Periodex

General properties

Group

group 16 (chalcogens)

Period

period 2

Category

nonmetals

Standard atomic weight

15.999

[15.999 03, 15.999 77]

Melting point

(O₂) 54.36 K (-218.79 °C)

Boiling point

(O₂) 90.188 K (-182.962 °C)

Phase at STP

gas

Additional properties

Block

p-block

Electron configuration

[He] 2s² 2p⁴

Electrons per shell

2, 6

Electronegativity

3.44

Density

1.429 g/L

Oxidation states

−2, −1, 0, +1, +2

CAS Number

7782-44-7

Natural isotopes

Discovery history

Discovered by

Carl Wilhelm Scheele

Year of discovery

1771

Origin of name

The Greek 'oxy' and 'genes' meaning acid-forming