Fm
Actinide
Fermium
Z 100A 257mass 257
Atomic model
tap a particleEvery nucleon is drawn individually — 100 protons and 157 neutrons packed into the nucleus, with 100 electrons on shells outside.
100+1
Protons
Set the element — change this and it becomes a different atom.
1570
Neutrons
Change only these and you get a different isotope of the same element.
100−1
Electrons
Sit outside the nucleus and decide the chemistry, not the element.
Element data
- Nucleons
- 257 (100 p + 157 n)
- Electron shells
- 2 · 8 · 18 · 32 · 30 · 8 · 2
- Valence shell
- 2 electrons
- Atomic mass
- 257 u
Stability
Fermium has no measured radioactive isotope in this lab — its nuclei are stable, so decay must be shown as an illustration.
Open the decay lab