Ionic bonding is usually formed between a metal and a non-metal, Covalent between two non-metals and Metallic between two metals.
Ionic Bonding; Ionic bonds tend to form between metals whose atoms need to “loose” electrons to gain the nearest noble gas configuration and non-metals that need to gain electrons. These electrons are transferred from one atom to another. This gives one ion a positive charge and the other a negative one.
The Opposite charges in the ion hold them together in a regular three dimensional lattice by electrostatic attractions; the arrangement of the ions in a crystalline lattice depends on the relative size of the ions.
These electrostatic attractions are strong and this means that a large amount of energy is needed to overcome them and separate the ions, as a result of these ionic compounds have very high melting points.
Any dislocation leads to the layers of the lattice moving and similar charges being adjacent, these charges repel each other splitting the crystal. This means that ionic compounds are very brittle.
Ionic compounds do not conduct when a solid because the ions are held together strongly in their lattice structure, this means that the ions are not free to move and therefore not free to move and carry a charge. However when molten or in aqueous solution the ions become mobile and conduction can take place.
Ionic compounds are soluble because of their charge. The Polar nature of water (unequal shared charges throughout the molecule) means that the water molecules attract the charged ions eventually breaking the charged molecules away from the lattice to form hydrogen bonds with the water molecules. And therefore dissolving.
Covalent bonding; Consists of shared pairs of electrons with one electron being supplied by each atom either side of the bond. Atoms