CHEMISTRY
Naming Compounds
I. Binary Compounds (Only two elements)
A. Ionic compounds- Start with a _________________. 2nd element will be a
_____________________. These compounds are formed when electrons are
________________. The elements become ________, which are __________ particles.
√ Rules:
1. Name the first element (cation) using its elemental name.
Example: Na2S “Sodium” – its name from the periodic chart
2. Name the second element (anion) and drop its ending.
Example: Na2S “Sulfur” drop ending  “Sulf”
3. Add the ending “ide” to the root. The second element is always the anion.
Example: Na2S “Sodium Sulfide” The number of atoms isn’t taken into
account in the name.
Properly name the compounds below:
1. CaCl2 __________________
4. Al2O3 _______________________
2. AlF3___________________
5. Li2S ________________________
3. K3N___________________
6. Mg3N2 ___________________________________
B. Binary Covalent Compounds start with a _________________. 2nd element will be
a _________________. These compounds are formed when electrons are _________.
√ Rules:
1. Covalent compounds follow the same rules as ionic compounds (1st element
gets elemental name, 2nd element drops ending & adds –ide) BUT, it uses
prefixes (Ionic DO NOT) to indicate the number of atoms.
2. Prefixes = Number of atoms
Mono – one
tri- three
penta- five
di- two
tetra- four
hexa- six
st
3. However, if only one atom of the 1 element, don’t use a prefix. The 1st
element is never mono. Other than that, a prefix is used.
4. The 2nd element ALWAYS uses a prefix.
Example: CO2 1st element- carbon, no mono See rule B-3
2nd element- dioxide, because there are 2 oxygen atoms
Properly name the compounds below:
1. CO ___________________
4. B2O3 _______________________
2. NF3___________________
5. N2S ________________________
3. N3F__________________
6. SBr4 ________________________
C. Transition Metals- Can have more than one possible charge, therefore, a
Roman Numeral is used to indicate the Charge of the cation.
√ Rules:
1. Roman number = charge of one ion and you must figure it out using the
anion, whose charge you do know using the periodic chart.
2. All compounds are neutral. The overall charge of the compound is zero.
The compound is already balanced, just figure out what the positive charge
must be for one cation.
Example:
CuO
Copper (II) Oxide The charge of Oxygen is 2-. The
charge of the copper ion MUST be 2+ because the compound MUST equal
zero. The roman numeral is indicating that.
3. If you have more than one cation in the compound, the charge must be for
one ion only.
Example: Fe2O3
You can figure the charge of one copper ion several ways
a. When you don’t have a 1:1 ratio (like #2) you can do a switch-a-roo
The 2 from the Fe goes on the O to indicate its
charge. If this is true, then the 3 from the O
2
3
goes to the Fe to indicate its charge.
Fe O
Fe2 O 3
Fe2O3 = Iron (III) oxide
Example: Cu2 O
Cu
uu
u
O--
Cu
There are 2 copper ions and one oxygen.
What must the charge of each Cu ion be to
cancel the 2- charge of the oxygen, since the
compound is neutral? Each copper must be 1+.
Cu2O = Copper (I) oxide
Properly name the compounds below:
1. CuCl2 __________________
2. CoF3___________________
3. FeN___________________
4. Fe2O3 _______________________
5. Ni2S ________________________
6. Cr3N2 ___________________________________
Practice - Name the following:
1.
2.
3.
4.
5.
6.
7.
8.
BCl3
AlCl3
NO
CuO
N2O
KBr
Fe2S3
N2O3
9.
10.
11.
12.
13.
14.
15.
SF4
BeCl2
NaI
NO3
Ni3N
NiF3
H2O