Naming Chemical
Compounds
Review
What is a chemical formula?
• shorthand representation of the
composition of a substance using
atomic symbols and numerical
subscripts
• can represent a molecule (covalent
bonded structure) or a formula unit
(ionic bonded structure)
Review
Significance of a chemical
formula
• formula tells number and type of
atoms in a molecule or formula unit
(one atom difference can cause
change in properties)
• Examples: Ag, NaCl, HCl, Al2(SO4)3,
CaSO4  5 H2O, etc.
Naming Ionic Compounds
Binary ionic compounds
• Metal named first
• Name of non-metal has –ide added
• If metal has more than one possible
charge use stock system (Roman
numerals) or common name
Ex: NaCl, KI, FeF2, FeF3
Naming Ionic Compounds
Compounds with polyatomic
ions
• Cation is named first (using stock or common
name)
• Anion is named second (using name of
polyatomic ion)
Al(CN)3, BaSO4, Ca(NO2)2, Fe(NO3)2, NH4Cl
(DO NOT change endings of polyatomic ions!!!)
Naming Ionic Compounds
Hydrates
• ionic compounds that absorb water into their
structures
• named like regular ionic compounds, add
numeric prefix and hydrate at the end
Prefixes:
1: mono2: di3: tri4: tetra5: penta-
6: hexa7: hepta8: octa9: nona10: deca-
MgSO4  7 H2O, CuSO4  5 H2O
Naming Molecular
Compounds
Binary molecular compounds
• Element from left-most part of table is named first
• Name of second element has –ide added
• Use Greek prefixes to indicate number of atoms
Prefixes:
1: *mono(*only with second element)
2: di3: tri4: tetra5: penta-
6: hexa7: hepta8: octa9: nona10: deca-
CO, CCl4, N2O, N2O3
Naming Molecular
Compounds
Acids
• when in water, produce H+ ions, name usually
from characteristic anion
• Hydro acids: hydro + name of halogen + -ic +
acid
HCl, HF, HBr
• Oxoacids: polyatomic ion + acid (use –ous and
–ic as needed, -ic goes with > # O atoms)
H2SO4, HNO2, HNO3