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Chemistry 111/112
The Nature of Covalent Bonding
The Octet Rule in Covalent
Bonding
 In
the case of covalent bonding, electrons
are shared between atoms in order to
achieve a noble gas configuration
 One
shared pair of electrons between
atoms is a single covalent bond

Ex. H2, Cl2, H2O
Structural Formulas
 The
two dots that represent the shared
pair can be substituted with a dash
A
structural formula represents the
covalent bonds by dashes and shows the
arrangement of covalently bonded atoms
 Any
pairs of e- that are not involved in
sharing are called lone pairs
Double and Triple Covalent Bonds
 Atoms
may form double or triple bonds if
there is an abundance of single e Two shared pairs = double covalent bond
 Three shared pairs = triple covalent bond
 Some
molecules contain double bonds
(O2) and some contain triple bonds (N2).
Structural Formulas
 Take
a look at carbon dioxide…
When lone pairs come in handy…
 Sometimes,
a lone pair has to be used in
the place of a shared pair in order to
create a stable octet
 These
are called coordinate covalent
bonds
 Ex.
CO
Polyatomic Ions
 Sometimes,
two or more atoms come
together and form covalent bonds between
each other. They have an overall charge
 In
the case of ammonium, covalent bonds
are used as well as coordinate covalent
bonds.
 Ex.
Page 223
For the remainder of class…
 Guided
reading for section 8.2
 Question
21 – page 229