Naming Ionic compounds
• Binary Compounds
– Name the cation – always comes first
– Indicate the charge on the cation if necessary
• Transition metals can form more than one
cation
• Roman numerals or Latin names are used
to identify the ion
– Name the anion
• Use the beginning of the anion followed by
the suffix “ide”
Write the formula for the ionic compound that will form
between Ba2+ and Cl−.
Solution:
1. Balance charge with + and – ions
2. Write the positive ion of metal first, and the
negative ion
Ba2+
Cl−
Cl−
3. Write the number of ions needed as
BaCl2
subscripts
Names of Variable Metallic Ions
Write the correct formula for the compounds
containing the following ions:
1. Na+, S2a) NaS
b) Na2S
c) NaS2
2. Al3+, Cla) AlCl3
b) AlCl
c) Al3Cl
3. Mg2+, N3a) MgN
b) Mg2N3
c) Mg3N2
These elements REQUIRE Roman Numerals because they
can have more than one possible charge:
any metal except alkali metals, alkaline earth metals,
Ag, Zn, Cd, and Al
(You should already know the charges on these!)
Or another way to say it is: Transition metals and the metals in groups
4A and 5A (except Ag, Zn, Cd, and Al) require a Roman Numeral.
FeCl3
CuCl
SnF4
PbCl2
Fe2S3
(Fe3+) iron (III) chloride
(Cu+ ) copper (I) chloride
(Sn4+) tin (IV) fluoride
(Pb2+) lead (II) chloride
(Fe3+) iron (III) sulfide
Latin Names
• Copper
– +1 cuprous
– +2 cupric
• Iron
– +2 ferrous
– +3 ferric
• Lead
– +2 plumbous
– +4 plumbic
• Tin
– +2 stannous
– +4 stannic
• Mercury
• +1 mercurous
• +2 mercuric
• Ternary compounds – more than 2 elements
– Name the cation
– Name the anion (usually a polyatomic ion)
• Polyatomic ions
– The most common form of the ion uses the suffix
“ate”
– Adding one oxygen to the common form adds the
prefix “per”
– Removing one oxygen from the common form
changes the suffix to “ite”
– Removing an oxygen from the “ite” form adds the
prefix “hypo”
Naming Molecular Compounds
• Adding a hydrogen to any polyatomic ion adds the
prefix “bi” and a positive one to the charge
• Replacing an oxygen with sulfur in any polyatomic ion
adds the prefix :thio”
• Name the first element
– Use prefixes to indicate the number of atoms of that element
(mono is never used on the first element)
• Name the second element changing the ending to “ide”
– Use prefixes to indicate the number of atoms of that element
• 1 – mono
• 2 – di
• 3 – tri
• 4 – tetra
• 5 – penta
• 6 – hexa
• 7 – hepta
• 8 – octa
• 9 – nona
• 10 – deca
Naming Acids
• You recognize that the compound is an acid when it
begins with hydrogen
– Binary acids
• Acids with only two elements
• Prefix is always hydro
• Name the second element using the suffix “ic”
– EX: HCl
• Hydrochloric acid
– H3P
• Hydrophosphoric acid
• Ternary acids – the name depends on which
polyatomic ion is in the acid
– If the polyatomic ion ends in “ate”, the acid ends in “ic”
– If the polyatomic ion ends in “ite” the acid ends in “ous”
– Examples
• HClO3
– Chloric acid
• HClO2
– Chlorous acid
• HClO4
– Perchloric acid
• HClO
– Hypochlorous acid