Promethium (chemical symbol: Pm) is a radioactive chemical element that is found in the lantanide group of metals. It has the atomic number 61 and an atomic weight of 145. It is very rare in nature and must be synthesized to obtain.

Characteristics – Promethium has an oxidation state of +3 and occurs as a soft, ductile metal. Its density is 7.26 g/cm3 and its melting temperature is 1100°C.

Properties – Promethium is the only chemical element that is totally radioactive. It degrades by producing alpha, beta and gamma rays. It degrades very rapidly and its degradation products are not stable.

Uses – Promethium is primarily used as an energy source in special atomic batteries, which power certain medical and space applications. In addition, its radioactivity is used in different types of analytical tests, as this allows specific elements to be identified. Finally, it is used in certain medical studies and radiotherapy applications.

1080°
2730°

145

[Xe] 4f5 6s2

2
8
18
23
8
2

1.13

5.582

Synthetic

Radioactive

Liquid

Gaseous

Electronic configuration diagram

Characteristics

Name	Promethium
Number	61
Atomic	145
Symbol	Pm
Fusion	1080
Boiling	2730
Density	7.26
Period	6
Group	0

Discovery	1945 Marinsky et al.
Abundance	0.001
Radius	2.6
Electronegativity	1.13
Ionization	5.582
Number of isotopes	14
Electronic configuration	[Xe] 4f5 6s2
Oxidation states	3
Electron by energy level	2,8,18,23,8,2