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)
BACKGROUND:
Prior to the 1700s, there was no systematic
method of naming compounds. Substances
were named in variety of ways, such as the
use of compounds, the property of the
compound, or the source of the substance.
These names give little, if any, information
about the composition of the compound.
Common Name: Quick lime/ Lime
IUPAC Name: Carbon Oxide
Chemical Formula: CaO
Use or property: Neutralizing
acidified lakes
Common Name: Baking Soda
IUPAC Name: Sodium
bicarbonate
Chemical Formula: NaHCO3
Use or property: Making baked
goods rise
Common Name: Laughing gas
IUPAC Name: Dinitrogen
monoxide
Chemical Formula: N2O
Use or property: Used in dentistry
as anaesthetic
Common Name: Table salt
IUPAC Name: Sodium Chloride
Chemical Formula: NaCl
Use or property: Enhancing
flavour
Common Name: Quartz sand
IUPAC Name: Silicon dioxide
Chemical Formula: SiO2
Use or property: manufacturing
glass
Background: valences and formulas
• Valence is “the number of electrons an atom
must gain, lose, or share to complete its octet”
• For representative elements valence starts at 1
(alkali metals), climbs to 4 (group 4) and falls
back to 1 (halogens)
• 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:
C4S2
Step 2 - cross down valences: C2S4
Na
O
AlBrStep
K
S
ZnO
Mg
N
CCl
2
3
simplify
formula:
CS
3
2
3 2
4
2
a) Al,Br b) K,S c) Zn,O d) Mg,N e) C,Cl f) Na,O
Ionic compounds
•
•
•
•
Rules for naming
Names end in -ide. Example: sodium chloride
1. Write metal name first then non metal
2. Change the ending of the non metal to “ide”
3. Do not capitalized 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
Multiple Valence
• Some metals have more than one valence.
• For these metals, you can use the Latin or
IUPAC method
• Latin is older (not useful for some
compounds)
• IUPAC is more commonly used
Latin naming
• As before, the metal name if written first and
the non metal ends in -ide
• 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
• Give formulas and Latin names for:
Cu2 + Cl = Cu2Cl1 = CuCl2 = cupric chloride
Cu1 + Cl = Cu1Cl1 = CuCl = cuprous chloride
Element
(valence)
English
Latin Name
Higher
Lower
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
High with the “i”
Low with the “o”
Name the following:
• FeCl2
– Fe -> +2
– Cl -> -1
–Ferrous chloride
• CuO
– Cu -> +2
– O -> -2
- Cupric oxide
IUPAC naming
• Metal comes first, ending of non metal is “ide”
• The valence of the metal is indicated in
brackets using roman numerals
• E.g. Cu1 is copper(I), Cu2 is copper(II)
• Numbers refer to valences not to #s of atoms
• Try: Cu2+Cl, Zn2 + Cl, Co2+Cl, Hg+S (do both)
Cu2+Cl = Cu2Cl1 = CuCl2 = copper(II) chloride
Zn2+Cl = Zn2Cl1 = ZnCl2 = zinc chloride
Co2+Cl = Co2Cl1 = CoCl2 = cobalt(II) chloride
Hg+S = Hg1S2 = Hg2S = mercury(I) sulfide
Hg+S = Hg2S2 = HgS = mercury(II) sulfide
Compounds containing polyatomic ions
• So far we have given valences to single atoms
Li1O2  Li2O
Li + O
• Groups of atoms can also have valences
• “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
• Put the metal name first, then the name of the
polyatomic second.
• You should note that compounds with polyatomic
ions have names ending in -ate or -ite not -ide
• Name: Ca(OH)2, CuSO4, NH4NO3, Co2(CO3)3
Compounds containing polyatomic ions
Ca(OH)2
CuSO4
NH4NO3
Co2(CO3)3
- calcium hydroxide
- copper(II) sulfate
- ammonium nitrate
- cobalt(III) carbonate
Naming covalent compounds
1 mono
2 di
3 tri
4 tetra
5 penta
6 hexa
7 hepta
8 octa
9 nona
10 deca
• -ide ending, each element has “prefix”
• prefix refers to # of atoms - not valence
N2O4 = dinitrogen tetroxide
• Exception: drop mono for first element
CO2 = carbon dioxide
• The first vowel is often dropped to
avoid the combination of “ao” or “oo”.
CO = carbon monoxide (monooxide)
P4O10= tetraphosphorus decoxide
SO2= sulfur dioxide (doxide)
• Name: CCl4, P2O3, IF7
Write and name the following
covalent compounds (IUPAC)
CCl4
carbon tetrachloride
P2O3
diphosporus trioxide
IF7
iodine heptafluoride
Write the formulas for the
following covalent compounds
(IUPAC)
C2Cl4
dicarbon tetrachloride
P5O2
IF8
pentaphosphous dioxide
iodine octafluoride