(2.2) IONIC COMPOUNDS
(p128-129)
NAMES & FORMULAS
Compounds
Recall: There are two main types of
compounds:
 IONIC and MOLECULAR
NaCl, K2SO4
H2O, C6H12O6
Ionic Compounds


Ionic compounds are formed by combining
a metal and a non-metal.
The positive ion (from the metal) and
negative ion (from the non-metal) bond to
each other.
Ion Symbols and Names



The symbol for an ion is the element
symbol with a superscript showing the
ionic charge
Metals: The name does not change
from the element name unless the
element is multivalent (can form
different ions).
Na1+ Ca2+ Cu1+
Cu2+
sodium
calcium
copper I
copper II
Ion Symbols and Names

Non-Metals: The name changes its
ending to “ide”

Cl1-
O2-
S2-
chloride
oxide
sulfide
Naming Ionic Compounds

An ionic compound has a two-part
name:
first
second
Metal ion
Non-metal ion
Positive ion
Negative ion
Keeps its name Changes ending to “ide”
Naming Ionic CompoundsPractice
a) sodium & chlorine
b) potassium & oxygen
Formulas for Ionic Compounds


What is the chemical formula for the
ionic compound formed by magnesium
and oxygen?
STEP ONE:

Write the symbol for each element.
Formulas for Ionic Compounds

STEP TWO:

add the ionic charges of each
Formulas for Ionic Compounds

STEP THREE:

Criss-cross the charges
Formulas for Ionic Compounds

STEP FOUR:


Write the formula using subscripts.
STEP FIVE:

Simplify or reduce the ratio, if possible
Formulas for Ionic Compounds
Try these:
aluminium and oxygen
potassium and nitrogen
copper I and sulfur
Answers:



Al2O3
K3N
Cu2S
“Weirdos”



Multivalent elements can form ions
more than one way
There has to be a method of identifying
which valence (charge) is used
Pb, Fe, Cu, Sn, Co
to name a few.
Multivalent elements
Pb2+ 4+ on the periodic table means
lead II (Pb2+) or lead IV (Pb4+)




Fe2+ 3+  iron II or iron III
Cu1+ 2+  copper I or copper II
Sn2+ 4+  tin II or tin IV
WEIRDOS
 CuCl 
 CuCl2 

Fe2O3 
HOMEWORK

Worksheet 2.2 (A)
compound naming
- both sides!