Chemical Bonding

Ionic Compounds

Ionic Compound:

1. ionic compounds form crystals

2. high melting and boiling points

3. hard and brittle

4. conduct electricity when dissolved in water or melted

Properties

•Composed of a metal (cation) and nonmetal (anion)•Ionic bond – oppositely charged ions attract•Electrically neutral (+) = (-)

Steps to Ionic Bonding

• Copy the problem

• Draw the Lewis Structure for ea. element used in bonding

• CATION = RED

• ANION = BLUE/GREENISH

• Show donated e- with an arrow

• Show New ions charges

• Put a BOX around the Formula

Ionic Bonding

Na Cl

1. Sodium and Chlorine

●● ●

●

●

●

●

●

donates e-

Na+ ●

Cl●

●●

●

●

●

●

2. Potassium and Oxygen

K O● ●

●

●

●●

donates e -

K+● O

●●●

●●

●

●

●

+

+

K●

donates e-

K+

-2

+1 -2

-

K2O

NaCl

+1 -1

Does O have 8?

Al

3. Aluminum and Bromine

Mg N●

●●

●●

Mg+2● N

●●●

●●

●

●●

+● Mg+2

-3

● ●●

●●

●●

●

Al+3

● Br●

●●

●

●

●

●

+

●

●

Br● ●

●

●●

●●Br

● ●●

●●

●●Br

+3 -1

● Br●

●●

●

●

●

●

● Br●

●●

●

●

●

●

-

-

-+2 -3

Mg

4. Magnesium and Nitrogen

Mg●

●

●

●

N●

●

●●

●

Mg+2● N

●●●

●●

●

● -3

AlBr3

Mg3N2

Does Al have moreelectrons?

Does N have 8 yet?

What about Mg’s other e-?

Does N have 8 yet?

CharacteristicCovalent compoundCovalent compoundMolecular compoundMolecular compound Ionic compoundIonic compound

Representative unitMolecule

(atoms sharing electrons)

Formula unit (balance of

oppositely charged ions)

Type of elements NonmetallicMetallic combined

with nonmetallic

Melting & Boiling point

Low High

Important differences between covalent Important differences between covalent and ionic compoundsand ionic compounds

Bonding in Metals

Metallic bonds – the attraction between positive ions and surrounding mobile electrons Sea of Electrons

Metal cations

• Good conductors of electrical current, ductile (wires), malleable (forced into shapes)