Fermium

Fermium (Fm)

Fermium is the 100th element in the periodic table and has a symbol of Fm and atomic number of 100. It has an atomic weight of (257) and a mass number of 241. Fermium has one hundred protons and one hundred forty-one neutrons in its nucleus, and one hundred electrons in seven shells. It is located in group Actinides, period seven and block f of the periodic table. Radioactive metallic transuranic element, belongs to the actinoids. Ten known isotopes, most stable is Fm-257 with a half-life of 10 days. First identified by Albert Ghiorso and associates in the debris of the first hydrogen-bomb explosion in 1952.
Atomic Number100
Atomic Weight257
Mass Number241
Group
Period7
Blockf
Protons100 p+
Neutrons141 n0
Electrons100 e-
Animated Bohr Model of Fm (Fermium)

Physical Properties

Atomic Radius
Molar Volume
Covalent Radius
167 pm
Metallic Radius
Ionic Radius
110.5 pm
Crystal Radius
124.5 pm
Van der Waals Radius
245 pm
Density
9.7 g/cm³

Chemical Properties

Energy
Proton Affinity
Electron Affinity
Ionization Energy
Ionization Energies of Fm (Fermium)
Heat of Vaporization
Heat of Fusion
Heat of Formation
Electrons
Electron Shells2, 8, 18, 32, 30, 8, 2
Bohr Model: Fm (Fermium)
Valence Electrons2
Lewis Structure: Fm (Fermium)
Electron Configuration[Rn] 5f12 7s2
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 5f12 7s2
Enhanced Bohr Model of Fm (Fermium)
Orbital Diagram of Fm (Fermium)
Oxidation States2, 3
Electronegativity
Electrophilicity Index
States of Matter
PhaseSolid
Gas Phase
Boiling Point
Melting Point
1,800.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual

Fermium is a Colorless. Fm has a CPK of #ffffff, Jmol of #b31fba, and MOLCAS GV of #b31fba.

Color
Colorless
Appearance
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
Molar Heat Capacity
Specific Heat Capacity
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type
Electrical Conductivity
Electrical Resistivity
Superconducting Point
Magnetism
Type
Magnetic Susceptibility (Mass)
Magnetic Susceptibility (Molar)
Magnetic Susceptibility (Volume)
Magnetic Ordering
Curie Point
Neel Point
Structure

The lattice angles of Fermium is .

Crystal Structure ()
Lattice Constant
Lattice Angles
Mechanical Properties
Hardness
Bulk Modulus
Shear Modulus
Young's Modulus
Poisson Ratio
Speed of Sound
Classification

The Glawe Number of Fermium is 44. The Mendeleev Number of Fm is 36. The Pettifor Number of Element 100 is 37. The Goldschmidt Class of Fermium (Fm) is synthetic.

CategoryActinides, Actinides
CAS Group
IUPAC Group
Glawe Number44
Mendeleev Number36
Pettifor Number37
Geochemical Class
Goldschmidt Classsynthetic

Other

The Dipole Polarizability of Fermium is 113 plus or minus 20 a₀. The Allotropes of Fm is . The Neutron Cross Section of Element 100 is 5800. The Quantum Numbers of Fermium (Fm) is 3H6. The Space Group of Fermium is ().

Gas Basicity
Dipole Polarizability
113 ± 20 a₀
C6 Dispersion Coefficient
Allotropes
Neutron Cross Section
5,800
Neutron Mass Absorption
Quantum Numbers3H6
Space Group ()

Isotopes of Fermium

Stable Isotopes0
Unstable Isotopes20
Natural Isotopes0

241Fm

Mass Number241
Neutron Number141
Relative Atomic Mass
241.074311 ± 0.000322 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
730 ± 60 us
Spin5/2
Quadrupole Moment
Discovery Year2008
Parity+

Decay ModeIntensity
SF (spontaneous fission)
α (α emission)14%
β+ (β+ decay; β+ = ϵ + e+)12%

242Fm

Mass Number242
Neutron Number142
Relative Atomic Mass
242.07343 ± 0.00043 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
800 ± 200 us
Spin0
Quadrupole Moment
0
Discovery Year1975
Parity+

Decay ModeIntensity
SF (spontaneous fission)100%
α (α emission)

243Fm

Mass Number243
Neutron Number143
Relative Atomic Mass
243.074414 ± 0.00014 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
231 ± 9 ms
Spin7/2
Quadrupole Moment
Discovery Year1981
Parity-

Decay ModeIntensity
α (α emission)91%
SF (spontaneous fission)9%
β+ (β+ decay; β+ = ϵ + e+)

244Fm

Mass Number244
Neutron Number144
Relative Atomic Mass
244.074036 ± 0.000216 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
3.12 ± 0.08 ms
Spin0
Quadrupole Moment
0
Discovery Year1967
Parity+

Decay ModeIntensity
SF (spontaneous fission)97%
β+ (β+ decay; β+ = ϵ + e+)2%
α (α emission)1%

245Fm

Mass Number245
Neutron Number145
Relative Atomic Mass
245.075354 ± 0.00021 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
4.2 ± 1.3 s
Spin1/2
Quadrupole Moment
0
Discovery Year1967
Parity+

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)7%
SF (spontaneous fission)0.3%

246Fm

Mass Number246
Neutron Number146
Relative Atomic Mass
246.075353334 ± 0.000014675 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
1.54 ± 0.04 s
Spin0
Quadrupole Moment
0
Discovery Year1966
Parity+

Decay ModeIntensity
α (α emission)93.2%
SF (spontaneous fission)6.8%
ϵ (electron capture)1.3%

247Fm

Mass Number247
Neutron Number147
Relative Atomic Mass
247.076944 ± 0.000194 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
31 ± 1 s
Spin7/2
Quadrupole Moment
Discovery Year1967
Parity+

Decay ModeIntensity
α (α emission)64%
β+ (β+ decay; β+ = ϵ + e+)

248Fm

Mass Number248
Neutron Number148
Relative Atomic Mass
248.077185451 ± 0.000009122 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
34.5 ± 1.2 s
Spin0
Quadrupole Moment
0
Discovery Year1958
Parity+

Decay ModeIntensity
α (α emission)100%
β+ (β+ decay; β+ = ϵ + e+)
SF (spontaneous fission)0.1%

249Fm

Mass Number249
Neutron Number149
Relative Atomic Mass
249.078926042 ± 0.000006668 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
1.6 ± 0.1 m
Spin7/2
Quadrupole Moment
Discovery Year1960
Parity+

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)
α (α emission)33%

250Fm

Mass Number250
Neutron Number150
Relative Atomic Mass
250.079519765 ± 0.000008468 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
31 ± 1.1 m
Spin0
Quadrupole Moment
0
Discovery Year1954
Parity+

Decay ModeIntensity
α (α emission)100%
SF (spontaneous fission)0.0069%
ϵ (electron capture)

251Fm

Mass Number251
Neutron Number151
Relative Atomic Mass
251.08154513 ± 0.000015342 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
5.3 ± 0.08 h
Spin9/2
Quadrupole Moment
Discovery Year1957
Parity-

Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)98.2%
α (α emission)1.8%

252Fm

Mass Number252
Neutron Number152
Relative Atomic Mass
252.082466019 ± 0.000005604 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
25.39 ± 0.04 h
Spin0
Quadrupole Moment
0
Discovery Year1956
Parity+

Decay ModeIntensity
α (α emission)100%
SF (spontaneous fission)0.0023%
+ (double β+ decay)

253Fm

Mass Number253
Neutron Number153
Relative Atomic Mass
253.085180945 ± 0.000001662 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
3 ± 0.12 d
Spin1/2
Quadrupole Moment
0
Discovery Year1957
Parity+

Decay ModeIntensity
ϵ (electron capture)88%
α (α emission)12%

254Fm

Mass Number254
Neutron Number154
Relative Atomic Mass
254.086852424 ± 0.000001978 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
3.24 ± 0.002 h
Spin0
Quadrupole Moment
0
Discovery Year1954
Parity+

Decay ModeIntensity
α (α emission)99.9408%
SF (spontaneous fission)0.0592%

255Fm

Mass Number255
Neutron Number155
Relative Atomic Mass
255.089963495 ± 0.000004223 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
20.07 ± 0.07 h
Spin7/2
Quadrupole Moment
Discovery Year1954
Parity+

Decay ModeIntensity
α (α emission)100%
SF (spontaneous fission)2.4%

256Fm

Mass Number256
Neutron Number156
Relative Atomic Mass
256.091771699 ± 0.000003241 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
157.1 ± 1.3 m
Spin0
Quadrupole Moment
0
Discovery Year1955
Parity+

Decay ModeIntensity
SF (spontaneous fission)91.9%
α (α emission)8.1%

257Fm

Mass Number257
Neutron Number157
Relative Atomic Mass
257.095105419 ± 0.000004669 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
100.5 ± 0.2 d
Spin9/2
Quadrupole Moment
Discovery Year1964
Parity+

Decay ModeIntensity
α (α emission)99.79%
SF (spontaneous fission)0.21%

258Fm

Mass Number258
Neutron Number158
Relative Atomic Mass
258.097077 ± 0.000215 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
370 ± 14 us
Spin0
Quadrupole Moment
0
Discovery Year1971
Parity+

Decay ModeIntensity
SF (spontaneous fission)100%
α (α emission)

259Fm

Mass Number259
Neutron Number159
Relative Atomic Mass
259.100596 ± 0.000304 Da
G-Factor
Abundance
Radioactivity☢️ Radioactive
Half Life
1.5 ± 0.2 s
Spin
Quadrupole Moment
Discovery Year1980
Parity

Decay ModeIntensity
SF (spontaneous fission)100%

260Fm

Mass Number260
Neutron Number160
Relative Atomic Mass
260.102809 ± 0.000467 Da
G-Factor
0
Abundance
Radioactivity☢️ Radioactive
Half Life
Spin0
Quadrupole Moment
0
Discovery Year
Parity+

Decay ModeIntensity
SF (spontaneous fission)
Fermium-Ytterbium Alloy
Electron shell 100 Fermium

History

Fermium was discovered as a component of the debris of the first hydrogen bomb explosion in 1952. It was identified by Albert Ghiorso and co-workers at the University of California, Berkeley in collaboration with the Argonne and Los Alamos National Laboratories, in the fallout from the Ivy Mike nuclear test. The new element was produced by the nuclear fission of 17 neutrons with uranium-238. Named after Nobel laureate Enrico Fermi, one of the pioneers of nuclear physics

DiscoverersArgonne, Los Alamos, U of Calif
Discovery LocationUnited States
Discovery Year1953
Etymology (Name Origin)Named in honor of the scientist Enrico Fermi.
PronunciationFER-mi-em (English)
Fermium is harmful due to its radioactivity
Sixteen isotopes of fermium are known to exist

Uses

Fermium is used for scientific research purposes only. It has no significant commercial applications.

Sources

Produced by bombarding lighter transuranium elements with still lighter particles or by neutron capture.

Abundance
Abundance in Earth's crust
Natural Abundance (Oceans)
Natural Abundance (Human Body)
0 %
Natural Abundance (Meteor)
0 %
Natural Abundance (Sun)
0 %
Abundance in Universe
0 %

Nuclear Screening Constants

Also Known As

  • Fm
  • element 100
  • 100Fm

Translations

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