IONIC & COVALENT BONDING

THE OCTET RULE

Octet Rule

• Atoms bond in order to achieve an electron configuration that is the same as the electron configuration of a noble gas

• Ie. They have 8 electrons in their filled outer energy level (except He)

Chemical Bond

• The force of attraction between two atoms or ions.

IONIC BONDING

• Some elements tend to gain electron(s) readily while others tend to lose electron(s) (low I.E.)

• When an active element (metal) reacts with an active non-metal), electrons are transferred from the metal to the non-metal. Atoms of the non-metal become anions while the metals become cations. These ions are attracted to each other by electrostatic forces.

Electrostatic Forces

• Attraction between oppositely charged particles.

Ionic Bond

• The type of chemical bond resulting from the electrostatic force of attraction between oppositely charged ions (as formed when metallic atoms transfer electrons to non-metallic atoms).

Example: electron dot formula to show the formation of the ionic compound NaCl sodium chloride table salt

Formation of Cation

11p+

sodium atomNa

e-

loss of one valence

electron

e-

e-

e-

e-e-

e-

e-

e- e-

e-

sodium ionNa+

11p+e-

e-

e-

e-e-

e-

e-

e-

e-

e-e-

Formation of Anion

17p+

chlorine atomCl

e-

e-

e-

e-

e-e-

e-

e-

e- e-

e-

e-

e-

e-

e-

e-

e-

e-

gain of one valence

electron

chloride ionCl1-

e-

17p+e-

e-

e-

e-e-

e-

e-

e-

e-

e-

e-

e-

e-

e-

e-

e-

e-

Formation of Ionic Bond

chloride ionCl1-

17p+e-

e-

e-

e-e-

e-

e-

e-

e-

e-

e-

e-

e-

e-

e-

e-

sodium ionNa+

11p+e-

e-

e-

e-e-

e-

e-

e-

e-

e-

e-

e-

Mg2+

IONIC BONDING: Formation of Magnesium Chloride

Mg Mg2+

Cl

Cl

Cl

Cl

Loses 2e- Each gains 1e- One magnesium ion Two chloride ions Mg2+ Cl1-

[(2+) 2 (1-) = 0]

MgCl2 magnesium chloride

Ionic Bonding

Na Cl

Ionic Bonding

Na+ Cl-

Ionic Bonding• All the electrons must be accounted for

Ca P

Ionic Bonding

Ca P

Ionic Bonding

Ca2+ P

Ionic Bonding

Ca2+ P

Ca

Ionic Bonding

Ca2+ P 3-

Ca

Ionic Bonding

Ca2+ P 3-

Ca P

Ionic Bonding

Ca2+ P 3-

Ca2+ P

Ionic Bonding

Ca2+ P 3-

Ca2+ P

Ca

Ionic Bonding

Ca2+ P 3-

Ca2+ P

Ca

Ionic Bonding

Ca2+ P 3-

Ca2+P 3-

Ca2+

Ionic Bonding

= Ca3P2 Formula Unit

Calcium Phosphide

Ionic Compound

• A pure substance composed of positively charged ions and negatively charged ions in a fixed ratio

Classwork problems (a)

Show the bonding between the following1. Magnesium and Oxygen2. Potassium and Chlorine3. Calcium and Fluorine4. Lithium and Nitrogen5. Aluminum and Fluorine

Homework problems

These are slightly harder6. Magnesium and Phosphorus7. Beryllium and Nitrogen8. Calcium and Sulphur9. Magnesium and Nitrogen10. Aluminum and Oxygen

Ionic Bonding

Crystalline structure

• i.e. Crystal lattice structure the rigid arrangement of ions

Solution animation

What happens when only non-metal elements are involved? . . . . . . . .

COVALENT BONDING