Basic Information
Bohr Model
Static
Interactive
Descriptive Numbers
CAS Number
7440-11-1
Mendeleev Number
38
Pettifor Number
36
Glawe Number
45
Mass
Atomic Mass
258 Da
Periodic Position
X Position
16
Y Position
9
Period
7
Group
N/A
Classification
Block
f
Category
Actinides
Goldschmidt
Synthetic
Color
Jmol
#B30DA6
Molcas Gv
#B30DA6
CPK
#FFFFFF
Atomic Radius
Uff
327.4
Covalent (Pyykko)
173
Covalent (Pyykko Double)
139
Temperature
Melting/Freeze (USE)
1100 °K
Melting/Freeze (WEL)
1100 °K
Melting/Freeze (CRC)
1100 °K
Heat
Adiabatic Index
N/A
Etymology
Description
It is a transuranic and radioactive metal element. It is in the actinide series. Its only known isotope, Md-256, has a half-life of 1.3 hours. It was first discovered by Glen T. Seaborg, Albert Ghiorso and colleagues in 1955. The name Unnilunium has been suggested as an alternative. It is named after Dmitri Mendeleyev, the "inventor" of the periodic table.
Origin Of Word
Chemist and inventor Dmitry Mendeleev
Symbol Origin
surname, eponym
Etymological Description
This name was given in honor of Dmitry Mendeleev, who invented the periodic table. It is also called ekathulium.
Discovery & Isolation
Observed/Predicted By
A. Ghiorso, G. Harvey, R. Choppin, S. G. Thompson and G. T. Seaborg (Berkeley Radiation Laboratory)
Observed/Discovery Year
1955
Isolated Sample By
Lawrence Berkeley National Laboratory
Production & Use
Sources
It is obtained by bombarding einchenium with helium ions.
Uses
It has no significant commercial use.
Radioactivity
Half Life
51.5 days
Lifetime
74.31 days
Decay Mode
Alpha Six
Electron Affinity
Electron Affinity (kJ/mol)
93.91
Electron Affinity (pauling)
1.3
Electron Affinity (ghosh)
0.23542
Dipole Polarity
Accepted
109
Uncertainty
20
Electron & Quantum
Oxidation States
2,3
Electron Configuration
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f13
Quantum Number
Fah/A
Electron Configuration Semantic
[Rn] 5f13 7s2
Shells-0
2
Shells-1
8
Shells-2
18
Shells-3
32
Shells-4
31
Shells-5
8
Shells-6
2
Ionization Energies-0
635
