101 predicted 2 · 8 · 18 · 32 · 31 · 8 · 2

Mendelevium, Md, element 101

Actinide· Period 7· f-block

Configuration [Rn]5f137s2

Atomic weight
258Da
Phase
solid, predicted
Density
10.3g/cm³, predicted
Melting point
1,100.15K, predicted 827 °C
Boiling point
No data
Electronegativity
1.3

Radioactive metallic transuranic element. Belongs to the actinoid series. Only known isotope, Md-256 has a half-life of 1.3 hours. First identified by Glenn T. Seaborg, Albert Ghiorso and associates in 1955. Alternative name Unnilunium has been proposed. Named after the 'inventor' of the periodic table, Dmitri Mendeleev. Description from mendeleev.

Back to the table
The outermost shell: the valence electronsThe inner shellsThe nucleus One bead for each electron, on the ring of its shell, counted from the nucleus out. The rings turn at their own pace; the model is Bohr's picture of the atom, which places electrons in shells but not on true orbits.

Atomic properties

4 of 5 fields have a value for mendelevium

Atomic weight The standard atomic weight. For an element with no stable isotope, the mass of its longest-lived isotope.
258Da
Source: mendeleev
Electron configuration
[Rn]5f137s2
Source: mendeleev
Electron configuration in full The electron configuration with the noble-gas core written out.
1s22s22p63s23p63d104s24p64d104f145s25p65d105f136s26p67s2
Source: Worked outfrom electron configuration
Electrons in each shell Counted from the electron configuration, from the first shell outward.
2 · 8 · 18 · 32 · 31 · 8 · 2
Source: Worked outfrom electron configuration

No data uncertainty of the atomic weight.