With two unpaired electrons, O 2 is a triplet in the ground state. Upon the absorption of light in the visible region between 400-700 nm, all the electrons become paired in the singlet oxygen excited state. After red light is emitted, the oxygen turns back to blue. Alkali and alkaline earth metals form oxides. The lower the number, the more basic the compound.
Some amphoteric oxides react with both acids and bases.
Hydrogen is the most abundant element in the universe. N 2 is the most abundant in the atmosphere. O 2 is the most abundant on earth. Dueterium has an atomic mass of 2 due to one proton and one neutron. Tritium has an atomic mass of three due to 2 neutrons and 2 proton.