NAMING COMPOUNDS
Rules for classifying compounds:
1. If a compound contains at least one metal atom and at least one nonmetal atom, the
compound is ionic.
2. If a compound is made up solely of nonmetal atoms, the compound is covalent.
IONIC:
There are three steps to follow when naming ionic compounds:
1. Start with the name of the first atom in the molecule.
2. Take the next atom in the molecule and replace its ending with an “ide” suffix.
3. Putting those two names together gives you the compound’s name.
Examples:
a) NaCl
Sodium chloride
b) K 2 O
Potassium oxide
COVALENT:
These compounds are different because ionic compounds (which consist of nonmetal and a metal
atom) join, they can only form one type of molecule. For example, when Na and Cl become a
compound, the only molecule that they can form is NaCl. They can’t form Na 2Cl or NaCl2 because
the only molecule that will ever be formed between sodium and chlorine is NaCl. Compare this to
covalent molecules (which consist of two nonmetals) where they can form more than one
molecule between two elements. For example, when carbon and oxygen join together, they can
form CO or CO2 . We add prefixes to differentiate them from one another. So, the first would be
carbon monoxide and the second would be carbon dioxide. Below is a table depicting the
prefixes:
Prefix
Meaning
mono
one
di
two
tri
three
tetra
four
penta
five
hexa
six
hepta
seven
octa
eight
nona
nine
deca
ten
Examples:
a) SF6
Silicon hexafluoride
b) K 3 N
Tripotassium nitrate
2
3