Tm
Lanthanide
Thulium
Z 69A 169mass 168.93
Atomic model
tap a particleEvery nucleon is drawn individually — 69 protons and 100 neutrons packed into the nucleus, with 69 electrons on shells outside.
69+1
Protons
Set the element — change this and it becomes a different atom.
1000
Neutrons
Change only these and you get a different isotope of the same element.
69−1
Electrons
Sit outside the nucleus and decide the chemistry, not the element.
Element data
- Nucleons
- 169 (69 p + 100 n)
- Electron shells
- 2 · 8 · 18 · 31 · 8 · 2
- Valence shell
- 2 electrons
- Atomic mass
- 168.93 u
Stability
Thulium has no measured radioactive isotope in this lab — its nuclei are stable, so decay must be shown as an illustration.
Open the decay lab