User:Hydrogen astatide/He

Hydrogen astatide/He, ₀₀He

Hydrogen astatide/He
Pronunciation	/ˈhiːliəm/ ​(HEE-lee-əm)
Standard atomic weight Ar°(He)
	4.002602±0.000002 4.0026±0.0001 (abridged)
{{{name}}} in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson {{{above}}} ↑ He ↓ {{{below}}} {{{left}}} ← {{{name}}} → {{{right}}}
Group	group 18 (noble gases)
Period	period 1
Block	s-block
Electron configuration	1s2
Physical properties
Phase at STP	gas
Melting point	69 K ​(69 °C, ​69 °F)
Boiling point	69 K ​(69 °C, ​69 °F)
Atomic properties
Oxidation states	common: (none)
Spectral lines of
Other properties
Natural occurrence	primordial
[[Isotopes of {{{name}}}]]
Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 232U synth 68.9 y α 228Th SF – 233U trace 1.592×105 y α 229Th SF – 234U 0.005% 2.455×105 y α 230Th SF – 235U 0.720% 7.038×108 y α 231Th SF – 236U trace 2.342×107 y α 232Th SF – 238U 99.3% 4.468×109 y α 234Th SF – β−β− 238Pu