All practice pages/Interatomic theory/Elements
Element 102, an actinide
Named for Alfred Nobel, after a dispute over its discovery that took decades to settle.
Period 7, in the actinide row set below the main table. The other actinides are tinted, and every cell opens its own article.
Nobelium has 102 electrons, one for every proton, so the atom carries no charge. Below are the same 102 electrons written two ways.
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 7s²
Short form: [Rn] 5f¹⁴ 7s², where [Rn] stands for the 86 electrons radon already has.
That list runs by shell. In the order the subshells fill it reads [Rn] 7s² 5f¹⁴, because a subshell fills by its energy, not by its shell number.
The simple form counts electrons shell by shell. The orbital form says which subshell each one sits in: s holds 2, p holds 6, d holds 10 and f holds 14. Shell 4 here is 4s² 4p⁶ 4d¹⁰ 4f¹⁴, and 2 + 6 + 10 + 14 is 32.
Nobelium sits in period 7 and has 7 shells. The period number counts the shells.
The outer shell holds 2 electrons. Those are the ones nobelium can lose, gain or share, so they are the ones that decide what it bonds with.
Unlike most actinides, nobelium is most stable as No²⁺, because that ion keeps a completely filled set of fourteen 5f electrons.
Not found in nature; made a few atoms at a time in particle accelerators.
A team at the Nobel Institute in Stockholm claimed it in 1957 and proposed the name nobelium, but the result could not be repeated. Work at Berkeley in 1958 and at Dubna in the Soviet Union in the 1960s followed. Credit eventually went to the Dubna team, but the name nobelium stayed.
Research only.
Radioactive; it has only ever existed a few atoms at a time.