Symbol	O
Atomic number	8
Group	16 (Oxygen group)
Period	2
Block	p
Classification	Nonmetal

Appearance	-
Color	Colorless

Number of protons	8 p+
Number of neutrons	8 n0
Number of electrons	8 e-

From Wikipedia, the free encyclopediaOxygen is a chemical element with symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table and is a highly reactive nonmetal and oxidizing agent that readily forms compounds (notably oxides) with most elements. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium.

Phase at STP	Gas
Density	1.429 g/cm3
Atomic weight	15.999 u

Melting point	54.36 K -218.79 °C -361.822 °F
Boiling point	90.188 K -182.962 °C -297.3316 °F
Heat of vaporization	3.4109 kJ/mol

Electronegativity (Pauling Scale)	3.44
Electron affinity	140.976 kJ/mol
Oxidation states	−2, −1, 0, +1, +2 ()
Ionization energies	1313.9 kJ/mol 3388.3 kJ/mol 5300.5 kJ/mol 7469.2 kJ/mol 10989.5 kJ/mol 13326.5 kJ/mol 71330 kJ/mol 84078 kJ/mol

Electron configuration Shorthand configuration	[He] 2s2 2p4
Electron configuration Full configuration	1s2 2s2 2p4
Electron configuration chart	1s2 2s2 2p4
Electrons per shell	2, 6
Valence electrons	6
Valency electrons	2
Bohr model	Figure: Shell diagram of Oxygen (O) atom.
Orbital Diagram	1s 2s 2p

Discovery	Carl Wilhelm Scheele (1771)
First isolation	Antoine Lavoisier (1771)
Named by	Antoine Lavoisier
Discovery of oxygen Oxygen was isolated by Michael Sendivogius before 1604, but it is commonly believed that the element was discovered independently by Carl Wilhelm Scheele, in Uppsala, in 1773 or earlier, and Joseph Priestley in Wiltshire, in 1774. Priority is often given for Priestley because his work was published first. Priestley, however, called oxygen "dephlogisticated air", and did not recognize it as a chemical element. The name oxygen was coined in 1777 by Antoine Lavoisier, who first recognized oxygen as a chemical element and correctly characterized the role it plays in combustion. Lavoisier renamed 'vital air' to oxygène in 1777 from the Greek roots ὀξύς (oxys), because he mistakenly believed that oxygen was a constituent of all acids. Chemists (such as Sir Humphry Davy in 1812) eventually determined that Lavoisier was wrong in this regard, but by then the name was too well established.

CAS Number	7782-44-7
ChemSpider ID	140526
EC number	231-956-9
PubChem CID Number	977