the visible spectrum of atomic helium.

He - Helium

A light inert gas and the second most abundant element in the universe. Helium was discovered in 1868 by J. Norman Lockyear in the spectrum of a solar eclipse. Our students encounter helium carrier gas with the chromatograph instruments and observe its discharge spectrum.

Atomic number - 2 Density g/mL 0 .00001787
Atomic weight u 4 .0026 Melting point K 0 .95
Bonding radius A 0 .93 Boiling point K 4 .215
Atomic radius A 0 .49 Heat of vaporization kJ/mol 0 .0845
Ionization Potential V 24 .587 Heat of fusion kJ/mol -
Electronegativity - - Specific heat J/gK 5 .193
The oxide is unknown.
Crystal are hexagonal.

Electron config. : 1s2

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Ac** Rf Db Sg Bh Hs Mt 110 111 112 113
Lanthanides* Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Actinides ** Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

Isotopes of He: Click mass number for decay process, product for element page.
003 0.000137%

Stable

3.0160293 		004 99.999863%

Stable

4.0026032 		005
0.60 MeV
a/n,2.980 MeV
n/He-4
5.0122276 		006
806.7 msec
B-,3.508 MeV
Li-6
6.0188880 		007
160KEV
n,1.372 MeV
He-6
7.0280302 		008
119.0 msec
B-/B-n,10.653
Li-8/Li-7
8.0339218 		009
0.3 MeV
n,1.150 MeV
He-8
9.0438220
010
0.3 MeV
n,16.775 MeV
He-9
10.052399 		MASS abund.
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass

Updated by clh on 2/6/98. This is not a publication of Phoenix College.