Chapter 15
Ionic Bonding
Valence Electrons
Do the electron configuration for the following
elements
• Li
• Be
• B
• O
• F
• Ne
Valence Electrons
• Now look at the outermost electrons by
looking at the last s and p orbital
• Circle and count these electrons
• These are the valence electrons
Valence electrons
– Valence electrons are in the highest energy level
of an element’s atom
– Valence electrons are the same as group # (roman
numeral) for the group A representative elements
– Valence electrons are usually the only electrons
used in chemical bonds
– We use valence e- to write Lewis Dot Structures
Valence electrons (cont.)
A. Lewis Dot Structure
Ex: bromine
● ●
●
Br
● ●
●
●
Electron configurations for cations & anions
A. Octet Rule: when forming compounds atoms
want to have 8 electrons (s2p6) like the noble
gases (except He)
Cations (metals) tend to lose electrons, positively
charged ion
lose 1 e+
2
2
6
1
2 2
6
Na 1s 2s 2p 3s
Na
1s 2s 2p
(atom)
(cation)
octet
Using the Dot Structure
●
lose 1 e-
Na
(cation)
(neutral
atom)
●
Mg
(neutral
atom)
Na
+
lose 2
●
e-
Mg
(cation)
2+
Anions (Nonmetals) have negative charges because
they gain electrons
Cl
gain 1 e-
1s22s22p63s23p5
(atom)
Cl
1s22s22p63s23p6
(chloride ion)
valence
octet
Using the Dot Structure
●●
●
Cl
●●
●
gain 1
● ●
e-
●
●
●
●
O
●
●
●
(neutral
atom)
-
●●
(chloride ion)
(neutral
atom)
● ●
Cl
●
●
gain 2e-
●
●
● ●
O
●
●
●●
(oxide ion)
2-
Practice
●●
●
N
●
gain 3e-
●
●
●●
N
●
●
3-
● ●
●
(nitride ion)
●
Lose 1 e-
Li
● ●
●
I
● ●
●
●
gain 1
e-
Li
●
●
+
I -
● ●
●●
(iodide ion)
●
Ca
●
●
●
Lose 2e-
Ca
+2
Ionic Compound
•Composed of a metal (cation) and nonmetal (anion)
•Ionic bond – oppositely charged ions attract
•Electrically neutral (+) = (-)
A. Properties
1. ionic compounds form crystals
2. high melting and boiling points
3. hard and brittle
4. conduct electricity when dissolved in
water or melted
Ionic Bonds
+1
-1
1. Sodium and Chlorine
●●
donates e-
●
Na
+
●
Cl
Na+
●
●
●
●
-
● ●
Cl
●
●
● ●
● ●
NaCl
+1
-2
2. Potassium and Oxygen
●
K
●
K
● ●
+
donates e-
●
O
●
●
●
K+
● ●
●
●
K+
K2 O
O
● ●
-2
●
●
AlBr3
+3
-1
3. Aluminum and Bromine
●●
●
●
Br
● ●
●●
Al
+
●
Br
Br
●
●
●
● ●
●●
● ●
●
●
●
●
Al+3
●
●
●
●
Mg
●
●
Mg
N
●
●
+
●
● ●
●
●
-
● ●
Br
●
●
Br
●
●
-
● ●
● ●
-
● ●
● ●
●
●
●
●
●
●
●
Br
●
●
● ●
+2
-3
4. Magnesium and Nitrogen
Mg
● ●
N
●
●
Mg+2
Mg+2
Mg+2
● ●
●
●
N
● ●
● ●
●
●
N
● ●
Mg3N2
-3
●
●
-3
●
●
OUTPUT EXAMPLE:
+1
-1
1. Potassium & Fluorine
●
K
●●
+
●
F
●●
●
●
K
+
●
●
●●
F
●●
●
●
KF
-