Element 98
Californium
Actinides
Californium (Cf) is in the f-block of the periodic table — group 3, period 7.
Californium is a radioactive metallic chemical element with symbol Cf and atomic number 98.
Key data
- Atomic number
- 98
- Atomic mass
- 251.000 u
- Group / Period
- 3 / 7
- Block
- f-block
- Phase at STP
- Solid
- Density
- 15.1 g/cm³
- Melting point
- 899.9 °C
- Boiling point
- 1469.8 °C
- Electron configuration
- [Rn] 5f10 7s2
Periodic table block
Californium is in the f-block (group 3, period 7). 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
- •Neutron sources for cancer therapy
- •Oil-well logging
- •Research only
Discovery
Year: 1950
Discovered by: Lawrence Berkeley National Laboratory
Frequently asked questions
What is the atomic number of Californium?
Californium has atomic number 98. Its symbol is Cf and its atomic mass is 251 u.
What category of element is Californium?
Californium is classified as actinides. It sits in group 3, period 7 of the periodic table.
What block of the periodic table is Californium in?
Californium is in the f-block (group 3, period 7). Its highest-energy electrons occupy the f subshell — you can see this in its electron configuration, [Rn] 5f10 7s2.
What is Californium used for?
Common uses of Californium include: Neutron sources for cancer therapy, Oil-well logging, Research only.
When was Californium discovered?
Californium was discovered in 1950 by Lawrence Berkeley National Laboratory.
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