Grade 10 Academic Science ––
Chemistry
Covalent and Ionic Bonds
Science Perspectives 10 - Section 5.6
Pages 192-195
They are distinguished by the manner in
which the atoms bind to one another in
the compound. These two types are
called molecular compounds and salts
(or equivalently ionic compounds).
Recall, a molecule is the smallest
particle of a pure chemical substance that
still retains its chemical composition and
properties.
compounds are made up of molecules
whose atoms bind to one another through
covalent bonds. Covalent Bond - The
electrons are shared between atoms.
carries a positive or negative charge as a
result of having lost or gained one or
more electrons. Ionic bonds occur due
to the mutual attraction between atoms
with positive and negative charges.
together in a lattice structure by ionic
bonds. To form an ionic compound, there
needs to be at least one metal and one
non-metal. The metal element is usually
the positive charge and the non-metal
element is a negative charge. Ions can
be single atoms, as in common table salt
sodium chloride, or more complex groups
such as calcium carbonate
NaCl (Sodium chloride)
Cl−. The salts of hydrochloric acid contain
chloride ions and are also called
chlorides. An example is table salt,
which is sodium chloride with the
chemical formula NaCl. In water, it
+
−
dissolves into Na and Cl ions.
Molecular Formula for Molecular
Compounds
As we know, molecules consist of two or
more atoms bonded to one another
through covalent bonds.
The identification of these molecules is
through their molecular formulas.
molecule. For example, benzene has six
carbon and six hydrogen atoms.
Therefore, the ratio of carbon to
hydrogen atoms is 6: 6 or simplified to
1:1. The empirical formula for benzene is
CH.
Molecular Formula for Ionic
Compounds
Positively charged atoms or molecules
are called cations and negatively
charged atoms or molecules are called
anions.
As suggested, cations and anions attract
one another. Conversely, cations repel
other cations, as do anions and anions.
that cation-anion attractions form a large
array called an ionic compound or salt.
The bonds holding these ions together
are called ionic bonds. However, this
array has a very specific composition
completely dictated by the charges on the
cations and anions.
determined by the requirement that the
compounds must be electrically neutral.
That is, the overall charges of the cations
and anions must be zero.
charge. Thus, one Na cation cancels one
Cl anion resulting in the formula NaCl.
This formula is called the formula unit
since it represents only one unit of the
vast NaCl array or lattice.
An ionic compounds made up of single
atom is a monatomic ion
Cation Anion Compound Ca2+
CaCl2 Ba2+ O2K+ S2BrCr3+ O2-
ClFe3+
with one notable exception - the
ammoniun cation (NH4+). The
composition of salts with polyatomic ions
is determined by the same rule as with
monatomic ions.
3
3
4
NH4+ S2Fe3+ SO32NH4+ CO22H3O+ PO43Li+ SO42NH4+ HPO42K+
CrO42Be2+ NO3Teacher Copy – Answer Sheet
charge. Thus, one Na cation cancels one
Cl anion resulting in the formula NaCl.
This formula is called the formula unit
since it represents only one unit of the
vast NaCl array or lattice.
An ionic compounds made up of single
atom is a monatomic ion
Cation Anion Compound
CaCl2 Ba2+ O2- BaO
Fe3+ Br- FeBr3 Cr3+
Ca2+ ClK+ S2- K2S
O2- Cr2O3
with one notable exception - the
ammoniun cation (NH4+). The
composition of salts with polyatomic ions
is determined by the same rule as with
monatomic ions.
3
3
Ba3(PO4)2 NH4+
SO32- Fe2(SO3)3
(NH4)2CO2 H3O+
SO42NH4+
CrO42Be2+
4
S2- (NH4)2S Fe3+
NH4+ CO22PO43Li+
HPO42K+
NO3-
HOMEWORK
Page 195, Questions 1-8, 12, 13