Primordial Elements

Elements and isotopes formed in the Big BangBeginning point of time and space for the universe. A state of extremely high (classically, infinite) density and temperature from which the universe began expanding. Click on Term to Read More including: hydrogenLightest and most common element in the universe (~92% by atoms; ~75% by mass). Hydrogen's isotopes are: • ¹H (99.9885 %)
• ²H (0.0115 %), also called deuterium.
• ³H, also called Tritium, is a radioactive (t½ = 12.32 y) by-product of atmospheric thermonuclear tests in Earth's hydrosphere and atmosphere.
Click on Term to Read More (¹H), heliumHelium (He) Second lightest and second most abundant element (after Hydrogen) in the universe. The most abundant isotope is 4He (99.9998%), 3He is very rare. Helium comprises ~8% of the atoms (25% of the mass) of all directly observed matter in the universe. Helium is produced by hydrogen burning inside Click on Term to Read More (³He, ⁴He), most 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 (²H) and tritium (³H), and some lithium (⁷Li).