69 Tm 168.934

Thulium

lanthanide

Properties

Atomic number
69
Atomic mass
168.934 u
Category
lanthanide
Group
f-block
Period
6
Block
f-block
State (room temp)
Solid
Outer-shell electrons
2
Electronegativity
1.25 (Pauling)
Density
9.32 g/cm³
Melting point
1544.85 °C
Boiling point
1949.85 °C

Electron configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹³

Noble-gas shorthand: [Xe] 4f¹³ 6s²

Electrons per shell: 2, 8, 18, 31, 8, 2, which is 2 in the outermost shell.

Related: electron configuration, the Bohr model, valence electrons.

Tm
Bohr model; outer-shell electrons in blue

About Thulium

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.

Thulium: frequently asked questions

What is Thulium?
Thulium (Tm) is the chemical element with atomic number 69. It is a metal: specifically a lanthanide.
What is the atomic number of Thulium?
Thulium's atomic number is 69, which means every Thulium atom has 69 protons in its nucleus.
What is the electron configuration of Thulium?
The electron configuration of Thulium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f13 (noble-gas shorthand: [Xe] 4f13 6s2). Its electrons are arranged in shells of 2, 8, 18, 31, 8, 2, with 2 in the outermost shell.
Is Thulium a metal or a nonmetal?
Thulium is a metal: specifically a lanthanide.
What group and period is Thulium in?
Thulium sits in the f-block (the lanthanide row) of period 6 on the periodic table.
Is Thulium a solid, liquid, or gas?
At room temperature, Thulium is a solid.

Position in the periodic table

Open the interactive periodic table →

Data compiled from Wikipedia, PubChem, and IUPAC. Source.