 2.1
Chapter 2
Classification of
Matter
– Properties of Matter
 Pure
substance – has exactly
same composition (made of
the same atoms or molecules)
 Elements (atoms & molecules)
 Compounds (molecules)
Elements
 About
118 elements
 Cannot be broken down into a
simpler substance
 Contains only one kind of atom
 Arranged on periodic table
 Back
cover of Book
Elements
 Different
elements are made
from different types of atoms
 Represented
1st
2nd
by symbols
letter always capitalized
letter never capitalized
Compounds
 Made
of 2 or more elements
in fixed proportions
(molecules)
Examples:
H20, C6H12O6, NaCl, H2O2, O2,
MgCl2
Molecule: is a building block of a
compound, made of 2 or more atoms
 Compounds can be broken down
 Ex. Burning Sugar, Electrolysis
 Properties of the compound differ
from the properties of the elements it
is made of

Properties of Na, Cl, NaCl
Property
Sodium (Na)
Chlorine (Cl)
NaCl
State (room
temp)
solid
gas
solid
Color
Silver
Yellow
White
Toxic
somewhat
Yes
No
Explosive w/ O2
Yes
No
No
Crystal Structure
No
No
Yes (cubic)
Odor
No
Yes
No
Edible
No
No
Yes

Sodium
Chlorine
Salt
Mixtures
Properties of Mixtures
1.
2.
3.
4.
5.
6.
2 or more pure substances
mixed together
Parts are physically mixed, NOT
chemically combined
Not in fixed proportions
Not evenly distributed
Keeps some properties from
each substance (ingredients)
Can be separated
Types of Mixtures
 Heterogeneous
mixtures
 “hetero” = different
 Not the same throughout
 Can see the different parts
 Examples: sand, concrete,
hamburger, stew
Types of Mixtures
 Homogeneous
 “homo”
mixtures
= same
 Evenly mixed
 Appears the same throughout
 Cannot see different parts
 Examples: salt water, soda,
lemonade, stainless steel
Solutions

Solution: is a homogeneous mixture with substances
dissolved in a liquid

Solvent: is usually a liquid that dissolves another
substance (water is the universal solvent) Ex. water,
alcohol, paint thinner

Solute: is the substance being dissolved

Ex. Salt, sugar, baking soda,
 Solutions
can be separated by
distillation
 Examples:
salt water, punch,
tea, coffee, power-ade, soda
Suspensions
 Heterogeneous
 Separates
mixture
over time
 Suspensions
can be separated by
filtration
 Example:
dressing
dirt and water, Italian
Colloids
 Homogeneous
mixture
 Cloudy, creamy
 Cannot see through
 Do not separate into layers
 Cannot filter
 Examples: fog, milk, lotion
2.2 Physical Properties
 Any
characteristic observed
without changing composition
of the substance
 Example: mass, volume,
weight, density, color, size,
shape, texture, odor,
Examples
 Viscosity
 High
– resistance to flowing
Viscosity =Oil, honey, syrup
 Low Viscosity = H20, alcohol, etc.
 Conductivity
– ability to allow heat
and electricity to flow
 Metals
are good conductors
 Non-metals are insulators
 Malleability
– ability of a solid to
be hammered into a thin sheet
 Gold,
Aluminum, copper, lead,etc.
 Density
– the amount of mass
squeezed into the volume (space)
 used
to test the purity of a
substance
 D=M/V
 All elements have unique densities

Density hot water vs. cold water DEMO
 Density
is the property that
determines whether an object
floats or sinks
 List of common densities
 Hot water vs. cold water
 Melting
point – the temperature
when a solid becomes a liquid
 Water
– 0o C or 32o F
 Also the freezing point
 Boiling
point – the temperature
when a liquid becomes a gas
 Water
– 100o C or 212o F
 Different substances have diff.
boiling and melting points
Using Physical Properties
 To
identify materials
 Solving
crimes
 To
choose materials for
specific purposes
 Manufacturing
 Construction
products
 To
separate mixtures
 Filtration
– separates materials
based on size of particles
Heterogeneous
(Suspensions)
 Distillation
– separates
substances in solution using
boiling points
Homogeneous
(Solutions)
2.3 Chemical Properties
 Chemical
property – describes a
substance’s ability to change
composition (new substance)
 Flammability
– ability to burn
 Flaming hand DEMO
 Reactivity
– ability to combine
chemically with other substances
 All elements are reactive, EXCEPT
the Noble gases
 Elements react to become stable
Example: rust, tarnish (oxidation)
Recognizing Chemical
Changes
3
types of evidence
 Change
in Color
Ripening
banana
 Production
Vinegar
and baking soda
 Formation
Lemon
of a Gas
of a Precipitate
juice and milk - curdling
Chemical or Physical
Change?
 Chemical
– composition of
matter changes – forms
new substance
 Physical – composition of
matter stays the same