Is mendelevium a metal?

Yes. Mendelevium is a metal, classified as an actinide on the periodic table.

How many protons does mendelevium have?

Mendelevium has 101 protons. Its atomic number is 101, which is also the number of electrons in a neutral atom of mendelevium.

What group and period is mendelevium in?

Mendelevium is in period 7 of the periodic table. As an actinide in the f-block, it sits in a separate row below the main table and has no standard group number.

What is the atomic mass of mendelevium?

The atomic mass of mendelevium is 258 u (unified atomic mass units).

Element 101

Mendelevium (Md)

Actinide · Period 7 · f-block

Mendelevium (Md) is element 101 of the periodic table, an actinide in period 7 (f-block) with an atomic mass of 258 and is a solid at standard conditions.

At a glance

Atomic number: 101
Symbol: Md
Atomic mass: 258 u
Category: Actinides
Period: 7
Block: f-block
Phase at STP: solid

Electron structure

Electron configuration: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 5f13 7s2
Shorthand configuration: [Rn] 5f13 7s2
Electrons per shell: 2, 8, 18, 32, 31, 8, 2
Oxidation states: +2, +3

Physical properties

Mendelevium has only ever been produced in quantities too small to weigh or observe in bulk. The physical and atomic values below are theoretical predictions from periodic trends and relativistic calculations, not measurements.

Melting point: 1,100 K (826.85 °C) (predicted)
Density: 10.3 g/cm³ (predicted)
Phase: solid

Atomic properties

Electronegativity (Pauling): 1.3 (predicted)
First ionization energy: 635 kJ/mol (predicted)
Electron affinity: 94 kJ/mol (predicted)

Notable isotopes

Notable isotopes of Mendelevium: mass number, atomic mass, natural abundance, and stability.
Isotope	Mass	Abundance	Stability
Md-258	258.09843	-	Half-life 51.5 days

Common uses

Scientific research only

Discovery

Year: 1955
Discovered by: Albert Ghiorso, Glenn T. Seaborg
Country: USA

Frequently asked questions

Is mendelevium a metal?: Yes. Mendelevium is a metal, classified as an actinide on the periodic table.
How many protons does mendelevium have?: Mendelevium has 101 protons. Its atomic number is 101, which is also the number of electrons in a neutral atom of mendelevium.
What group and period is mendelevium in?: Mendelevium is in period 7 of the periodic table. As an actinide in the f-block, it sits in a separate row below the main table and has no standard group number.
What is the atomic mass of mendelevium?: The atomic mass of mendelevium is 258 u (unified atomic mass units).

Keep exploring

Mendelevium's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.