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


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


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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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


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


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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thermal conductivity 0.15 J/m-sec-deg electrical conductivity 1/mohm-cm
polarizability 0.198 A^3


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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World Wide Web presentation of Chemicool Periodic Table is © Copyright 1996-99 by David D. Hsu. Some data were provided by and used with the permission of JCE Software and is owned and copyright by the Division of Chemical Education, Inc. Additional data were provided by Perkin-Elmer through Peter Lykos of IIT. The information may not be redistributed without the permission of David Hsu or JCE Software.