Nobelium (No)

Nobelium properties

Atomic number

102

Atomic mass

259 u

Category

Actinide

Group

—

Period

7

Block

f-block

State at room temp.

Solid

Electronegativity

1.3

Melting point

1,100 K (826.8 °C)

Boiling point

—

Density

—

Valence electrons

2

Common charges

+2, +3

Oxidation states

+3, +2

Atomic radius

—

Ionization energy

6.65 eV

Electron affinity

—

Radioactive

Yes, no stable isotopes

Discovered

1958

Nobelium electron configuration

The electron configuration of Nobelium (No) is [Rn] 5f14 7s2. Its 102 electrons are arranged in shells as 2, 8, 18, 32, 32, 8, 2.

Protons, neutrons and electrons in Nobelium

A neutral Nobelium atom has 102 protons and 102 electrons. Most Nobelium atoms have about 157 neutrons: the atomic mass rounded to 259, minus the atomic number 102.

Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass

How many valence electrons does Nobelium have?

2

Nobelium has 2 valence electrons in its outermost shell. As an f-block element, its 4f or 5f electrons can also take part in bonding.

See every element: Periodic table with valence electrons

Nobelium orbital diagram

Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations

Molar mass of Nobelium

259 g/mol

One mole of Nobelium atoms (6.022 × 10²³ atoms) has a mass of 259 grams. Use this value to convert between grams and moles.

Nobelium facts

• Nobelium's 14 electrons in the 5f subshell fill it completely, mirroring ytterbium directly above it in the lanthanide row.
• Its longest-lived isotope, nobelium-259, has a half-life of about 58 minutes.
• Nobelium (No) has atomic number 102 and is a solid at room temperature. It was discovered in 1958.

Position in the periodic table

Nobelium is element 102, in period 7 of the periodic table. It is one of the Actinides in the f-block, shown in the rows below the main table.

All actinides

Uses of Nobelium

Nobelium has no uses outside research because only a few atoms can be made at a time in particle accelerators. Chemists study it because, unlike most other actinides, it is most stable as a +2 ion in water rather than +3. Experiments with single atoms help test how electron structure shapes the chemistry of the heaviest elements.

Who discovered Nobelium?

A team working at the Nobel Institute of Physics in Stockholm claimed nobelium in 1957 but could not be confirmed; Albert Ghiorso's team at Berkeley reported it in 1958, and work at Dubna in the Soviet Union in the 1960s firmly established its properties. The name honors Alfred Nobel.

Where does the name come from?

Nobelium honors Alfred Nobel, the Swedish chemist who invented dynamite and founded the Nobel Prizes. The name was proposed in 1957 by a team at the Nobel Institute of Physics in Stockholm, though their discovery claim was not confirmed.

Discovery timeline