Helium
Helium (symbolo He) es le elemento chimic con numero atomic 2.
Su peso atomic es 4,002602. Illo es un incolor, inodor, insipide, nontoxic, inerte, monatomic gas que conduce le gruppo de gases nobile in le tabella periodic del elementos. Su punctos de ebullition e fusion es le plus basse del elementos, e illo existe solmente como un gas, excepte in conditiones extreme. Juxta hydrogeno, illo es le secunde plus abundante elemento in le universo, e da conto de 24% del massa elemental de nostre galaxia.
| Hydrogeno ← Helium → Lithium | |
| Apparentia | |
 | |
| gas incolor, que ha un brillantia rubie-orange in un campo electric de alte voltage | |
| Proprietates atomic | |
| Nomine, symbolo, numero | Helium, He, 2 |
| Serie chimic | gas nobile |
| Gruppo, periodo, bloco | 18, 1, s |
| Configuration electronic | 1s2 |
| Proprietates physic | |
| Stato | gas |
| Massa molar | 4,002602 g·mol-1 |
| Densitate | 0,1786 g/L (0 °C, 101,325 kPa) |
| Densitate liquide al p.f. | 0,145 g·cm−3 |
| Puncto de fusion | 0,95 K, -272,20 °C, -457.96 °F |
| Puncto de ebullition | 4,22 K, -268,93 °C, -452.07 °F |
| Puncto triple | nulle |
| Puncto critic | 5,19 K, 0,227 MPa |
| Calor de fusion | 0,0138 kJ·mol-1 |
| Calor de vaporisation | 0,0829 kJ·mol-1 |
| Calor specific | 20,786 J·mol-1·K-1 (25 °C) |
| Conductivitate thermal | 0,1513 W·m−1·K−1 |
| Velocitate de sono | 972 m/s (0 °C) |
| Valores in unitates SI e in le conditiones normal del material (25 °C, 100 kPa) si non indica al contrario. | |
Vide etiam
Referentias
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