Kozinski 18/19  AP Chemistry
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Period ___ Date __/__/__
Unit 5 – Bonding and IMFs
Notes 5.2 – Basics of Bonding
Ionic Bonds: Transfer of electrons
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If the electronegativity difference is significant
between two elements, the most electronegative
element will pull the electron away from the
least electronegative element creating two ions.
These two ions will electrostatically attract each
other forming an ionic bond.
The strength of this bond depends on the lattice
energy.
Lattice Energy - Energy required to completely
separate one mole of a solid ionic compound into its gaseous ions.
NaCl(s )  Na  (g )  Cl (g )
Hlattice  788kJ / mol
Lattice energy depends on two things:
Practice
For each of the following pairs of ionic compounds, box the compound that has the highest lattice energy.
a. LiF, LiCl
b. MgF2 , MgO
c. NaCl, Na2O
d. MgO, BaS
e. Fe(OH)2, Fe(OH)3
d. NaCl, KCl
Covalent bonds: Sharing of electrons
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If the electronegativity difference is not significant enough to transfer electrons, the two atoms will share electrons
by overlapping their orbitals. They do this through hybridization (elaborated on later).
There are several electrostatic interactions in these
bonds:
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•
Attractions between electrons and nuclei,
repulsions between electrons, repulsions
between nuclei
For a bond to form, the attractions must be greater than
the repulsions.
There are two types of covalent bonds we must familiarize
ourselves with: polar covalent and non-polar covalent
bonds. The difference between the two has everything to do
with the two elements’ electronegativity. In a nonpolar
covalent bond, the electrons are shared equally.
Intro to hybridization
1. Consider this diagram:
The equilibrium bond distance is ______ nm.
The bond energy is ______ Joules which is the amount of energy you need
to add to break the bond (i.e. separate the two atoms).
2. Consider this diagram again
If two O atoms approach, their bond distance is 0.100 nm and bond
energy is 498 J. Sketch the energy curve for O2.
Elements use their valence electrons to make bonds. When they do
this, they utilize ALL of their valence shell, meaning, the s and the p
orbitals.
When these orbitals overlap and share electrons amongst the orbitals, you create a bond.
To get the orbitals to overlap, they must first hybridize.
Hybridization: The mixing of two or more atomic orbitals of
similar energies on the same atom to produce new orbitals of equal
energies
The number of “empty” spaces a hybrid orbital has will tell you how
many bonds the atom can make in a covalent bond!
Practice Drawing Lewis Structures
HF
Valence Electrons______
SiF4
Valence Electrons______
C2H6
Valence Electrons______
HCN
Valence Electrons______
NH3
Valence Electrons______
F2
Valence Electrons______
C2H2
Valence Electrons______
CO
Valence Electrons______
CH4
Valence Electrons______
O2
Valence Electrons______
C 2H 4
Valence Electrons______
CO2
Valence Electrons______
NF3
Valence Electrons______
N2
Valence Electrons______
C2F4
Valence Electrons______
CNValence Electrons______