Nobelium (No)
Actinide · f-block · period 7
Never seen in bulk.
Nobelium (symbol No) is chemical element number 102, a actinide in the actinide series (f-block), period 7 of the periodic table. Its standard atomic weight is (259) and its electron configuration is [Rn] 5f14 7s2. Its state at room temperature is unknown, and it is radioactive. Named after Alfred Nobel.
Properties
| Atomic number | 102 |
|---|---|
| Atomic mass | (259) |
| Category | Actinide |
| Block | f-block |
| Group · Period | f-block series · 7 |
| Electron configuration | [Rn] 5f14 7s2 |
| Electrons per shell | 2, 8, 18, 32, 32, 8, 2 |
| State at 25 °C | unknown |
| Melting point | 1100 K |
| Boiling point | — |
| Density | — |
| Electronegativity (Pauling) | 1.3 |
| Radioactive | Yes — no stable isotope |
| Origin | synthetic |
| Discovered | 1966 · Flerov et al. (Dubna) |
Key facts about Nobelium
- Named after Alfred Nobel.
- Unusually, its most stable ion in solution is the +2 state, not the +3 typical of actinides.
- American and Soviet labs disputed who discovered it all through the Cold War.
- Only a few atoms have ever existed at once.
What Nobelium is used for
None — research only.
Where it sits in the periodic table
Nobelium is in the actinide series, period 7, of the f-block. Its electron configuration [Rn] 5f14 7s2 means its outermost shell holds 2 electrons, which is what places it here and explains much of its chemistry. See Nobelium on the interactive table →
Nobelium — frequently asked questions
What is Nobelium used for?
None — research only.
Is Nobelium radioactive?
Yes. Nobelium has no stable isotope, so every form of it is radioactive.
What is the electron configuration of Nobelium?
Nobelium has the electron configuration [Rn] 5f14 7s2, which is 2, 8, 18, 32, 32, 8, 2 electrons per shell.
What group and period is Nobelium in?
Nobelium is in the actinide series (f-block), period 7, in the f-block. Its outer shell holds 2 electrons.
Who discovered Nobelium?
Nobelium was discovered in 1966 by Flerov et al. (Dubna).