Chemical Bonding
Chemical Bonding
Remember Chemical Bonding is a result of
valence electrons being gained, lost, or
shared between atoms
 There are primarily three types of bonding
between atoms, ionic bonds, polar
covalent bonds, and non-polar covalent
bonds

Types of Bonding

The differences in electronegativity
reflects the character of bonding between
elements
Chemical Bonding
Most atoms have lower potential energy
when they are bonded to other atoms
than they have as they are independent
particles
 What does this mean?
 It means they “like to be bonded”

Covalent Bonds

When two atoms form a covalent bond, their
shared electrons form overlapping orbitals
Covalent Bonds
- water is a polar molecule because oxygen is more electronegative than
hydrogen, and therefore electrons are pulled closer to oxygen.
Nobel Gases

Nobel gasses are unreactive because they are
very stable

Other atoms do not have completely filled
orbitals so they “want” to fill them with help
from other atoms to become stable
Electron Dot Notation

Electron-dot notation is an electronconfiguration notation in which only the
valence electrons of an atom of a
particular element are shown indicated by
dots placed around the element symbol
Electron Dot-notation
Lewis Structures
Electron dot notation is used to represent
molecules
 The pair of dots between the two symbols
represents the shared electron pair of the
hydrogen-hydrogen and fluorine-fluorine
covalent bond H:H

Lewis Structures
The pair of dots between the two symbols
represents the shared pair of a covalent
bond
 The unshared pair, the lone pair, is not
involved in bonding and belongs just to
that one atom

Structural Formula
The pair of dots represents a shared pair
of electrons in a covalent bond is replaced
by a dash: H-H
 A structural formula indicates the kind,
number and arrangement, and bonds but
not the unshared pairs of the atoms in a
molecule:
F-F
H-Cl

Structural Formulas

A single covalent bond, or single bond, is
a covalent bond in which one pair of
electrons is shared between two atoms :
Example: diatomic hydrogen H2: H-H
A double covalent bond, or a double bond,
is a covalent bond in which two pairs of
electrons are shared between two atom
Example: diatomic nitrogen N2:

Structural Formulas

A triple covalent bond, or simply a triple
bond, is a covalent bond in which three
pairs of electrons are shared between two
atoms
– Example: ethyne C2H2:

Multiple bonds, double and triple bonds,
have greater bond energies and are
shared in bond length, they are STRONG!!
Drawing Structures
1.
Determine the type and number of
atoms in the molecules.
For example Draw the Lewis structure of
iodomethane CH3I
The formula shows 1 Carbon, 3 Hydrogens,
and 1 Iodine
Drawing Structures
2. Write the electron-dot notation for each
type of atom in the molecule. Place one
electron dot on each side of the element
before pairing any electrons.
Carbon is in group 14, 4 valence electrons
Iodine is in group 17, 7 valence electrons
Hydrogen is in group 1, 1 valence electron
Drawing Structures
3. Determine the total number of valence
electrons available in the atoms to be
combined.
C
1 x 4e = 4e
I
1 x 7e = 7e
3H 3 x 1e = 3e
14e
Drawing Structures
4. If carbon is present, it is the central
atom, otherwise, the least
electronegative atom is in the center.
Hydrogen is never central
Drawing Structures
5. Add unshared pairs of electrons to each
nonmetal atom (except hydrogen) such that
each is surrounded by eight electrons.

Distribute the electron dots so that each
atom, except for hydrogen, beryllium, and
boron, satisfies the octet rule. Change each
pair of dots that represents a shared pair to
one dash, two, or three dashes
Drawing Structures
6. Count the number of electrons
surrounding each atom and check the
number of valence electrons is the same
number you started with in step 3.