Oxygen

8
O
Group
16
Period
2
Block
p
Protons
Electrons
Neutrons
8
8
8
General Properties
Atomic Number
8
Atomic Weight
15.9994
Mass Number
16
Category
Other nonmetals
Color
Colorless
Radioactive
No
From the Greek word oxys, acid, and genes, forming
Crystal Structure
Base Centered Monoclinic
History
Carl Wilhelm Scheele obtained oxygen by heating mercuric oxide and nitrates in 1771, but did not publish his findings until 1777.

Joseph Priestley also prepared this new air by 1774.

The name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion.
Electrons per shell
2, 6
Electron Configuration
[He] 2s2 2p4
O
Green and red colors in the Aurora Borealis are caused by oxygen atoms
Physical Properties
Phase
Gas
Density
0.001429 g/cm3
Melting Point
54.36 K | -218.79 °C | -361.82 °F
Boiling Point
90.2 K | -182.95 °C | -297.31 °F
Heat of Fusion
0.222 kJ/mol
Heat of Vaporization
3.41 kJ/mol
Specific Heat Capacity
0.918 J/g·K
Abundance in Earth's crust
46%
Abundance in Universe
1%
Vial
Image Credits: Images-of-elements
Vial of glowing ultrapure oxygen
CAS Number
7782-44-7
PubChem CID Number
977
Atomic Properties
Atomic Radius
48 pm
Covalent Radius
66 pm
Electronegativity
3.44 (Pauling scale)
Ionization Potential
13.6181 eV
Atomic Volume
14.0 cm3/mol
Thermal Conductivity
0.0002674 W/cm·K
Oxidation States
-2, -1, 1, 2
Applications
Pure oxygen is frequently used to help breathing in patients with respiratory ailments.

Oxygen is used in oxyacetylene welding, as an oxidant for rocket fuel, and in methanol and ethylene oxide production.

It is also used in the production of steel, plastics and textiles.

Plants and animals rely on oxygen for respiration.
Oxygen gas can be toxic at elevated partial pressures, leading to convulsions and other health problems
Isotopes
Stable Isotopes
16O, 17O, 18O
Unstable Isotopes
12O, 13O, 14O, 15O, 19O, 20O, 21O, 22O, 23O, 24O, 25O, 26O, 27O, 28O