Naming Chemical Compounds
“Compound” – pure substance made up of two or more elements chemically combined in
fixed proportions.
Elements in compounds are held together by chemical bonds which form when atoms
gain, lose, or share electrons. If atoms transfer (gain or lose) an electron, then an ionic
compound is formed. If the atoms share electrons then a molecular (covalent) compound
is formed.
Ionic compounds are formed when a metal and non-metal chemically bond.
Example: Table Salt (NaCl)
When dissolved in water they break apart and release charged atoms called ions.
Ex. NaCl + water = solution of ions Na+ (lose an electron) Cl- (gains an electron)
The movement of the charged ions in water allows for the movement of an electrical
current to flow through the solution.
Properties of Ionic Compounds
- good electrical conductivity
- solid at room temperature
- high melting point
Naming Ionic Compounds
1. Metal (positive) ion goes first
2. Non-metal (negative) ion goes second and ends in ide
Example: NaCl Sodium chloride
 Ionic Compound
**one exception to the second rule is if it is a polyatomic ion (ions with many
atoms) **
example: CO3 2- - carbonate
CaCO3 = Calcium Carbonate
3. When an element has more than one ionic charge, use Roman numerals to indicate
which atom is being used.
Example. iron (II) chloride
(Fe2+ ion is used in the compound)
Molecular compounds are formed when two or more non-metals chemically
bond.
Example: Sugar (C12H22O11) or Carbon dioxide (CO2)
Properties of Molecular Compounds
- Poor conductors /good insulators
- solid, liquid or gas at room temperature
- low melting point
When dissolved in water, neutral molecules are released into the solution, which cannot
carry an electrical current.
C12H22O11 (s) + Water  C12H22O11 (aq)
Molecular compounds are named by:
1. Writing the name of the first element.
2. Changing the ending on the name of the second element to –ide.
3. When more than one atom is used in the formula, you start each name with a
prefix.
1 = mono, 2 = di, 3 = tri, 4 = tetra, 5 = penta
example: N2O3  dinitrogen trioxide
4. exception: do not use a prefix if the first element has only 1 atom
example: CO2  carbon dioxide
 Molecular Compound
Common Prefixes
Common Polyatomic Ions
Mono 1
NO3 Nitrate
Di
Tri
Tetra
Penta
Hexa
PO4 Phosphate
CO32- Carbonate
OH - Hydroxide
NH4+ Ammonium
ClO3- Chlorate
2
3
4
5
6
3-
SO32- Sulphate
HCO3- Bicarbonate
NAME THE FOLLOWING
1. NaF
_________________
21. HI _________________
2. NaOH _________________
22. SrS _________________
3. KCl
_________________
23. NaCl ________________
4. FeCl2
_________________________
24. CO __________________
5. CrF2
_________________________
25. HF __________________
6. TiI4
_________________________
26. CoCO3 ______________
7. NH 4OH _______________
27. Cu(HCO3)2 _________________
8. PbO
_________________
28. BeO ________________
9. Mg(NO3)2 _____________________
29. NH4I ________________
10. BaO
30. Ca3(PO4)2 __________________
_________________
11. AgBr _________________
12. Fe2O3
__________________________
13. SeF6
__________________________
14. FePO4
__________________________
15. SCl4
__________________________
16. (NH4)2S _________________
17. MgI2
___________________________
18. NF3
__________________________
19. P4S5
____________________________
20. ZnI2
____________________________