Compounds

1
Compounds Molecules

• Counting atoms

2
Counting atoms in a chemical fomula

• Add up the subscripts.
• Ca3P2 5 atoms

• Dont forget the invisible 1s
• CaCO3 Ca1C1O3 5 atoms

• Multiply anything inside parentheses by the
  subscript on the outside.
• Ba(NO3) 1 Ba, 2 N, 6 O 9 atoms

2
2
3
Practice
How Many Atoms?

• AlPO4
• MgC2O4
• Pb(MnO4)2
• AgI
• Li2S
• B2(S2O3)3

6
7
11
2
3
17
4
Binary Compounds

• Writing Chemical Formulas

5
Writing Chemical Formulas

• The metal (or ion) is always written first.

• The nonmetal (or ion) is always written last.

• The subscripts tell how many of each atom or
  polyatomic ion you have.

6
Writing Chemical Formulas

• EXAMPLE Write the chemical formula for the ionic
  compound containing Al and Br.

1 determine the charges
3
-1
Al
Br
7
Writing Chemical Formulas

• 2 cross the charges. Do not carry the sign
  (/-) and do not write the number 1.

3 simplify if needed (lowest common
factor) Not needed here
3
1
Al
Br
8
Writing Chemical Formulas

• You try Mg and S

Mg2S2
Simplify - MgS
9
Writing Chemical Formulas

• USING POLYATOMIC IONS
• Na and OH-1

Na1
OH-1
NaOH
Ca and PO4-3
Ca2
PO4-3
Ca3PO42 ???
10
Writing Chemical Formulas

• If the polyatomic ion gets a subscript you MUST
  use parentheses.
• Ca3(PO4)2

11
Naming Ionic Compounds

• With Main Group Metals
• Name the Ion Name the metal.
• Name the - Ion - Name the nonmetal, changing the
  ending to ide

12
Naming Ionic Compounds

• Examples

MgO
magnesium oxide
CaCl2
calcium chloride
13
Naming Ionic Compounds

• With Polyatomic Ions
• Name the ion or polyatomic ion
• Name the ion or polyatomic ion

Examples
sodium nitrate
NaNO3
aluminum sulfate
Al2(SO4)3