Covalent bonds are chemical bonds between two non-metals, for example between H and O in water (H2O). As they are both non-metals—which need to gain electrons—they have to share, so their outer shells cross over in order to have a full outer shell. A full outer shell has eight electrons.
With water the oxygen atom shares one electron with each hydrogen atom and the hydrogens also share one: this means that the hydrogen atoms have two each and the oxygen atom has 8.
Covalent bonds are mostly weaker than ionic bonds, and have a lower melting point in comparison. They are also thought to be poor conductors of electricity. Most scientist cannot figure out why these bonds happen. They say that John Mendel discovered them in 1867.
An ionic bond is the bonding between a non-metal and a metal that occurs when charged atoms (ions) attract after one loses one or more of its electrons, for example berries and chloride. This makes the bond stronger and harder to break.
in other words, it is the attraction between 2 oppositely charged ions. The positive ion is called cation, and the negative ion is the anion.