Barium

Symbol	Ba
Atomic number	56
Group	2 (Alkaline earth metal)
Period	6
Block	s
Classification	Alkaline Earth Metal

Appearance	-
Color	Silver

Number of protons	56 p+
Number of neutrons	81 n0
Number of electrons	56 e-

From Wikipedia, the free encyclopediaBarium is a chemical element with symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Because of its high chemical reactivity barium is never found in nature as a free element.

Phase at STP	Solid
Density	3.51 g/cm3
Atomic weight	137.328 u

Melting point	1000 K 726.85 °C 1340.33 °F
Boiling point	2118 K 1844.85 °C 3352.73 °F
Heat of vaporization	140.2 kJ/mol

Electronegativity (Pauling Scale)	0.89
Electron affinity	13.954 kJ/mol
Oxidation states	+1, +2 (a strongly basic oxide)
Ionization energies	502.9 kJ/mol 965.2 kJ/mol 3600 kJ/mol

Electron configuration Shorthand configuration	[Xe] 6s2
Electron configuration Full configuration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 6s2
Electron configuration chart	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 6s2
Electrons per shell	2, 8, 18, 18, 8, 2
Valence electrons	2
Valency electrons	2
Bohr model	Figure: Shell diagram of Barium (Ba) atom.
Orbital Diagram	1s 2s 2p 3s 3p 3d 4s 4p 4d 5s 5p 6s

Discovery	Carl Wilhelm Scheele (1772)
First isolation	Humphry Davy (1808)
Named by	Humphry Davy (1808)
Discovery of barium Alchemists in the early Middle Ages knew about some barium minerals. Smooth pebble-like stones of mineral baryte were found in volcanic rock near Bologna, Italy, and so were called "Bologna stones". Alchemists were attracted to them because after exposure to light they would glow for years. The phosphorescent properties of baryte heated with organics were described by V. Casciorolus in 1602. Carl Scheele determined that baryte contained a new element in 1774, but could not isolate barium, only barium oxide. Johan Gottlieb Gahn also isolated barium oxide two years later in similar studies. Oxidized barium was at first called "barote" by Guyton de Morveau, a name that was changed by Antoine Lavoisier to baryta. Barium was first isolated by electrolysis of molten barium salts in 1808 by Sir Humphry Davy in England. Davy, by analogy with calcium, named "barium" after baryta, with the "-ium" ending signifying a metallic element.

Original word	barys
Language of origin	Greek
Name source	Properties
Meaning	“Heavy”
Naming The name comes from the Greek word 'barys', meaning heavy, because of the high density of barium-rich minerals such as baryta.

CAS Number	7440-39-3
ChemSpider ID	4511436
EC number	231-149-1
PubChem CID Number	5355457