Pm
145.000Promethium
Prometyum
Promethium is a radioactive lanthanide with atomic number 61. It has no stable isotopes, occurs only in trace natural amounts and is known for promethium-147 beta sources, nuclear battery research and portable X-ray source history.
61
145 g/mol
[Xe] 4f⁵ 6s²
2 | 8 | 18 | 23 | 8 | 2
1.13
7.26 g/cm³
1041.8 °C
2999.8 °C
Marinsky, Glendenin & Coryell
Promethium was identified in 1945 by Jacob A. Marinsky, Lawrence E. Glendenin and Charles D. Coryell while separating uranium fission products at Oak Ridge. Its name comes from Prometheus, the Titan who stole fire for humanity.
Promethium-145
Half-life: About 17.7 years. One of the longest-lived promethium isotopes; decays mainly by electron capture.Promethium-146
Half-life: About 5.5 years. Radioactive isotope used in research context.Promethium-147
Half-life: About 2.623 years. Beta-emitting isotope and the main practical promethium isotope.Pm₂O₃
Promethium(III) OxideRadioactive lanthanide oxide used in research.PmCl₃
Promethium(III) ChlorideResearch precursor for promethium compounds.- Promethium-147 beta sources for thickness gauges and specialized industrial measurement
- Historic nuclear battery and luminous paint research, now limited by radioactivity and availability
- Portable X-ray and radiation-source research using promethium radioisotopes
- Scientific studies of radioactive lanthanide chemistry and beta-emitting materials
Promethium has no biological role. All promethium isotopes are radioactive, so biological exposure is treated as a radiological hazard rather than as normal trace-element chemistry.
- Promethium and technetium are the only elements below bismuth with no stable isotopes.
- Natural promethium exists only in extremely tiny amounts from uranium and thorium decay or fission processes.
- Promethium-147 is a beta emitter, which made it attractive for thickness gauges and experimental nuclear batteries.
- The Prometheus name fits an element tied to nuclear energy and artificial production.
- Promethium has atomic number 61 and is a lanthanide.
- Its electron configuration is [Xe] 4f⁵ 6s².
- Promethium has no stable isotopes; this is the key exam and reference fact.
- Connect Pm-147 with beta sources, thickness gauges and historical nuclear battery ideas.
What is the atomic number of promethium?
The atomic number of promethium is 61.
What is the electron configuration of promethium?
Promethium has the electron configuration [Xe] 4f⁵ 6s².
Does promethium have stable isotopes?
No. All promethium isotopes are radioactive.
What is promethium-147 used for?
Promethium-147 is used or studied as a beta source for thickness gauges, radiation-source devices and historical nuclear battery applications.
Is promethium natural or synthetic?
Promethium is mostly produced artificially, although trace natural amounts can form from uranium and thorium processes.
Why is promethium named after Prometheus?
The name refers to Prometheus from Greek mythology and reflects the element’s connection with nuclear energy and discovery from fission products.