Chapter 2: ME - Properties of Matter
SECTION 1: MATTER HAS OBSERVABLE PROPERTIES
A. Physical properties describe a substance
1. Physical Properties – characteristics of the object
 observed without changing identity of substance
 color, shape, size, volume, mass, texture, senses
melting point
electrical conductivity
color
density
boiling point
thermal conductivity
odor
hardness
2. Density – measure of the amount of matter present in a given volume of
substance
 DENSITY = MASS / VOLUME
Do: calculating density PG 43
3. Physical changes – change in any physical property of a substance without changing the
substance itself
 Breaking piece of clay in half
 Stretching a rubber band
 Change in a substance’s state of matter – water to vapor
 Cutting paper
(SHOW: Transparency #14 on wool)
B. Chemical properties describe how substances form new substances
1. Chemical properties – reaction under certain conditions
 characteristics which are exhibited as one substance is chemically transformed into
another.
 Wood to ashes (combustibility)
 Iron – rusts
 Silver, bronze, copper – tarnishes
Chemical Changes – change of one substance into another
 Chemical change affects the substance
 Combination of atoms in original substances rearrange to make new
2. Signs of a chemical change
 Production of an Odor – egg rotting, smell after thunderstorm
 Change in Temperature – logs burning, breaking of bonds takes energy (cooler)
More bond making – heat
 Change in Color – fruit when ripens,
 Formation of Bubbles – antacid tablet in water ,
 Formation of a Solid – precipitate (2 liquids combine to for solid particles)
 Light is emitted – fireflies, deep sea creatures
Chapter 2: ME - Properties of Matter
SECTION 2: CHANGES OF STATE ARE PHYSICAL CHANGES
Where does the dew come from?
Air is made of a mixture of different gases, including water vapor.
Some of the water vapor condenses – or becomes a liquid – on the cool grass
and forms a droplet of liquid water.
A. Matter can change from one state to another
 Matter is found in three states – solid, liquid, and gas
 Substance itself does not change
 Arrangement of the molecules and space between them causes change
 Physical changes
B. Solids can become liquids, and liquids can become solids.
1. MELTING – process by which a solid becomes a liquid
 Different solids melt at different temps
 Added energy as heat breaks the tight bonds between particles
 MELTING POINT – lowest temperature at which a substance begins to melt
 As solids heat up – molecules vibrate faster
 Molecules break loose and begin to slide past each other – liquid
2. FREEZING – process by which a liquid becomes a solid
 Particles lose energy and bond tightly to form a solid
 As temp is lowered – particles lose energy
 Particles move slowly enough that attraction increases
 FREEZING POINT – temp at which a liquid becomes a solid
C. Liquids can become gases, and gases can become liquids
1. EVAPORATION – process which a liquid becomes a gas
 Fastest moving particles near surface break away from liquid and escape as gas
 As temp increases more particles escape
 SUBLIMATION – solid to a gas (dry ice)
 DEPOSITION – process by which a gas becomes a solid
Chapter 2: ME - Properties of Matter
2. BOILING – process by which a liquid becomes a gas
 If energy as heat is added to liquid, bubbles of gas form throughout
 Unlike evaporation – boiling produces bubbles – dissolved air escaping
 Bubbles contain energetic water molecules that escaped from liquid to form gas
 BOILING POINT – boiling occurs when liquid reaches certain temp
3. CONDENSATION – state where gas becomes a liquid
 Cold can or glass cooled the surrounding air
 As a gas cools it loses energy – greater attraction among particles
 Condensed water forms when warm air containing vapor comes in contact
with a cold surface
 If you cool a gas below its boiling point – almost all of the gas will condense
DO: SECTION 2 REVIEW # 1 – 6 PAGE 55
Chapter 2: ME - Properties of Matter
SECTION 3: PROPERTIES ARE USED TO IDENTIFY SUBSTANCES
Texture, shape and color are physical properties used mostly to identify objects
A. Substances have characteristic properties
 Physical and chemical properties of a substance can be used for identification
 Substances may share properties, no two substances have identical sets
1. Identify unknown substances – Glass of glue OR milk
 Can’t taste and unknown substance
 Rely on color, odor, texture, density, BP, FP
 Scientist rely on Unknown vs. Known - comparing
2. Properties used for identifying substances
DENSITY:
 Densities of wood, plastic and steel are all different
 Compare density of unknown to known for identity
 It IS possible for two substances to have same densities
 Additional data needed for positive ID
HEATING PROPERTIES:
 Substances respond to heat in different ways
 Aluminum and iron are good heat conductors – pots and pans
 Plastic, wood – poor heat conductors
 Measure rate at which a substance conducts heat
SOLUBILITY:
 Measure of how much of a substance dissolves in a given volume of liquid
 EX: sugar and dirt
ELECTRIC PROPERTIES:
 Allowing electric charge to move through
 Copper wire – good conductor
 Plastic and rubber – poor conductors – block the flow
MAGNETIC PROPERTIES:
 Attraction to magnetism
 Iron, Steel (iron inside), Cobalt, and Nickel – magnetic
 Copper, Aluminum, Zinc, Plastic – NON-magnetic
Chapter 2: ME - Properties of Matter
B. Mixtures can be separated by using the properties of the substances in them.
Substances can be separated by using differences in physical properties:
 A magnet will separate materials that have magnetic properties from those that don’t
 EX: Aluminum and steel cans at a recycling center
 Filtration can separate solids from liquids and can separate solids that differ in particle sizes
 EX: tea bags and water and screening dirt
 Evaporation can separate a liquid and the substances dissolved in it
 EX: desalination (removing salt from water), sugar from water
DO: SECTION REVIEW QUESTIONS #1 – 6 PAGE 62