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)
Ionic bonding
Ionic bonding involves 3 steps
• 1) loss of an electron(s) by one element,
• 2) gain of electron(s) by a second element,
• 3) attraction between positive and negative
e–
1)
Na
2)
Cl
3)
Na+
Na+
Cl–
Ions
Since ions are formed as a results of the
movement of electrons,
ionic compounds will conduct electricity when
in solution
Covalent bonding
If two atoms have approximately the same
pull on electrons, they share the electrons
(forming a “covalent” bond)
Rules for naming
Ionic compounds
MONATOMIC IONS (single atom ions)
• Metal ions form positive ions : CATIONS
• Metal (+ ion) comes 1st Names
• Identified simply by the elements name
• Negative ions : ANIONS
• Drop the ending and replace with -ide.
Example: sodium chloride
• Do not capitalized unless starting a sentence
Binary Compounds
(compounds composed of two elements)
• Total number of positive charges and negative
charges must be equal
• Use valence electrons to balance
name of cation
name of anion
• Example: magnesium bromide
Mg2+
Br1need 2 Br1-
MgBr2
• Some metals form 2 or more cations with
different charges
• As before, positive metal comes first
• The charge (valence) of the metal is indicated
in brackets using roman numerals
• the anion ends in –ide
• e.g.
Fe2+ is iron(II)
Fe3+ is iron(III)
Element
(charge)
Name
Cu (1,2)
copper (I) , copper(II)
Fe (2,3)
iron(II), iron (III)
Pb (2,4)
lead(II), lead(IV)
Sn (2,4)
tin (II), tin (IV)
Co (2,3)
cobalt (II), cobalt (III)
Cr (2,3)
chromium(II) chromium(III)
Mn (2,3)
manganese(II), manganese(III)
Hg (1,2)
mercury (I), mercury (II)
Polyatomic Ions
• 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
• You should note that compounds with polyatomic
ions have names ending in -ate or -ite not -ide
• Note that most are negative, except ammonium
• 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
Practice naming
Ionic compounds
Give formulae & name: Ca + I, O + Mg, Na + S
= Ca2I1 = CaI2 = calcium iodide
= Mg2O2 = MgO = magnesium oxide
= Na1S2 = Na2S = sodium sulfide
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
CCl4
carbon tetrachloride
P2O3
diphosporus trioxide
IF7
iodine heptafluoride