69
Tm
168.93
Thulium (Tm)
Element 69 · Period 6 · Lanthanide series
lanthanide
solid at room temp
f-block
About Thulium
Rarest stable lanthanoid. Used in portable X-ray devices and surgical lasers.
Physical Properties
Atomic Mass
168.93 u
State at 25°C
Solid
Melting Point
1545 °C
Boiling Point
1950 °C
Density
9.32 g/cm³
Magnetism
Paramagnetic
Atomic Properties
Electron Configuration
[Xe] 4f¹³ 6s²
Electron Shells
2, 8, 18, 31, 8, 2
Electronegativity
1.25
Atomic Radius
222 pm
Ionization Energy
597 kJ/mol
Oxidation States
+3
Discovery & History
Discovered By
Per Teodor Cleve
Discovery Year
1879
Named By
Per Teodor Cleve
Name origin: Thule (ancient name for Scandinavia)
Frequently Asked Questions
- Is Thulium a metal, nonmetal, or metalloid?
- Thulium is classified as a lanthanide.
- What state is Thulium in at room temperature?
- Thulium is a solid at standard room temperature (25°C).
- What is the atomic mass of Thulium?
- Thulium has an atomic mass of 168.93 atomic mass units (u).
- Who discovered Thulium?
- Thulium was discovered by Per Teodor Cleve in 1879.
- Where is Thulium on the periodic table?
- Thulium is element number 69, located in period 6, part of the lanthanide series shown below the main table.