Helium (He)

   

Helium (He)

Helium

Latin name: Helium

English name: Helium

Year discovered: 1895

CAS Number: CAS7440-59-7

Discovered by: Pierre Jules César Janssen                            Joseph Norman Lockyer

Cost per 100 grams: 2.4 USD

Electron shell: K2 L0 M0 N0 O0 P0 Q0 R0 

Electrons: 2

Protons: 2

Neutrons: 2

Atomic number: 2

Atomic weight (Relative atomic mass): 4.0026 (g/mol)

Density: 0.00017846 (g/cm³)

Melting point: -272.2°C   =   -457.96°F   =   0.95K

Boiling point: -268.9°C   =   -452.02°F   =   4.25K

Phase: Gas

Valence: 0

Period: 1

Group: VIIIA

Block: s – block

Magnetic type: Diamagnetism

Crystal structure: Hexagonal close-packed

Grid parameters: a=3.570 Å; c=5.84 Å

Attitude: 1.633

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