Pm
Lanthanide
Promethium
Z 61A 145mass 145
Atomic model
tap a particleEvery nucleon is drawn individually — 61 protons and 84 neutrons packed into the nucleus, with 61 electrons on shells outside.
61+1
Protons
Set the element — change this and it becomes a different atom.
840
Neutrons
Change only these and you get a different isotope of the same element.
61−1
Electrons
Sit outside the nucleus and decide the chemistry, not the element.
Element data
- Nucleons
- 145 (61 p + 84 n)
- Electron shells
- 2 · 8 · 18 · 23 · 8 · 2
- Valence shell
- 2 electrons
- Atomic mass
- 145 u
Stability
Promethium has no measured radioactive isotope in this lab — its nuclei are stable, so decay must be shown as an illustration.
Open the decay lab