| Content-Type | image/png |
|---|---|
| Content-Length | 3.96 kB |
| Size | 512x512 |
#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