Chemical bonds 6.3

In a crystal of sodium chloride, how many oppositely-charged ions does each Na+ and Cl- ion have clustered around it?

6

Compared with solid ionic compounds, solid molecular compounds generally

Have lower melting points.

Because strong attractive forces hold the layers in an ionic crystal in relatively fixed positions, ionic compounds

are hard and brittle.

The salts NaCl(s) and CaCl2(s)

are held together by ionic bonds

An ionic compound is not represented by a molecular formula because an ionic compound

lacks molecules

Compared with the energies of neutral atoms that form the ions, a crystal lattice has

lower potential energy

A charged group of covalently bonded atoms is known as a(n)

polyatomic ion

The arrangement of ions within a crystal structure and the strengths of the attractions between them vary with the

sizes and charges of different ions

Some ionic compounds do not dissolve in water because

the attractions between the water molecules and the ions are not as strong as the attractions between the ions.

The lattice energy is

the energy released when one mole of an ionic crystalline solid is formed from ions in the gas state.