← Periodic Table
69
f🧱
Tm
168.9300

Thulium

Lanthanide

Atomic Properties

Atomic Number
69
Atomic Mass
168.9300 u
Electron Configuration
[Xe] 4f13 6s2
Electronegativity
1.25
Block
f-block
Group
Period
6

🌡 Physical Properties

Phase (STP)
solid
Melting Point
1818.00 K
Boiling Point
2223.00 K
Density
9.3200 g/cm³

About Thulium

Rarest lanthanide; used in portable X-ray machines and lasers.

🔬 Isotopes of Thulium

Thulium has 1 naturally occurring isotope.

IsotopeMass NumberAtomic Mass (u)AbundanceType
169Tm169168.9342179100.00%Stable

Data source: NIH PubChem (aggregated from IUPAC, NIST)