Hydrogen
Lightest and most common elementSubstance composed of atoms, each of which has the same atomic number (Z) and chemical properties. The chemical properties of an element are determined by the arrangement of the electrons in the various shells (specified by their quantum number) that surround the nucleus. In a neutral atom, the number of Click on Term to Read More in the universeThat which contains and subsumes all the laws of nature, and everything subject to those laws; the sum of all that exists physically, including matter, energy, physical laws, space, and time. Also, a cosmological model of the universe. (~92% by atoms; ~75% by mass). Hydrogen’s isotopes are:
- 1H (99.9885 %)
- 2H (0.0115 %), also called deuteriumAlso called heavy hydrogen, deuterium is an isotope of hydrogen (D, or 2H) whose nucleus contains one proton and one neutron. As a trace element formed during the nucleosynthesis epoch of the Big Bang, deuterium is an important indicator of the baryon density in the universe. The larger the density, the Click on Term to Read More.
- 3H, also called Tritium, is a radioactive (t½ = 12.32 y) by-product of atmospheric thermonuclear tests in Earth’s hydrospherePortion of a planet that is water, including liquid water, ice, and water vapor on the surface, underground, or in the atmosphere. Click on Term to Read More and atmosphere.
