Ionic and Covalent
Compound Naming
4.2
Ionic Compounds: - are made
up of positive and negative ions
arranged in a crystal structure.
Covalent Molecules: - are made
up of atoms sharing electrons.
Name of an ionic compound = cation anion-ide
e.g.1: magnesium and oxygen
cation anion-ide
Magnesium ox + ide
Magnesium oxide
e.g.2: what is the name of Ca3N2?
Ca = calcium; N = nitrogen
Drop the end of the anion and add –ide
Calcium nitride
e.g.3: What is the name of BaCl2?
Barium chloride
Calcium nitride
Remember: positive charges
must = negative charges
e.g.1: What is the formula for
magnesium phosphide?
e.g.2: What is the formula for
calcium oxide?
Calcium is Ca2+ Oxygen is O2–
1 Ca2+ ion & 1 O2– ion
Magnesium is Mg2+
Phosphorous is P3–
Lowest common multiple of 2
and 3 is 6
3 Mg2+ ions & 2 P3– ions (6
+ve’s & 6 –ve’s)
Magnesium phosphide = Mg3P2
Calcium oxide = CaO
Examples on whiteboard (unless we get a
projector by the time this class comes!):
– Lithium nitride
– Barium sulphide
Multivalent: some transition
elements have more than one
charge.
Roman numerals are used
after the metal name to
indicate which ion was used
e.g. What is the formula
for manganese (III)
sulphide?
This manganese is Mn3+.
Sulphur is S2Lowest common multiple of
3 and 2 is 6
2 Mn3+ ions and 3 S2- ions
Mn2S3
What is the name for TiF4?
Titanium can be
4+
Ti
or
3+
Ti
Fluorine is F–
From the ratio in the formula you can find
out it is Ti4+
1 Ti4+ ion and 4 F– ions
Titanium (IV) fluoride
are made up of several atoms joined together by
covalent bonds
The whole group has a + or – charge, not
individual atoms.
e.g. What is the formula of sodium sulphate?
Na+ and SO42–
Na2SO4
e.g. 2: What is the name of the compound KClO?
K+=potassium, ClO-=hypochlorite
Potassium hypochlorite
e.g. 3: What is the formula for Calcium nitrate?
Ca2+ and NO3Ca(NO3)2
* Note the brackets around NO3 show there are two of the nitrate
ions present
Prefixes are used before the atom name
to indicate the number of atoms in the
molecule.
Examples:
CO = carbon monoxide, CO2 = carbon
dioxide
Write the most metallic atom (furthest left)
first, then add -ide to the end of the
second atom’s name
What is the name of the molecule Si3P6?
Trisilicon hexaphosphide
What is the chemical formula for the
molecule trinitrogen tetrachloride?
N3Cl4
To determine whether a compound is ionic or
covalent:
Examine the formula
Ionic compounds start with a metal or the
ammonium ion
Covalent compounds start with a non-metal