Mendeleev's Periodic Table > H - Hydrogen

H - Hydrogen

Henry Cavendish discovered that hydrogen was an element in 1766. Hydrogen is the lightest element. It is by far the most abundant element in the universe and makes up about about 90% of the universe by weight. Hydrogen as water (H2O) is absolutely essential to life and it is present in all organic compounds. Hydrogen is a very flammable element

Atomic number - 1 Density g/mL 0 .00008987
Atomic weight u 1 .0079 Melting point K 14 .025
Bonding radius A 0 .32 Boiling point K 20 .268
Atomic radius A 0 .79 Heat of vaporization kJ/mol 0 .44936
Ionization Potential V 13 .598 Heat of fusion kJ/mol 0 .05868
Electronegativity - 2 .2 Specific heat J/gK 14 .304
The oxide is amphoteric. Crystal are hexagonal.
Electron config. : 1s1

Isotopes of H (Hydrogen):

MASS abundancy
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass		 001 99.985%

Stable
1.0078250 		002 0.015%

Stable
2.0141017 		003
12.33 yr
B-
He-3
3.0160492 		004
5.42 yr
n,2.980 MeV
H-3
4.0279121