
Unevenly mixed
Mixtures
Homogeneous mixture of metal are “alloys”. Alloys
include brass, steel, and white gold.
Homogeneous mixtures in which one substance is
dissolved in another is a “solution”. Solutions include
coffee, IV fluids, and fog.
Homogeneous Mixtures
Examples:
Sea water
Coffee
Blood
Air
Brass
White gold
water and salt
coffee, sugar, cream
red cells, white cells, plasma
nitrogen, oxygen, CO2
copper, zinc
gold, silver, platinum
Homogeneous Mixtures
Corn
flakes
Brass
Coffee
jello
Blood
colored
water
Salt water
Heterogeneous Mixtures
Examples:
raisin bran
chocolate chip cookie
tossed salad
pizza
granite
Italian dressing
cereal with raisins
lettuce, tomatoes, carrots
pizza with meat, cheese
feldspar, mica
oil, water, spice
Heterogeneous Mixtures
Italian dressing
Raisin Bran
Tossed salad
Chocolate Chip
cookie
Granite
Marble
Muddy water
Separating Mixtures
filtration
evaporation
salt ponds
evaporation
distillation
Separating Mixtures
chromatography
electrophoresis
centrifugation
Physical and Chemical
Changes
Physical & Chemical Properties
Be sure to know the difference between:
- Physical properties &
chemical properties
- Physical changes &
chemical changes
Physical Properties
Physical properties can be observed without a
chemical reaction.
Examples:
color:
density:
state:
magnetism:
texture:
water is clear, table salt is white
aluminum has a density of 2.7 g/cm3
oxygen is a gas at room temperature
iron is attracted to magnet
gold is shiny
Physical Properties
What are some physical properties of:
sulfur?
lemonade?
dish soap?
Physical Changes
In a physical change substances are not altered
chemically, including:
state changes
solid  liquid
liquid  gas
mixing or separating
adding sugar to coffee
evaporating sea water for salt
tearing paper
Physical Changes
State Changes
liquid  solid
“freezing”
water to ice
liquid  gas
“evaporation”
water to steam
gasoline to vapor
solid  gas
“sublimation”
dry ice to CO2
freezing
evaporation
sublimation
Physical Changes
State Changes
solid  liquid
“melting”
ice to water
ice cream melting
gas  liquid
“condensation”
ice to water
condensation
melting
Physical Changes
Physical changes may involve changing shape but not composition;
Breaking glass
Sawing wood
Planing wood
Chemical Properties
Chemical properties:
The properties of an element or compound
in a chemical reaction
Examples:
gasoline is flammable
water can be separated by electrolysis
neon is inert
Chemical changes
Chemical reactions:
- yield new substances
- usually cannot be easily reversed
- may either require or release energy (light, heat, etc.)
Sugars in wood may be split by burning. Combustion
yields new substances: CO2 and water and heat and
light energy.
Chemical Changes
Fireworks
Toasting bread
Candle burning
Combustion
Digesting food
Chemical Changes
bread rising
photosynthesis
food cooking
batteries
rusting
The End