Ionic Bonding

Metal and Nonmetal

Electron transfer between atoms, ELECTRON
STEALING

ION formation (cation, anion)



Opposite charges attract and hold atoms together
Ions attracted to neighbords, not just one ion
Ionic Bonds—

Attractive electrostatic forces connecting cations and
anions
Ionic Bonding--Crystals

Interactions among ions lead to a patterned arrangement of
cations and anions that repeats, CRYSTAL

What is a diamond really? (diamond lattice)
Ionic Bonds

Between atoms of metals and nonmetals with very different
electronegativity



Huge difference in electronegativity
Electronegativity value > 1.7
Form between elements located on opposite sides of the
periodic table
Ionic Bonds (cont.)


Conductors
High melting point.

Water soluble

Crystallize (form crystals)

Examples; NaCl, CaCl2, K2O
Ionic Bonds: One Big Greedy Thief
Dog!
Example 1: NaCl
Example 2: CaO
Example 3: K2O You Try !
Covalent Bonding

ELECTRON SHARING between 2 atoms (nonmetals)

Formation of MOLECULES

Small difference in electronegativity

Bonding pairs—


Electron pairs shared between atoms
Nonbonding/lone pairs—


Unshared electrons, “lone wolves”
Only reside around one atom
Covalent Bonding
continued….

Between nonmetallic elements of similar electronegativity.


Small electronegativity difference <1.7
Formed between elements on the same side of the periodic
table.
Example 1: Cl2
Example 2: H2O
Multiple Bonds

Single bonds—


Double bonds—


1 electron pair shared between atoms
2 electron pairs shared between atoms
Triple bonds—

3 electron pairs shared between atoms
Example 1: CO2
Example 2: N2
What is polarity?

Focus on covalent bonds

Contributes to the properties of chemical compounds

Based on electronegativity difference between atoms within
chemical bonds
Electronegativity and Bond
Polarity

Covalent Bond
(0—0.5)
Polar Covalent
(0.5—1.9)
Ionic Bond
(1.9—3.5)
Chose your polarity
1)
Nonpolar Covalent



2)
small to same electronegativity difference
Occurs among same or similar atoms bonded together
EQUAL sharing of electrons, equal distribution of
electron density
Polar Covalent



difference in electronegativity
Most electronegative atom pulls electrons towards it
UNEQUAL sharing of electrons, electron density
displaced toward electronegative atom
Polar Covalent Bonds
Example 1:
 Arrange
the following bonds
in order of DECREASING
polarity.


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Br—Cl
Cl—Cl
Cl--F
H--Cl
I--Cl
Partial Charges

Exist in polar covalent molecules

Demonstrates tendency of one end to be “slightly”
negative or positive

NO charge on the whole molecule
Example 1: H2O
Example 2: PH3
Homework

Chemical Bonding I Worksheet