Unit 5- Chemical
Bonding:
Electron Dot Diagrams
X
Review: Group #’s & Valence Electrons
18
1
2
13 14 15 16 17
TRANSITION
METALS
Octet Rule:
•Most atoms form bonds in
order to obtain 8 valence e
–Full energy level stability ~ Noble
Gases
Ne
Electron Dot Diagrams
• Diagrams that represent # of
valence electrons in a given atom
• Dots indicate valence electrons
• EX: oxygen
O
Electron Dot Diagrams
Rules:
1. Write symbol
2. Find # of valence electrons
3. Place a single dot (electrons) on each
side of the symbol before pairing
them up.
Ex: Nitrogen:
N
Electron Dot Diagrams
Examples
# of v e-
diagram
Carbon
4
Bromine
7
Br
Potassium
1
K
C
Bonding
•Why do atoms form
bonds?
–To become stable by
decreasing potential
energy
–Obtain 8 valence electrons
Bonding
Covalent Bonds:
Ionic Bonds:
•Diagrams show a •Diagrams show
sharing of
gain or loss of
electrons
electrons
•Results in (+) and •Results in single,
double, or triple
(-) ions
bonds
Ionic Bonding
NaCl
•Na lost e-  becomes positive (+)
•Cl gained e-  becomes negative (-)
Charges equal ZERO for all compounds!
Ionic Bonding
Draw the Lewis structure of Li + O
O
Li
+1
Li +
2O
+
+1
Li
Li
 Li2O
Charges equal ZERO for all compounds!
Covalent Bonding
Draw the Lewis structure of Be + Cl
Cl
Single
Bond
Be
Cl Be Cl
BeCl2
Cl
Covalent Bonding
Covalent Compounds can have:
Single Bonds: 1 pair of electrons
shared
Double Bonds: 2 pairs of electrons
shared
Triple Bonds: 3 pairs of electrons
shared
Covalent Bonding
Draw the Lewis structure of C and O
O
Double
Bond
C
O C O
CO2
O
Things to Remember…
•Single atom is written
in the center
•When writing formulas,
positive atom is written
first, negative atom is
second
•All atoms have 8
valence electrons!
F
F C F
F
Diatomic Molecules
•A molecule containing only 2 atoms
•The Seven Diatomic Elements
H
Br2 I2 N2 Cl2 H2 O2 F2
N O F
Cl
Br
I