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#2 Helium - rarity ZERO-KELVIN
1st ionization energy 24.587 eV 0.85%
appearance Colorless gas 7.63%
atomic mass 4.002 u 0.85%
atomic number 2 0.85%
atomic radius 140 picometers (van der Waals radius) 1.69%
boiling point 4.22 K or -268.9 °C or -452 °F 0.85%
cas number 7440-59-7 0.85%
cas number of (cl2) - 99.15%
category Noble gases 5.08%
crystal structure HCP (Hexagonal closed packing) 3.39%
density 0.1786 g/L 0.85%
electronegativity - 21.19%
electronic configuration 1s2 0.85%
electrons 2 0.85%
electrons arrangement 2 electrons in 1st shell 0.85%
main isotopes 4He 0.85%
melting point 0.95 K or -272.2 °C or -457.9 °F (at 2.5 MPa) 0.85%
neutrons 2 0.85%
position Group: 18, Period: 1, Block: p 0.85%
rarity ZERO-KELVIN 33.33%
state Gas 9.32%
sublimation point - 99.15%
symbol He 0.85%
valence electrons 2 7.63%
who discovered 1). Pierre Jules César Janssen, and 2). Sir Joseph Norman Lockyer(Discovered in 1868) 0.85%

Total Rarity Score: 1924.85

Rarity: #64/354

Helium

Collection: Bohring Atoms