Classifying Matter
Pure Substances:
Matter that can be represented by a
chemical formula.
 Two categories of pure substances are
elements and compounds.

Element - Na
Compound - NaCl
Elements

The simplest form
of pure substances.

Most consist of
single atoms while
others exist as
molecules.
Gold
 All are listed on the (Au)
periodic table.
Copper
(Cu)
More Elements
 There
are 7 diatomic elements
 (all molecules since bonded to each
other)
 Hint: On the periodic table, start
with #1, Hydrogen, go to #7 and
make a 7.
 H2, N2, O2, F2, Cl2, Br2, I2
Allotropes

Different molecular
forms of an element in
the same physical state
(solid, liquid or gas).
 O2 and(ozone) O3
(both gases);
 Carbon: diamond,
graphite and
buckyballs.(all solids)
Allotropes of Sulfur
Orthorhombic
Monoclinic
Compounds

Pure substances made of 2
or more different elements
chemically combined.
 H20; CO2; C6H12O6
Al(OH)3 and
Ca(OH)2
Mixtures
A
collection of 2 or more pure
substances physically mixed
together that cannot be
represented by a chemical
formula.
Homogeneous Mixtures

The mixed substances
are evenly distributed
and the same
throughout. They are
also called solutions.
 Particles will not
settle out.
 Eg: Salt water
(saline), syrup, air,
gasoline (top, bottom, Copper (II) Chloride Solution
left and right look the
same)
Alloys

Alloys are homogeneous mixtures
between 2 solids.
 Bronze (Cu & Sn); Brass (Cu & Zn);
14-Karat Gold (Au & Ag); Steel (Fe, C, &
other metals)
Courtesy of Mr. Allen, El
Diamante HS, Sciencegeeks.com
Heterogeneous Mixtures
 The
mixed
substances are
not evenly
distributed
Eg: OJ with
pulp; salad;
everything
pizza.
Types of Heterogeneous Mixtures

Suspension: a
heterogeneous
mixture that
settles upon
sitting. Key
phrase is shake
before use
 Large particles,
sometimes visible
to the naked eye.

E.g. clay in water,
some medicines,
OJ with pulp,
ketchup.
Colloid

Colloid: a
suspension that
does not settle
 Microscopic
particles (so it
looks the same
throughout, but it
is NOT.
 Will not be crystal
clear.
 Ex. Milk, Jello

Observe Tyndall Effect
(light beam bounces off
suspended microscopic
particles to show they
are present)
Molecular Pictures of Substances
Classify each example as the specific type of matter on the first
line and if it is an atom, molecule or both on the second line.
Separation Techniques

Mixtures can be separated by
physical or chemical means.
 With physical means, the substances
are not changed by the process.
 The substances you start with mixed
together are the substances you are
left with separately.
Physical Separation Techniques

Filtration:
 Distillation is used to
Separates a solid
separate substances
from a liquid by
with different
using filter paper
boiling points.
and a funnel.
 Example: separation
 The liquid that
of salt water or the
passes through the
separation of alcohol
filter paper is called
and water.
the filtrate.
Separation of a Mixture
Distillation
Physical Separation Techniques

Evaporating: A liquid is evaporated away
leaving the remaining component.
 Decanting: A liquid is poured off leaving
the remaining solid. (Pasta and water)
 Centrifuge: A mixture is spun and based
on density the mixture breaks into different
parts (This is done with your blood to
separate it into the plasma, white blood
cells and red blood cells).
Centrifuge
Separation Techniques (Cont.)


With chemical
separation, the
original
components are
lost.
Examples of
chemical
separation are
chromatography
and electrolysis

Chromatograpy is used to
separate the parts of a
solution in dyes and
pigments.

Electrolysis is a process in
which electrical energy is
used to separate a
compound. The
electrolysis of water
produces oxygen and
hydrogen.
Separation of a Mixture
The components of dyes
such as ink may be
separated by paper
chromatography.
Density

Density: The ratio of the mass of an object to its
volume (physical intensive property)
 Density = Mass (g)/Volume(mL or cm3)
D=M
For all liquids 1mL=1cm3
V
Water has a density of 1.0 g/mL (Must Memorize)
Therefore, if a substance has a density greater than
1g/mL it will sink in water and if its density is
less than 1g/mL it will float in water
Note: For WATER ONLY: 1g = 1mL= 1cm3
Density Problems

Ex. 1 Silicon has a mass
of 12.0 g and a volume
of a 5.17 cm3. What is
its density?
12.0 g/5.17 cm3 =
2.32 g/cm3 or 2.32 g/mL
Water and copper shot both float on
mercury because mercury is more dense.
Density Problems (Cont.)

Ex. 2 Aluminum has a volume of
20.0 mL and a density of 2.70 g/mL.
What is its mass?
2.70 g/mL =
Xg .
20.0 mL
2.70g/mL
x 20.0 mL =
54 g
Density Problems (Cont.)
 Ex.
3 Mercury has a mass of
22.0 g and a density of 13.6 g/cm3.
What is the volume?
 13.6 g/cm3 = 22.0 g
x cm3
13.6 x = 22.0
x = 1.62 cm3 or 1.62 mL
Density Practice (You Try)

1. What is the density of a sample with a mass
of 14.52 g and a volume of 10.6 mL? Would it
float or sink in water?

Answer: Density = Mass/Volume so 14.52 g/ 10.6mL=
1.37 g/mL; It would sink since the sample’s density is
greater than water’s density of 1g/mL.

2. What is the volume of a 8.30 g sample of
Aluminum with a density of 2.70 g/mL?
 Answer: 2.70 g/mL = 8.30 g
x mL
2.70 x = 8.30
x= 3.07 mL or cm3