2.3: Chemical Bonding &
Electronegativity
Bonding & Electronegativity

Electronegativity is a measure of an atom’s ability to attract
electrons in a chemical bond

ΔEN means difference in electronegativity
 This
is a number that tells us what type of bond will form
 Will
range from 0 – 3.3
ΔEN: 3.3
Ionic
1.7
0.5
Polar covalent
0
non-polar covalent
Bonding & Electronegativity
Ex: Calculate ΔEN and determine type of bonding for
a)
KF
b) O2
c) HCl
Bonding & Electronegativity
Ex: Calculate ΔEN and determine type of bonding for
a)
KF
KF: 4.0 – 0.8 = 3.2 = ionic
b) O2
c) HCl
Bonding & Electronegativity
Ex: Calculate ΔEN and determine type of bonding for
a)
KF
KF: 4.0 – 0.8 = 3.2 = ionic
b) O2
O2: 3.5 – 3.5 = 0 = non-polar covalent
c) HCl
Bonding & Electronegativity
Ex: Calculate ΔEN and determine type of bonding for
a)
KF
KF: 4.0 – 0.8 = 3.2 = ionic
b) O2
O2: 3.5 – 3.5 = 0 = non-polar covalent
c) HCl
HCl: 3.0 – 2.1 = 0.9 = polar covalent
Bonding & Electronegativity
Non-Polar Covalent Bond

Electrons are shared equally

Usually between atoms of the same element (ie: Cl2)
Bonding and Electronegativity
Polar Covalent Bond

Electrons are NOT shared equally

Usually between atoms of the DIFFERENT elements (ie: HCl)

Results in a charge separation called a DIPOLE
 The
shared electron pair spends the most time around the more electronegative
atom (in this case, Cl – the electron pair spends more time closer to the Cl than
the H)
 The
more EN atom has a partial negative charge (δ-)
 The
less EN atom has a partial positive charge (δ+)
Polarity and Shape of Molecule

Example: H2O, CO2, NH3, CH4
Read pages 70 – 73 and answer #1-8.