Basic Information
Bohr Model
Static
Interactive
Descriptive Numbers
CAS Number
7440-72-4
Mendeleev Number
36
Pettifor Number
37
Glawe Number
44
Mass
Atomic Mass
257 Da
Periodic Position
X Position
15
Y Position
9
Period
7
Group
N/A
Classification
Block
f
Category
Actinides
Goldschmidt
Synthetic
Color
Jmol
#B31FBA
Molcas Gv
#B31FBA
CPK
#FFFFFF
Atomic Radius
Uff
328.6
Covalent (Pyykko)
167
Temperature
Melting/Freeze (USE)
1800 °K
Melting/Freeze (WEL)
1800 °K
Melting/Freeze (CRC)
1800 °K
Melting/Freeze (LNG)
1800 °K
Heat
Adiabatic Index
N/A
Etymology
Description
It is a transuranic and radioactive metal element. It is a member of the actinides class. There are ten known isotopes. Fm-257, with a half-life of 10 days, is the most stable. It was found in the debris of the first hydrogen bomb detonated by Albert Ghiorso and his colleagues in 1952.
Language Of Origin
Italian
Origin Of Word
From physicist Enrico Fermi
Meaning
Italian surname. "Buckle" is from the combination of ferm- and -i meaning "snap".
Symbol Origin
surname, eponym
Etymological Description
This name was given in honor of Enrico Fermi, who developed the first nuclear reactor, quantum theory, nuclear and particle physics, and statistical mechanics.
Discovery & Isolation
Observed/Predicted By
A. Ghiorso et al. (Argonne Laboratory, Los Alamos Laboratory and University of California, Berkeley)
Observed/Discovery Year
1952
Isolated Sample By
Lawrence Berkeley National Laboratory
Production & Use
Sources
It is obtained by bombarding lighter transuranium elements with lighter particles or by neutron capture.
Uses
It has no significant commercial use.
Radioactivity
Half Life
100.5 days
Lifetime
145.02 days
Decay Mode
Alpha Six
Neutron Cross Section
5.8×103
Electron Affinity
Electron Affinity (kJ/mol)
33.96
Electron Affinity (pauling)
1.3
Electron Affinity (ghosh)
0.22485
Dipole Polarity
Accepted
113
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 5f12
Quantum Number
Ahht
Electron Configuration Semantic
[Rn] 5f12 7s2
Shells-0
2
Shells-1
8
Shells-2
18
Shells-3
32
Shells-4
30
Shells-5
8
Shells-6
2
Ionization Energies-0
627
