THE ELEMENTS OF YOU

摘要

By sheer weight of numbers, there is a clear answer to the question "what are you made of?". Over 60 per cent of all the atoms in your body are hydrogen, the lightest in the periodic table. Go by overall mass, however, and the leader is oxygen. Oxygen largely comes in molecules bound to other things, notably with hydrogen as water (H_2O). We tend to define ourselves with reference to the element that is second in terms of mass, however, because it is so crucial to the body's chemistry and structural integrity: we say we are carbon-based life forms.