Ac
Actinide
Actinium
Z 89A 227mass 227
Atomic model
tap a particleEvery nucleon is drawn individually — 89 protons and 138 neutrons packed into the nucleus, with 89 electrons on shells outside.
89+1
Protons
Set the element — change this and it becomes a different atom.
1380
Neutrons
Change only these and you get a different isotope of the same element.
89−1
Electrons
Sit outside the nucleus and decide the chemistry, not the element.
Element data
- Nucleons
- 227 (89 p + 138 n)
- Electron shells
- 2 · 8 · 18 · 32 · 19 · 8 · 2
- Valence shell
- 2 electrons
- Atomic mass
- 227 u
Stability
Actinium has no measured radioactive isotope in this lab — its nuclei are stable, so decay must be shown as an illustration.
Open the decay lab