About

Radon is a colorless, odorless, and radioactive noble gas. It is formed from the natural radioactive decay of uranium in soil, rock, and water. It can seep into buildings and accumulate to dangerous levels, being a significant cause of lung cancer after smoking. Medically, it has been used in radiation therapy, though this practice is now rare. It is the densest known gas.

Atomic Properties

Atomic Number86

Atomic Weight222 u

Neutrons (common)136

Electron Configuration[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶

Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶

Electrons per Shell2, 8, 18, 32, 18, 8

Electronegativity2.2

Oxidation States+2

Covalent Radius150 pm

Van der Waals Radius220 pm

Periodic Table Position

Group18

Period6

BlockP

Chemical SeriesNoble gases

Physical Properties

State at STPgas

Appearancecolorless radioactive gas

Crystal Structurefcc

Magnetic Orderingdiamagnetic

Speed of Sound180 m/s

Thermal Properties

Melting Point202 K

Boiling Point211.3 K

Triple Point202 K

Thermal Conductivity0.004 W/(m·K)

Specific Heat0.094 J/(g·K)

Molar Heat20.87 J/(mol·K)

Heat of Fusion2.89 kJ/mol

Heat of Vaporization16.4 kJ/mol

Abundance

In Earth's Crust0 ppm

In Ocean0 ppm

Discovery

Discovered byFriedrich Ernst Dorn

Discovery Year1,900

Occurrencefrom_decay

CAS Number10043-92-2

Electron Configuration

Energy

↿⇂

1s

↿⇂

2s

↿⇂

2p

↿⇂

3s

↿⇂

3p

↿⇂

4s

↿⇂

3d

↿⇂

4p

↿⇂

5s

↿⇂

4d

↿⇂

5p

↿⇂

6s

↿⇂

4f

↿⇂

5d

↿⇂

6p

7s

5f

6d

7p

Isotopes of Radon

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
²²²Rn	222.017570	Trace	3.8215 d	Alpha Decay