69 - Thulium lanthanide
Discovered by Per Teodor Cleve in 1879
Thulium is a chemical element with symbol Tm and atomic number 69. It is the thirteenth and antepenultimate (third-last) element in the lanthanide series. Like the other lanthanides, the most common oxidation state is +3, seen in its oxide, halides and other compounds.
Periodic table
| Shell | Electrons | Orbitals |
|---|---|---|
| 1 | 2 | 2 in 1s |
| 2 | 8 | 2 in 2s + 6 in 2p |
| 3 | 18 | 2 in 3s + 6 in 3p + 10 in 3d |
| 4 | 31 | 2 in 4s + 6 in 4p + 10 in 4d + 13 in 4f |
| 5 | 8 | 2 in 5s + 6 in 5p |
| 6 | 2 | 2 in 6s |
Electron shells
silvery gray Appearance
169 u Atomic Mass
1.75 Å Atomic Radius
2.22k K Boiling Point
15 Group
3 Common Oxidation States
1.9 Å Covalent Radius
9.32 g/cm³ Density
99 kJ/mol Electron Affinity
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f13 Electron Configuration
[Xe] 4f13 6s2 Electron Configuration (semantic)
1.25 Electronegativity
69 Electrons
6.18 eV First Ionization Energy
3 ICSD Oxidation States
596.7, 1160, 2285, 4120 kJ/mol Ionization Energies
1.82k K Melting Point
21 Mendeleev Number
27 J/(mol·K) Molar Heat
6 Number of Shells
100 Neutrons
69 Atomic Number
18 Number of Isotopes
2, 3 Oxidation States
6 Period
Solid Phase
69 Protons
2, 8, 18, 31, 8, 2 Electron Shell Occupations