Chemical Bonding
Ionic Bonding
• Ions are atoms that have lost or gained one or more
electrons, resulting in a positive or negative charge
• Cation = a positively charged ion
• Anion = a negatively charged ion
• Elements in the vertical column families develop the
same ionic charges:
• Metals tend to lose electrons (form cations).
• Non-metals tend to gain electrons (form anions).
• Metal cation + Non-metal anion = ionic compound.
• Are the following ions, cations or anions?
• Chlorine ion
• Magnesium ion
• Oxygen ion
Naming Binary Ionic Compounds
• A binary ionic compound is a compound composed of
a metal cation and a non-metal anion.
• The first part of the name identifies the positive ion,
which is the metal cation.
• The second part of the name identifies the negative
ion, which is the non-metal anion.
• The name of the non-metal ion always ends with the
sufix –ide.
Elements in Ionic
Compound
Name of Ionic Compound
magnesium and
phosphorus
magnesium phosphide
sodium and chlorine
sodium chloride
calcium and bromine
calcium bromide
aluminum and oxygen
aluminum oxide
Writing the chemical formulas for
binary ionic compounds
•
•
•
•
•
1.
2.
3.
4.
5.
Write the symbols with the metal first:
Write the charge above each symbol.
Cross over the numbers, not the charges.
Never write a subscript 1.
Write the formula, reduce if possible.
aluminum oxide
• Practice:
Elements in Ionic
Compound
Ions
Name
Chemical
Formula
potassium and bromine
K+1 and Br-1
potassium bromide
KBr
magnesium and chlorine
Mg+2 and Cl-1
magnesium chloride
MgCl2
aluminum and sulphur
Al+3 and S-2
aluminum sulphide
Al2S3
calcium and oxygen
Ca+2 and O-2
calcium oxide
CaO
magnesium and bromine
Mg+2 and Br-1
magnesium bromide
MgBr2
calcium and iodine
Ca+2 and I-1
calcium iodide
CaI2
aluminum and oxygen
Al+2 and O-2
aluminum oxide
Al2O3
potassium and chlorine
K+1 and Cl-1
potassium chloride
KCl
magnesium and nitrogen
Mg+2 and N-3
magnesium nitride
Mg3N2
sodium and phosphorus
Na+1 and P-3
sodium phosphide
Na3P
Multivalent Metals
• Multivalent metals have more than one ion charge
listed on the periodic table.
• For example, copper can form ions with a +1 or +2
charge.
• Cu+1 = copper (I)
• Cu+2 = copper (II)
• Cu3N = Cu+1N-3 = copper (I) nitride
• Practice:
Chemical Formula
Name
SnS2
tin (IV) sulphide
Fe2O3
iron (III) oxide
FeF3
iron (III) fluoride
Cr3P2
chromium (II) phosphide
Multivalent Metals Practice:
Chemical Formula
Name
SnS2
FeO
copper(II) oxide
Cu3N
Cu2O
mercury(II) chloride
Answers
SnS2
tin(IV) sulphide
FeO
iron(II) oxide
CuO
copper(II) oxide
Cu3N
copper(I) nitride
Cu2O
copper(I) oxide
HgCl2
mercury(II) chloride
Molecular Compounds
• Molecular compounds are formed when atoms of two
or more different elements SHARE electrons
• A covalent bond is formed when electrons are shared
between atoms.
• For example, water (H20)
Diatomic molecules
• Elements that have two atoms joined by one or more
covalent bonds to form a molecule
• H2, O2, Br2, F2, I2, N2, Cl2
oxygen molecule
Characteristics of Molecular
Compounds
What is the difference between a molecular
formula and structural formula?
• A molecular formula is a chemical formula – it shows
the number of atoms of each element.
• A structural formula shows the arrangement of the
atoms that make up a molecule.
water = H2O
glucose = C6H12O6
Binary molecular compounds
• Binary molecular compounds are compounds composed
of two non-metals joined by one or more covalent bonds.
• For example: carbon dioxide (CO2)
Steps to naming a binary molecular compound:
Prefix
Number
1. How many atoms of the 1st element? Write the
correct prefix. Never use the prefix mono- for
the 1st element.
mono-
1
di-
2
tri-
3
2. How many atoms of the 2nd element? Write the tetracorrect prefix.
penta3. Write the suffix –ide to the 2nd element.
hexa-
4
hepta-
7
octa-
8
For example: N2O4 = dinitrogen tetraoxide
5
6
Practice:
Chemical Formula
Name
NO2
bromine monochloride
PCl3
disulphur dinitride
CCl4
diphosphorus hexoxide
CO
Answers:
Chemical Formula
Name
NO2
nitrogen dioxide
BrCl
bromine monochloride
PCl3
phosphorus trichloride
S2N2
disulphur dinitride
CCl4
carbon tetrachloride
P2O6
diphosphorus hexoxide
CO
carbon monoxide
Ionic Compounds with Polyatomic Ions
• A polyatomic ion is an ion that is composed of more
than one atom.
• A ternary compound is a compound composed of
three different elements.
• For example: calcium hydroxide Ca(OH)2, each
molecule is composed of 1 calcium atom, 2 oxygen
atoms, and 2 hydrogen atoms.
• Naming compounds with polyatomic ions follows the
same rules as other ionic compounds:
1. Write the cation 1st (e.g. calcium, Ca+2)
2. Write the anion 2nd (e.g. hydroxide, OH-)
Common Polyatomic Ions
Charge Name
+1
-1
-2
-3
Chemical Formula
ammonium
(NH4 ) +
hydrogen carbonate (bicarbonate)
(HCO3 ) -
hydroxide
(OH ) -
nitrate
(NO3 ) -
nitrite
(NO2 ) -
chlorate
(ClO3 ) -
carbonate
(CO3 ) –2
sulphate
(SO4 ) –2
sulphite
(SO3 ) –2
peroxide
(O2 ) –2
phosphate
(PO4 ) –3
phosphite
(PO3 ) -3
Practice:
Name
Chemical Formula
calcium carbonate
CaCO3
ammonium sulphate
(NH4)2SO4
Mg3(PO3)2
potassium sulphate
calcium nitrate
Fe2(SO3)3
sodium phosphate
LiOH
cobalt(II) phosphate
Answers:
Name
Chemical Formula
calcium carbonate
CaCO3
ammonium sulphate
(NH4)2SO4
magnesium phosphite Mg3(PO3)2
potassium sulphate
K2SO4
calcium nitrate
Ca(NO3)2
iron(III) sulphite
Fe2(SO3)3
sodium phosphate
Na3PO4
lithium hydroxide
LiOH
cobalt(II) phosphate
Co3(PO4)2
So what are all of these compounds?
• sodium chloride
• zinc oxide
• calcium carbonate
• calcium hydroxide
So what are all of these compounds?
• nitrogen dioxide
• dinitrogen tetraoxide
• phosphorus trichloride
• sodium nitrite
Naming Acids
• Binary acids are composed of hydrogen and a
non-metal
• To name a binary acid:
– 1. Wire the root of the non-metal name.
– 2. Add the prefix hydro- to the root name.
– 3. Add the ending –ic acid to the root name.

For example:
HF(aq) = hydrofluoric acid
 HCl(aq) = hydrochloric acid
 HI(aq) = hydroiodic acid

• Oxoacids are composed of hydrogen, oxygen, and
another element.
• To name an oxoacid:
– 1. Write the name of the anion, without the –ate or –ite
ending.
– 2. If the anion name ended in –ate, replace it with –ic at
the end of the name.
– 3. If the anion name ended in –ite, replace it with –ous
at the end of the name.
– 4. Add the word acid.
 For example:
H2SO4(aq) = sulphuric acid
 H2SO3(aq) = sulphurous acid
 H3PO4 (aq) = phosphoric acid
 H2CO3 (aq) = carbonic acid

Naming Bases
• Many bases are ionic compounds
composed of metal ions and hydroxide
ions. They are named the same way as
other ionic compounds.
• For example:
– NaOH = sodium hydroxide
– Ca(OH)2(aq) = calcium hydroxide