Naming ionic
compounds
Review: Ionic compounds
Ionic compounds consist of at least one metal and one
non-metal
 Metals give up electrons to non-metals which accept
electrons
 Cations are ions that are positively charged; usually
metals



Anions are ions that are negatively charged; usually nonmetals
Ionic bonds are formed between elements of ionic
compounds.
Binary compounds

Compounds that are made up of two elements are
called binary compounds.

Sodium chloride (NaCl) is an example of a binary
compound

Magnesium chloride (MgCl₂) is an example of a binary
compound

NaOH is not a binary compound because it contains
more than two elements.
Naming binary ionic compounds
Two rules for naming binary ionic compounds:
1.
The first element in the name and formula is the metal
2.
The second element, the non-metal, is named as an ion. In other
words, the suffix “-ide” is attached to the name.
Example: the compound formed from lithium and
fluorine is named lithium fluoride
Examples

The compound formed from sodium and chlorine is
named sodium

chloride
The compound formed from magnesium and nitrogen is
named magnesium
nitride
You try…
The compound formed from magnesium and oxygen is named…?
magnesium oxide
The compound formed from lithium and bromine is named…?
lithium bromide
The compound formed from beryllium and phosphorus is named…?
beryllium phosphide
Review: formulas for binary ionic
compounds

The chemical formula shows the simplest whole number
ratio of each type of ion in the compound.

Example: the formula CaF₂ indicates that any crystal of
calcium fluoride contains two fluoride ions for every one
calcium ion (2:1 ratio of fluorine to calcium)
Review: formulas for binary ionic
compounds

To determine the formula for any binary ionic
compounds, use the periodic table to determine the
number of transferred electrons between the two
elements.

For groups 1, 2, and 13-18 you can use the group
number to determine the common charge
Transition metals
Groups 3-12
 Transition metals often
form more than one
cation.
 For example, Nickel
forms both Ni 2+ and
Ni3+ cations.
Naming Transition Metal Cations Using the
Stock System

For metals with more than one cation, we distinguish
between cations by writing the cation charge in Roman
numerals and in parenthesis after the name of the metal

The first 10 Roman numerals are: I, II, III, IV, V, VI, VII, VIII, IX
X)
Example: Cu + is called copper (I) and Cu 2+ is called
copper (II)
Example: The ionic compound that forms from Cu 2+ and
oxygen is named copper (II) oxide
You try…

Example: the compound that forms from Fe3+ and O2- is
named…
iron (III) oxide

Example: the compound that forms from Fe2+ and S2- is
named…
iron (II) sulfide

Example: the compound that forms from Fe3+ and N3- is
named…
iron (III) nitride
Determining cation charges from chemical
formulas
Example: Which iron cation, Fe 2+ or Fe 3+ is in FeCl₂?
Solution

Write the two ions involved: Fe? + and Cl-

The total negative charge is 2- because there are two
chloride anions

There is only one iron anion, so it has to be 2+ in order to
balance the 2-

The iron cation is Fe 2+
You try…
Example: What is the cation’s charge in TiCl₄?

Cl is 1- and there are 4 of them, so a total anion charge of 4-

There is only one atom of titanium so it has to be Ti 4+
Example: What is the cation’s charge in FeBr₃?

Bromine ions have a 1- charge

There are 3 atoms of Bromine so a total anion charge of 3-

There is only 1 atom of iron so it has to be Fe 3+
Writing chemical formulas from compound
names
Example: write the chemical formula for copper (II) oxide
Solution

The copper cation is Cu2+ because of the Roman
numeral (II)

The periodic table says the oxide anion is 2-

The compound must be neutral so there must be one
ion of each element

The formula is CuO. Total charges add up to zero.
You try…
Example: Write the chemical formula for cobalt (II) chloride

Cobalt (Co) is 2+ as indicated by the Roman numeral (II)

Chlorine (Cl) has a 1- charge according to the periodic
table

Two ions of chlorine are needed to balance the 2+
charge from cobalt

The chemical formula is CoCl₂
You try…
Example: Write the chemical formula for chromium (III)
oxide

Chromium (Cr) has a 3+ charge as indicated by the
Roman numeral (III)

Oxygen has a 2- charge as indicated by the periodic
table

To balance the charges, 2 ions of chromium are needed
for 3 ions of oxygen

The chemical formula is Cr₂O₃