Changes

==Chemical Properties==

==Chemical Properties==

At normal pressures hydrogen melts at 14.01[[Kelvin]] (K) and boils at 20.28K, essentially meaning that it only exists on Earth as a gas. The near-vacuum of interstellar space means that hydrogen is also a gas under these circumstances. Astronomers and chemists hypothesise that hydrogen exists as a plasma inside stars and possibly in a metallic form in the cores of gas giant [[planets]] such as [[Jupiter]].

At normal pressures hydrogen melts at 14.01[[Kelvin]] (K) and boils at 20.28K, essentially meaning that it only exists on Earth as a gas. The near-vacuum of interstellar space means that hydrogen is also a gas under these circumstances. Astronomers and chemists hypothesise that hydrogen exists as a plasma inside stars and possibly in a metallic form in the cores of gas giant [[planets]] such as [[Jupiter]]. The most common form of hydrogen is molecular hydrogen, consisting of two atoms bonded by a single hydrogen bond. The chemical symbol for molecular hydrogen is H₂.

==Isotopes==

==Isotopes==