Chapter 9
Chemical Names and Formulas
Anything in black letters = write it in
your notes (‘knowts’)
What is the difference between a chemical
name and a chemical formula?
Chemical Names
Chemical Formulas
sodium chloride
NaCl
glucose
C6H12O11
carbon dioxide
CO2
9.1 – Naming Ions
Monatomic Ions – a single atom with a charge
Monatomic anions end in ide
F- = fluoride,
Cl- = chloride,
Br- = bromide,
etc…
Oxidation Number – the charge of an ion
Get out your yellow periodic tables…
Oxidation Number
Copper can be
Cu+1 or Cu+2
Roman numerals are used to show the
oxidation number of a variable cation.
Copper (I) = Cu+
Copper (II) = Cu2+
Iron (II) = Fe2+
Iron (III) = Fe3+
Classical names can also be used.
Copper (I) – Cu+ = cuprous
Copper (II) – Cu2+ = cupric
Iron (II) – Fe2+ = ferrous
Iron (III) – Fe3+ = ferric
Polyatomic Ions – more than one atom with a charge
(table on p. 268 or on yellow p. table)
Polyatomic Ions to Memorize!
Charge
Formula
Name
1–
CH3COO–
NO3–
OH–
Acetate or ethanoate
Nitrate
Hydroxide
2–
SO42–
CO32–
Sulfate
Carbonate
3–
PO43–
Phosphate
1+
NH4+
Ammonium
9.2 – Naming and Writing Formulas for Ionic Compounds
Binary Compound – composed of only 2 elements;
can be ionic or covalent.
Circle the binary compounds,
NaCl
CaO
FeSO4
AlF3
ZnS
ZnSO4
K3PO4
H 2O
subscripts
Binary compounds will end in ide.
IONIC COMPOUNDS
Writing Formulas from the Name
Write symbols and charges for each ion in the compound;
cation first,
Balance the charges using subscripts (crisscross method)
Naming Compounds from the Formula
Name cation first and then anion.
Use polyatomic ions if formula has more than 2 elements.
use a roman numeral if metal cation can have more than one
charge,
end in ide if binary.
Covalent compounds have slightly different rules…
CrissCross Method
write the formula for iron(III) oxide
+3
Fe
-2
O
Fe2O3
Write the formula for iron(II) oxide
+2
Fe
-2
O
Fe2O2
FeO
Write formulas for these compounds,
calcium chloride
potassium sulfate
barium nitrate
calcium fluoride
copper(II) oxide
ammonium phosphate
Name these compounds,
MgCl2
AlF3
CaO
FeSO4
ZnS
K3PO4
NaOH
ASSIGNMENT:
Read 9.1 & 9.2
9.1 & 9.2 Practice Worksheet
9.3 – Naming and Writing Formulas for Molecular Compounds
Identify Compounds as Ionic or Covalent
Naming Binary Molecular Compounds (prefixes)
Writing Formulas for Molecular Compounds
So far, we have only discussed naming ionic compounds.
Now we will discuss how to name covalent compounds.
ionic compounds
covalent compounds
FeCl3
iron(III) chloride
CO2
carbon dioxide
NaCl
sodium chloride
PF3
phosphorus trifluoride
K3PO4
potassium phosphate
CS2
carbon disulfide
Binary molecular compounds use prefixes to show the
number of atoms.
Prefixes Used in Naming Binary
Molecular Compounds
Prefix
Number
mono-
1
di-
2
tri-
3
tetra-
4
penta-
5
hexa-
6
hepta-
7
octa-
8
nona-
9
deca-
10
Don’t use mono for the first element in a chemical formula
CO
CO2
carbon monoxide
carbon dioxide
not monocarbon monoxide
not monocarbon dioxide
Binary compounds always end in ide
Name these compounds,
NCl3 nitrogen trichloride
BCl3
boron trichloride
N2H4 dinitrogen tetrahydride
NO2
nitrogen dioxide
N2O
dinitrogen oxide
SO3
sulfur trioxide
CO2
carbon dioxide
Write formulas for these compounds,
phosphorus pentachloride PCl5
iodine heptafluoride
IF7
chlorine trifluoride
ClF3
carbon monoxide
CO
carbon disulfide
CS2
sulfur trioxide
SO3
ASSIGNMENT:
Chapter 9 #27-36 (page 283)