Chemistry

Ionic Lattice

An ionic bond is a type of chemical bond that involves a metal and a non-metal ion bonding through electrostatic attraction.   Therefore it is a bond formed by the attraction between two oppositely charged ions.

The metal donates one of more electrons, forming a positively charged ion or cation with a stable electronic configuration.   These donated electrons then enter the non-metal, causing it to form a negatively charged ion or anion, which also has a table electronic configuration

Ionic compounds conduct electricity when molten or in a solution.   They generally have a high melting point and tend to be soluble in water.

In an ionic solid, the ions are packed together in a repeating array called a crystal lattice.   The easiest way to picture such an array is to arrange one layer of spheres and then place successive layers over it.   The two principle factors in determining the form of the lattice used are the relative charges of the ions and their relative sizes.   Ionic lattices assume the shape of simple cubic packing, body-centered cubic, hexagonal packing and cubic close-packing arrangements.

The simplest of these arrangements is one in which the spheres in the base are packed side by side.   The successive layers of spheres are then added directly over the spheres of the layer below.   This is known as simple cubic packing.

An alternative arrangement can be obtained by placing the second layer of spheres over the holes of the base layer.   The third layer of sphere are placed over the holes of layer two with successive layers added in the same manner.   This type of array is known as the body-centered cubic.

In hexagonal packing arrangements the third layer is superimposed over the first layer and in cubic-close packing arrangements the third layer is placed over voids in both underlying layers.

An example of an ionic lattice is the structure formed by Sodium Chloride:

Covalent Molecules
Covalent molecules are formed...