Chemical Bonding

Ionic Bonding and Ionic Compounds

Ionic Bonding and Ionic CompoundsObjectives:

1. Compare and contrast a chemical formula for a molecular compound with one for an ionic compound.

2. Discuss the arrangement of ions in crystals.

3. Define lattice energy and explain its significance.

4. List and compare the distinctive properties of ionic and molecular compounds

5. Write the Lewis structure for a polyatomic ion.

Ionic Bonding and Ionic Compounds

H2O

NaCl

Ionic Compound – positive and negative ions combined is such a way to yield a neutral compound.

Formula unit – simplest ratio of atoms found in an ionic compound

Formation of Ionic Compounds

Ionic compounds form as a result of the transfer of elecrons.

Formation of Ionic Compounds

Formation of Ionic Compounds

• Cations and anions are arranged in a crystal lattice; minimizing potential energy

• Arrangement among ions represents a balance between attractive and repulsive forces

• Lattice energy – energy released when an ionic compound forms. CaF2

Properties of Ionic Compounds

Some common properties result form the strong forces of attraction holding the basic units together.

• High melting and boiling points• Hard, but brittle substances• Do not conduct electricity in the solid state.• Do conduct electricity in molten state.• Many dissolve in water and conduct electricity• Others…do not dissolve in water.

Polyatomic Ions• Group of covalently bonded atoms that have acquired

a positive or negative charge and form bonds with other ions.

Draw Lewis structures for:

NH4+ NO3

—

SO42- PO4

3-