Primordial elements are chemical elements found on the earth that have existed in their current form since before the earth was formed, according to the big bang theory. This means that the half-life on the given atoms must be greater than about 4.5×10⁹ years. The mass of the atom is also very important. Heavier atoms would need longer half lives to be primordial because lighter elements are formed more often in stellar reactions. A chemical element, often called simply element, is a chemical substance that cannot be divided or changed into other chemical substances by any ordinary chemical technique. ... According to the Big Bang theory, the universe originated in an infinitely dense and physically paradoxical singularity. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ...

Hydrogen, helium (both helium-3 and helium-4), most deuterium, and some lithium-7 are examples of primordial elements. General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance of one atom in 6500 of hydrogen. ... General Name, Symbol, Number Lithium, Li, 3 Series Alkali metal Group, Period, Block 1(IA), 2, s Density, Hardness 535 kg/m3, 0. ...