61
Pm
145
Promethium (Pm)
Element 61 · Period 6 · Lanthanide series
lanthanide
solid at room temp
f-block
radioactive
About Promethium
Radioactive lanthanoid. Used in nuclear batteries and luminous paint.
Physical Properties
Atomic Mass
145 u
State at 25°C
Solid
Melting Point
1042 °C
Boiling Point
3000 °C
Density
7.26 g/cm³
Magnetism
Paramagnetic
Atomic Properties
Electron Configuration
[Xe] 4f⁵ 6s²
Electron Shells
2, 8, 18, 23, 8, 2
Electronegativity
1.13
Atomic Radius
236 pm
Ionization Energy
540 kJ/mol
Oxidation States
+3
Discovery & History
Discovered By
J.A. Marinsky
Discovery Year
1945
Named By
J.A. Marinsky
Name origin: Greek myth: Prometheus
Frequently Asked Questions
- Is Promethium a metal, nonmetal, or metalloid?
- Promethium is classified as a lanthanide.
- What state is Promethium in at room temperature?
- Promethium is a solid at standard room temperature (25°C).
- What is the atomic mass of Promethium?
- Promethium has an atomic mass of 145 atomic mass units (u).
- Who discovered Promethium?
- Promethium was discovered by J.A. Marinsky in 1945.
- Where is Promethium on the periodic table?
- Promethium is element number 61, located in period 6, part of the lanthanide series shown below the main table.