Barium (Ba) » Innovachem

Isotope	Z(p)	N(n)	Atomic Mass	Natural Abundance	Enrichment Level	Chemical Form
Ba-132	56	76	131.905056	0.10%	12.80-40.70%	Carbonate
Ba-134	56	78	133.904504	2.42%	88.00%	Carbonate
Ba-135	56	79	134.905684	6.59%	>94.00%	Carbonate
Ba-136	56	80	135.904571	7.85%	61.00-95.40%	Carbonate
Ba-137	56	81	136.905822	11.23%	91.70%	Carbonate
Ba-138	56	82	137.905242	71.70%	99.80%	Carbonate

Name	Barium
Symbol	Ba
Atomic number	56
Atomic weight	137.327
Standard state	Solid at 298 ºK
CAS Registry ID	7440-39-3
Group in periodic table	2
Group name	Alkaline earth metals
Period in periodic table	6
Block in periodic table	s-block
Color	Silvery white
Classification	Metallic
Melting point	727 °C
Boiling point	1845 °C
Vaporization point	1897 ºC
Thermal conductivity	18.4 W/(m·K)
Electrical resistivity	332 µΩ·cm at 20°C
Electronegativity	0.9
Heat of vaporization	140.3 kJ·mol^-1
Heat of fusion	8 kJ·mol^-1
Density of liquid	3.338 g/cm³
Density of solid	3.51 g/cm³
Electron configuration	[Xe]6s²
Atomic radius	222 pm
Ionic radius	Ba²⁺ in crystal: 1.42 Å (coordination number 8)
Oxidation state	+2
First ionization potential	10.00 eV