Chemistry Elements, Atoms and Molecules Why Chemistry? Nature is not neatly packaged into the individual life sciences. Biology is a multidisciplinary science, drawing on the insights from other sciences. Essential Elements 96.3% of living matter O = 65%, C = 18.5%, H = 9.5%, N = 3.3% 3.7% Ca, P, K, S, Na, Cl, Mg trace elements (