naming ionic and covalent compounds

1. Naming Compounds
What's in a name? That which we call a rose
By any other name would smell as sweet."
- William Shakespeare, Romeo and Juliet (II, ii)

2. Background: valences and formulas
• We can determine the formula of a compound
by completing Lewis diagrams or via “valence”
• Valence is “the number of electrons an atom
must gain, lose, or share to complete its octet”
• For representative elements valence starts at
1 (1), climbs to 4 (4) and falls back to 1 (7)
• By knowing the valence of elements you can
determine the formula of compounds
• E.g. what compound would form from C + S?
Step 1 - write valences: C 4S 2
Step 2 - cross down valences: C2S4
Step 3 - simplify formula: CS2

3. Ionic compounds (metal with 1 valence)
Rules for naming
• Names end in -ide. Example: sodium chloride
• Metal (+ ion) comes 1st (not chlorine sodide)
• Use the group valence for nonmetals
• Do not capitalize the compound unless
starting a sentence
Give formulae & name: Ca + I, O + Mg, Na + S
= Ca2I1 = CaI2 = calcium iodide
= Mg2O2 = MgO = magnesium oxide
= Na1S2 = Na2S = sodium sulfide

4. Write the correct formula for these
a) Al + Br AlBr3
b) K+S K2 S
c) Zn + O ZnO
d) Mg + N Mg3N2
e) C + Cl CCl4
f) Cu + O CuO or Cu2O

5. Learning Check
Complete the names of the following binary
compounds:
Na3N sodium ________________
KBr potassium ________________
Al2O3 aluminum ________________
MgS _________________________

6. Multiple valence: Latin naming
• When the metal in an ionic compound is multi-
valent there are 2 methods: Latin or IUPAC
• Latin is older (not useful for some compounds)
• As before, the name ends in -ide & + is first
• The metal is named with it’s Latin or English
root and ends in -ic or –ous to denote valence
• E.g. Cu1 is cuprous, E.g. Cu2 is cupric
• Lower = ous, Higher = ic (lower & higher charge)
• Give formulas and Latin names for:
Cu2 + Cl = Cu2Cl1 = CuCl2 = cupric chloride
Co2 + Cl = Co2Cl1 = CoCl2 = cobaltous chloride
For latin naming: know rules, remember Hg is
an exception, do not memorize Latin names

7. Element English Latin Name Higher Lower
(valence) name valence valence
Metals that have and use latin names
Cu (1,2) Copper Cuprum Cupric Cuprous
Fe (2,3) Iron Ferrum Ferric Ferrous
Pb (2,4) Lead Plumbum Plumbic Plumbous
Sn (2,4) Tin Stannum Stannic Stannous
Metals that do not have latin names
Co (2,3) Cobalt - Cobaltic Cobaltous
Cr (2,3) Chromium - Chromic Chromous
Mn (2,3) Manganese - Manganic Manganous
Metals that have latin names but use english root
Hg (1,2) Mercury Hydrargyrum Mercuric Mercurous

8. Multiple valence: IUPAC naming
• Name ends in -ide, positive/metal comes first
• The valence (charge) of the metal is indicated
in brackets using roman numerals
• E.g. Cu1 is copper(I), Cu2 is copper(II)
• Numbers refer to charge not to #s of atoms

9. Write the correct name and formula
• Cu2+Cl
• Zn2 + Cl
• Co2+Cl
• Hg+S (do both)
a) Cu2+Cl = Cu2Cl1 = CuCl2 = copper(II)chloride
b) Zn2+Cl = Zn2Cl1 = ZnCl2 = zinc chloride
c) Co2+Cl = Co2Cl1 = CoCl2 = cobalt(II) chloride
d) Hg+S = Hg1S2 = Hg2S = mercury(I) sulfide
d) Hg+S = Hg2S2 = HgS = mercury(II) sulfide

10. Learning Check
Complete the names of the following binary
compounds with variable metal ions:
FeBr2 iron (_____) bromide
CuCl copper (_____) chloride
SnO2 ___(_____ ) ______________
Fe2O3 ________________________
Hg2S ________________________

11. Compounds containing polyatomic ions
• So far we have given valences to single
atoms Li1O2 → Li2O
• Groups of atoms can also have valences
Li + O
• “Polyatomic ions” are groups of atoms that
interact as a single unit.
• E.g. OH1, (SO4)2.
• Ba3(PO4)2 = barium phosphate
• Naming compounds with polyatomic ions is
similar to naming other ionic compounds
• You should note that compounds with polyatomic
ions have names ending in -ate or -ite not -ide
• Note that most are negative, except ammonium

12. Naming with Transition Metals
Name Balanced Ion Formula
Pairs
Lead (IV)
Hydroxide
Iron (III)
Carbonate
Copper (II)
acetate

13. Naming with Transition Metals
Name Balanced Ion Formula
Pairs
Lead (IV)
Pb+4 + 4(OH-)
Hydroxide
Iron (III)
2Fe+3 + 3CO3-2
Carbonate
Copper (II)
Cu+2 + 2C2H302-1
acetate

14. Naming with Transition Metals
Name Balanced Ion Formula
Pairs
Lead (IV)
Pb+4 + 4(OH-) Pb(OH)4
Hydroxide
Iron (III)
2Fe+3 + 3CO3-2 Fe2(CO3)3
Carbonate
Copper (II)
Cu+2 + 2C2H302-1 Cu(C2H302)2
acetate

15. Write the name
• Ca(OH)2
• Cu(SO4)
• NH4(NO3)
• Co2(CO3)3
a) Calcium hydroxide
b) Copper (II) sulfate
c) Ammonium nitrate
d) Cobalt (III) carbonate

16. Naming covalent compounds
1 mon • -ide ending, each element has
o • prefix refers to # of atoms - not valence
“prefix”
2 di
N2O4 = dinitrogen tetroxide
3 tri
• Exception: drop mono for first element
4 tetra CO2 = carbon dioxide
5 pent • The first vowel is often dropped to
6 a
hexa avoid the combination of “ao” or “oo”.
7 hept CO = carbon monoxide
P4O10= tetraphosphorus decoxide
(monooxide)
8 a
octa SO2= sulfur dioxide (doxide)
9 nona • Name: CCl4, P2O3, IF7
1 deca

17. Write and name the following
covalent compounds (IUPAC)
CCl4
carbon tetrachloride
P2O3
diphosporus trioxide
IF7
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