Chemicool

He

2

4.00260
Helium
General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles

General
Name Helium Symbol He
atomic number 2 Atomic weight 4.00260
Density @ 293 K 0.0001787 g/cm3 Atomic volume ?
Group Noble Gas discovered 1895

States
state (s, l, g) g
melting point K boiling point 4.2 K
Heat of fusion ? Heat of vaporization 0.0845 kJ/mol
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Energies
1st ionization energy 2372.3 kJ/mole electronegativity
2nd ionization energy 5250.3 kJ/mole electron affinity 0 kJ/mole
3rd ionization energy kJ/mole Specific heat 5.193 J/gK
heat atomization 0 kJ/mole atoms

Oxidation & Electrons
Shells 2 electron configuration 1s2
minimum oxidation number 0 maximum oxidation number 0
min. common oxidation no. 0 max. common oxidation no. 0
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Appearance & Characteristics
structure color colorless
uses cryogenics, blimps toxicity no
hardness mohs characteristics Inert, dens

Reactions
reaction with air none reaction with 6M HCl none
reaction with 6M HCl none reaction with 15M HNO3 none
reaction with 6M NaOH none
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Other Forms
number of isotopes 2 hydride(s) none
oxide(s) none chloride(s) none

Radius
ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius 31 pm ionic radius (1+ ion) pm
ionic radius (2+ ion) pm ionic radius (3+ ion) pm
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Conductivity
thermal conductivity 0.15 J/m-sec-deg electrical conductivity 1/mohm-cm
polarizability 0.198 A^3

Abundance
source Natural gas, air rel. abund. solar system 9.435 log
abundance earth's crust -2.1 log cost, pure 5.2 $/100g
cost, bulk $/100g
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