Chapter 7
Chemical Formulas and Chemical Compounds
Section 7.1
Chemical Names
and Formulas
Recall that a chemical formula indicates
the relative number of atoms of each
kind in a chemical compound
Example: C6H12O6
 This type of compound is called a
hydrocarbon, because it is comprised of
carbon and hydrogen
 Example 2: Al2(SO4)3

Monatomic Ions
Monatomic ions- ions formed from a
single atom

Commonly groups 1 and 2, 15, 16, 17


Lets label the oxidation number (charge) on the
periodic table
Elements in the d-block form +2 or+3,
sometimes +1 or +4 or a combination of
different charges

Unfortunately they do not fit a pattern
Naming Monatomic Ions
Nomenclature- naming system
Cations (metals) keep their name
Anions (nonmetals) drop their ending
and change it to –ide

Examples: Fluorine
Nitrogen
Binary Ionic Compounds
Binary compounds- compounds
composed of two different elements
In a binary ionic compound, the total
number of positive charges must equal
the total number of negative charges
The cation (metal) is always written first
Examples
Give the formulas for the following
compounds:
Sodium and chlorine
 Magnesium and bromine
 Zinc and iodine
 Aluminum and oxygen
 Lithium and nitrogen
 Magnesium and oxygen


Now go back and name them
The Stock System of
Nomenclature
Some elements, such as iron, form 2 or
more cations with different charges
You use a Roman numeral to indicate
an ions charge
The numeral is enclosed in parentheses
and placed immediately after the metal
name
Many of the transition metals require
this
Here are some of the more
common ones:
Copper
Chromium
Cobalt
Iron
Lead
Manganese
Mercury
Nickel
Tin
Vanadium
Examples:
Write formulas for the following:
Copper (II) and bromine
 Iron (II) and oxygen
 Lead (II) and chlorine
 Iron (III) and oxygen
 Manganese (VII) and oxygen

Name the following:
CuO
CoF
SnI4
FeS
CuCl2
PbCl2
Cr2O3
Compounds Containing
Polyatomic Ions
Compounds containing polyatomic ions
are named in the same manner as
binary ionic compounds
The only difference is when more than
one polyatomic ion is present in a
compound, the entire ion is surrounded
by parentheses
Examples:
Write formulas for the following:
Sodium sulfate
 Calcium nitrate
 Ammonium nitrate
 Potassium perchlorate
 Lithium nitrate
 Aluminum sulfate
 Lead (II) hydrogen carbonate

Name the following:
Ca(OH)2
 KClO3
 FeCrO4
 KClO
 NH4OH

Naming Binary Molecular
Compounds
Unlike ionic compounds, molecular
compounds are composed of individual
covalently bonded units, or molecules
2 rules are followed:
1. Use prefixes to tell how many atoms of
each element are in the compound
* exception- do not use a prefix on the first
element if there is only one atom
2.
The second element always ends in the
suffix -ide
Molecular Prefixes
1 mono
2 di
3 tri
4 tetra
5 penta
6 hexa
7 hepta
8 octa
9 nano
10 deca
Examples
Name the following:
N2O4
 C2H6
 P4H10
 BrI

Give the formula for the following
compounds:
Dihydrogen monoxide
 Phosphorus trihydride
 Nitrogen dioxide
 Carbon tetrachloride
 Sulfur hexafluoride

Acids and Salts
Acid- a distinct type of molecular
compound

Always includes hydrogen
Binary acid- acids that consist of 2
elements, usually a hydrogen and one
of the halogens or group 16 elements
Oxyacids (ternary acids)- acids that
contain hydrogen, oxygen, and a third
element, usually a nonmetal
Rules for binary acids
Binary acids have the prefix hydro- and the
suffix -ic.
The stem word depends on the element that
is involved
Examples:
*one exception: HCN





HCl
HF
HBr
Hydroiodic acid
Hydroselenic acid
Rules for ternary acids
Use the name of the negative ion as the
root word
If the ending on the negative ion is –ite
(chlorite) change the ending from –ite to
–ous acid (HClO2-chlorous acid)
 If the ending on the negative ion is –ate
(chlorate) change the ending from –ate to
–ic acid (HClO3-chloric acid)

Exceptions
If the negative ion contains sulfur or
phosphorus, the root word is sulfur or
phosphor.

H2SO3

H3PO4
Salts
Salt- an ionic compound composed of a
cation and the anion from an acid

Sometimes the word hydrogen is given as
bi- in the anion name

Example: HCO3- hydrogen carbonate or
bicarbonate