Element 65
Terbium
Lanthanides
Terbium (Tb) is in the f-block of the periodic table — group 3, period 6.
Terbium is a chemical element with symbol Tb and atomic number 65.
Key data
- Atomic number
- 65
- Atomic mass
- 158.925 u
- Group / Period
- 3 / 6
- Block
- f-block
- Phase at STP
- Solid
- Density
- 8.23 g/cm³
- Melting point
- 1355.8 °C
- Boiling point
- 3122.8 °C
- Electron configuration
- [Xe] 4f9 6s2
Periodic table block
Terbium is in the f-block (group 3, period 6). Elements land in the f-block when their highest-energy electrons fill an f subshell — these are the lanthanides and actinides shown beneath the main table.
New to this? Periodic table blocks explained: s, p, d, and f
Common uses
- •Green phosphors
- •Solid-state devices
- •Low-energy bulbs
Discovery
Year: 1843
Discovered by: Carl Gustaf Mosander
Frequently asked questions
What is the atomic number of Terbium?
Terbium has atomic number 65. Its symbol is Tb and its atomic mass is 158.925 u.
What category of element is Terbium?
Terbium is classified as lanthanides. It sits in group 3, period 6 of the periodic table.
What block of the periodic table is Terbium in?
Terbium is in the f-block (group 3, period 6). Its highest-energy electrons occupy the f subshell — you can see this in its electron configuration, [Xe] 4f9 6s2.
What is Terbium used for?
Common uses of Terbium include: Green phosphors, Solid-state devices, Low-energy bulbs.
When was Terbium discovered?
Terbium was discovered in 1843 by Carl Gustaf Mosander.
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