NGC 604, a giant region of ionized hydrogen in the Triangulum Galaxy Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of 1.00794 u (1.007825 u for hydrogen-1), hydrogen is the lightest and most abundant chemical element, constituting…

Helium discharge tube shaped like the element's atomic symbol Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic…

Carbon dioxide bubbles in a soft drink. Carbon dioxide (chemical formula CO2) is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state, as a trace…

Liquid nitrogen Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere. The element nitrogen was discovered as a…

Oxygen is the element with atomic number 8 and represented by the symbol O. At standard temperature and pressure, oxygen is a very pale blue, odorless gas with the molecular formula O2, in which the two oxygen atoms are chemically bonded to each other with a spin triplet electron configuration.…