Krypton

Symbol: Kr
Atomic number: 36
Category: noble gases
Group: 18
Period: 4
Block: p
Atomic weight: 83.798 g/mol
Electrons per shell: 2, 8, 18, 8
CAS number: 7439-90-9
Phase: gas
Density: 3.7494 g/l (0C, 101.325 kPa)
Melting point: 115.79 K (-157.36C, -251.25F)
Boiling point: 119.93 K (-153.22C, -244.12F)
Crystal structure: cubic face centered
Oxidation states: 4, 2
Electronegativity: 3.00 (Pauling scale)
Name's origin: kryptos
Name's meaning: a Greek word which means 'hidden' because it's found in trace amounts in the Earth's atmosphere
Facts:
- a colorless, odorless and tasteless noble gas
- is isolated by fractionally distilling liquified air
- is often used with other rare gases in fluorescent lamps
- has a brilliant green and orange spectral signature
- its concentration in the atmosphere is about 1 ppm
- little is known about whether krypton is dangerous, but it is treated as a non-toxic asphyxiant
- costs 100 times as much as argon