Atomic # = 8
Atomic weight = 15.9994
Oxygen is necessary for the combustion (burning) of carbon-containing fuels. For example, the combustion of methane is represented by:
CH4 (g) + 2 O2 (g) –> CO2 (g) + 2 H2O (g)
Combustion of carbon-containing fuels is the primary source of energy for a variety of processes on earth. Oxygen is also required for the process of respiration, which provides energy for living things:
C6H12O6 + 6 O2 –> 6 CO2 (g) + 6 H2O (g)