Berkelium (Bk)
Actinide · f-block · period 7
Silvery radioactive metal (only microgram amounts have ever been made).
Berkelium (symbol Bk) is chemical element number 97, a actinide in the actinide series (f-block), period 7 of the periodic table. Its standard atomic weight is (247) and its electron configuration is [Rn] 5f9 7s2. At room temperature it is a solid, and it is radioactive. Named after Berkeley, California, where it and many other heavy elements were made.
Properties
| Atomic number | 97 |
|---|---|
| Atomic mass | (247) |
| Category | Actinide |
| Block | f-block |
| Group · Period | f-block series · 7 |
| Electron configuration | [Rn] 5f9 7s2 |
| Electrons per shell | 2, 8, 18, 32, 27, 8, 2 |
| State at 25 °C | solid |
| Melting point | 1259 K |
| Boiling point | 2900 K |
| Density | 14.78 g/cm³ |
| Electronegativity (Pauling) | 1.3 |
| Radioactive | Yes — no stable isotope |
| Origin | synthetic |
| Discovered | 1949 · Thompson, Ghiorso & Seaborg |
Key facts about Berkelium
- Named after Berkeley, California, where it and many other heavy elements were made.
- A few milligrams of berkelium-249 were the target used to make element 117, tennessine.
- Producing that target took about 250 days of reactor irradiation and 90 days of processing.
- One of the rarest substances ever handled by chemists.
What Berkelium is used for
Target material for synthesising still-heavier elements; basic research only.
Where it sits in the periodic table
Berkelium is in the actinide series, period 7, of the f-block. Its electron configuration [Rn] 5f9 7s2 means its outermost shell holds 2 electrons, which is what places it here and explains much of its chemistry. See Berkelium on the interactive table →
Berkelium — frequently asked questions
What is Berkelium used for?
Target material for synthesising still-heavier elements; basic research only.
Is Berkelium radioactive?
Yes. Berkelium has no stable isotope, so every form of it is radioactive.
What is the electron configuration of Berkelium?
Berkelium has the electron configuration [Rn] 5f9 7s2, which is 2, 8, 18, 32, 27, 8, 2 electrons per shell.
What group and period is Berkelium in?
Berkelium is in the actinide series (f-block), period 7, in the f-block. Its outer shell holds 2 electrons.
Who discovered Berkelium?
Berkelium was discovered in 1949 by Thompson, Ghiorso & Seaborg.