Covalent Bonding - This type of bonding occurs typically between non-metal elements with an incomplete outer shell of electrons. Elements may share a pair of electrons in order to complete their outer shell and therefore increase their stability. An example of a compound that demonstrates covalent bonding is water (H2O) where the outermost shell in the oxygen has 6 electron initially and each of the hydrogens have 1 electron. By sharing a pair of electrons the hydrogen fills its outermost shell (has two electrons) and the oxygen atom gets an electron from each hydrgoen to have 8 electrons in its outershell. Ionic bonding - This type of bonding occurs between metal and non-metals elements which have either gained or lost electron to form charged ions. Non-metals typically gain electrons to complete their outershell and are therefore negatively charged ions whereas metals lose electrons in their outermost shell and are therefore positively charged ions. The ionic boding arises due to the electrostatic attraction between the oppositely charged ions.