Ionic Bonding

Valence Electrons

• Number of electrons in highest occupied energy level

• To find the number of valence electrons = look at its group number

• atoms tend to gain or lose electrons in order to achieve the electron

configuration of a noble gas

Octet Rule

Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons

C would like to N would like toO would like to

Gain 4 electronsGain 3 electronsGain 2 electrons

REMEMBER...

• Metals tend to lose their valence electrons

• Some nonmetals tend to gain electrons or to share with other nonmetallic elements to achieve a noble gas configuration

Ion Formation

• When an atom loses an electron it produces a positively charged ion (cation)

Now has full shell with similar electronic configuration to Neon

(stable noble gas configuration)

Ion Formation

• The gain of negatively charged electrons by a neutral atom produces an anion.

• When an atom gains an electron it produces a negatively charged ion (anion)

Now has full shell with similar electronic configuration to Argon

(stable noble gas configuration)

Lewis Dot Diagrams

Ionic Bonds

• Compounds composed of cations and anions are called ionic compounds.

• Although they are composed of ions, ionic compounds are electrically neutral.

• The electrostatic force that hold ions together in ionic compounds is called Ionic Bond

Practice, Practice, Practice

Use electron dot structures to

determine formulas of the ionic

compounds formed when

1. potassium reacts with iodine.

2. Aluminum reacts with oxygen.

Properties of Ionic Compounds

1. Most are crystalline solids at room temperature.

2. High melting points.

3. Conduct electricity when melted or dissolved in water.

Practice, Practice

Write the formulas for each compound:1.Barium chloride2.Lithium oxide

3.Magnesium oxide4.Calcium flouride

Learning Check

Give the ionic charge for each of the following:A. 12 p+ and 10 e-

1) 0 2) 2+3) 2-

B. 50p+ and 46 e-

1) 2+ 2) 4+3) 4-

C. 15 p+ and 18e-

2) 3+ 2) 3- 3) 5-

Learning Check

A. Number of valence electrons in aluminum1) 1 e- 2) 2 e- 3) 3 e-

B. Change in electrons for octet1) lose 3e- 2) gain 3 e- 3) gain 5 e-

C. Ionic charge of aluminum 1) 3- 2) 5- 3) 3+

Review...

• The number of valence electrons is the number of electrons in the outermost energy level of an atom

• A chemical bond is a force that holds two atoms together

• An ionic bond is an electrostatic force that holds a positively charged ion and a negatively charged ion together in an ionic compound

• Atoms are always trying to achieve stability by having a configuration of a noble gas (2 electrons in first energy level OR 8 in the outermost energy level – OCTET RULE)