1. Living matter is composed mostly of the lighter elements 1.1 The composition of living matter is striking different from that of its physical environment (1810s 1. 2 The elements found in living organisms also exist in nature(especially in seawater and atmosphere). 1.2.1 99 of the mass of living organisms are made ofh. o.n. and c 1.2.2 H, O, N, and c are the lightest elements capable of forming one, two, three, and four bonds (in general, lightest elements form the strongest bonds) 1.2.3 The trace elements, although represent a miniscule fraction in living organisms, all are absolutely essential to life(Fe, Cu, Mn, Zn, L, Mg).1. Living matter is composed mostly of the lighter elements 1.1 The composition of living matter is strikingly different from that of its physical environment (1810s) 1.2 The elements found in living organisms also exist in nature (especially in seawater and atmosphere). 1.2.1 99% of the mass of living organisms are made of H, O, N, and C. 1.2.2 H, O, N, and C are the lightest elements capable of forming one, two, three, and four bonds (in general, lightest elements form the strongest bonds). 1.2.3 The trace elements, although represent a miniscule fraction in living organisms, all are absolutely essential to life (Fe, Cu, Mn, Zn, I, Mg)