This tutorial introduces the very important concept of electronegativity. We look at the trends throughout the periodic table with fluorine being the most electronegative element. The Pauling scale is used to quantify every element but it is generally non-metals that are discussed. From this theory we get polar and non-polar bonds . Furthermore, simple covalent molecules can exist as polar or non-polar molecules e.g. CH4, CO2, CHCl3 i.e. a molecule can be non-polar but still contain polar bonds.