Naming ionic and
covalent compounds
Memorize these rules well
before your session.
Introduction
to chemistry
Issued by startmyclass. (SMC)
Below are some of the rules that students need to
keep in mind while naming ionic and covalent
compounds. Remember! there are different set
of rules for ionic and covalent compounds. We
shall first look at the rules we should remember
while naming Ionic compounds.
😃
Rules for ionic compounds.
Mono-atomic cations have no change. (e.g Na+ can be simply
called a sodium ion.)
Mono-atomic anions have the suffix -ide at the end. (e.g F- can be
called fluoride ion.)
There are two important cases for ionic compounds.
1. Cations that can only assume a single oxidation state will follow
the following naming template: cation + anion (with the suffix ide.)
Although transition metals don’t follow these rules, we have some
exceptions including Zinc, Al, and Ag.
KI
Potassium iodide.
MgCl2
Magnesium chloride.
Al2(CO3)3
Aluminium carbonate.
NH4OH
Ammonium hydroxide.
Remember some polyatomic ions like OH and CO3 have special names
and can used as such without adding the suffix -ide. Student can find the
list of common polyatomic ions at the end of these notes.
2nd case: When cations can adopt more than one oxidation
states, it wise to mention their oxidation states within the name.
This is for all transition metals and larger group 3A and 4A metals.
They will follow the following naming template : cation (oxidation
state in roman numerals) + anion (with suffix- ide).
FeBr2
Iron (II) bromide.
Co(OH)3
Cobalt (III) hydroxide.
PbO2
Lead (IV) oxide.
Pb2O3
Lead (III) oxide.
Rules for covalent compounds.
Name the less electronegative element first, followed by the name of the
more electronegative element with the suffix -ide.
Many covalent compounds have common names like water, ammonia
etc.
Mention the number of each type of atom with the greek prefixes.
1
mono
2
di
3
tri
4
tetra
5
penta
6
hexa
7
hepta
8
octa
REMEMBER ! mono is not to be used for the 1st atom in the
formula.
CO
Carbon monoxide. (no mono used
for the 1st atom in the formula.)
CO2
Carbon dioxide.
PCl3
Phosporus trichloride.
CCL4
Carbon tetrachloride.
N2F4
Dinitrogen tetrafluoride.
Whenever you are given a compound to name, determine
whether its an ionic compound or a covalent compound. Use the
rules accordingly.
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How to determine whether a compound is ionic or covalent in nature.
Ionic compounds.
1. Will have large
electronegativity difference.
Usually a metal is paired with a
non-metal.
Covalent compounds.
1. Will have small
electronegativity difference.
A non-metal with another nonmetal or a metalloid.