Ch. 2

1
MATTER
yes
no
Can it be physically separated?
MIXTURE physically combined
PURE SUBSTANCE
no
yes
no
yes
Can it be chemically decomposed?
Is the composition uniform?
Homogeneous Mixture (solution)
Heterogeneous Mixture
Compound
Element
Colloids
Suspensions
Immiscible
Miscible
Courtesy Christy Johannesson www.nisd.net/communic
ationsarts/pages/chem
2
III. Chemical Formulas - The chemical symbol
and the numbers indicating the atoms contained in
the basic unit of a substance
3
Note First letter of an element symbol is
capitalized. If there is a second letter in the
symbol it is lower case. Ex N, O, Ca, Ag
4

• shows how many atoms of each element are in the
  basic unit of a substance.
• Number of atoms is written as a subscript to the
  right side of the symbol
• Ex C6H12O6
• means 6 atoms of C
• 12 atoms of H
• 6 atoms of O
• 24 total atoms
• No subscript means 1 atom present
• Ex H2O not H2O1

5

• Number in front shows the number of molecules.
• Ex 2 AgNO3
• 2 molecules
• 2 atoms of Ag
• 2 atoms of N
• 6 atoms of O
• Total of atoms 10

6
Ex Ca(OH)2 1 molecule 1 Ca 2 O
2 H 5 total atoms
7
Ex 2 Ca3(PO4)2 2 molecules 6 Ca 4
P 16 O total of atoms 26
8
Ex C16H10N2O2 (indigo dye) 1 molecule of
indigo 16 C 10 H 2 N 2 O total of
atoms 30