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 Number	100
Atomic Weight	257
Mass Number	241

Group
Period	7
Block	f

Protons	100 p⁺
Neutrons	141 n⁰
Electrons	100 e^-

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 328.6 pm
Density	9.7 g/cm³

Chemical Properties

Energy

Proton Affinity
Electron Affinity
Ionization Energy	6.5 eV/particle 10 eV/particle 23.2 eV/particle 39.3 eV/particle 55 eV/particle 74 eV/particle 93 eV/particle 120 eV/particle 136 eV/particle 162 eV/particle 185 eV/particle 209 eV/particle 237 eV/particle 257 eV/particle 276 eV/particle 300 eV/particle 326 eV/particle 351 eV/particle 377 eV/particle 402 eV/particle 430 eV/particle 453 eV/particle 616 eV/particle 647 eV/particle 680 eV/particle 716 eV/particle 749 eV/particle 782 eV/particle 837 eV/particle 871 eV/particle 909 eV/particle 944 eV/particle 1,110 eV/particle 1,150 eV/particle 1,190 eV/particle 1,230 eV/particle 1,370 eV/particle 1,420 eV/particle 1,550 eV/particle 1,600 eV/particle 1,770 eV/particle 1,860 eV/particle 1,940 eV/particle 2,030 eV/particle 2,120 eV/particle 2,210 eV/particle 2,300 eV/particle 2,390 eV/particle 2,490 eV/particle 2,590 eV/particle 2,680 eV/particle 2,760 eV/particle 2,900 eV/particle 2,950 eV/particle 3,403 eV/particle 3,480 eV/particle 3,561 eV/particle 3,647 eV/particle 3,730 eV/particle 3,810 eV/particle 3,986 eV/particle 4,070 eV/particle 4,160 eV/particle 4,245 eV/particle 4,586 eV/particle 4,670 eV/particle 4,760 eV/particle 4,840 eV/particle 5,420 eV/particle 5,510 eV/particle 5,760 eV/particle 5,860 eV/particle 9,200 eV/particle 9,370 eV/particle 9,570 eV/particle 9,770 eV/particle 9,970 eV/particle 10,160 eV/particle 10,660 eV/particle 10,860 eV/particle 11,080 eV/particle 11,280 eV/particle 11,850 eV/particle 12,020 eV/particle 12,220 eV/particle 12,390 eV/particle 14,180 eV/particle 14,400 eV/particle 14,800 eV/particle 15,000 eV/particle 30,300 eV/particle 30,800 eV/particle 31,300 eV/particle 31,800 eV/particle 38,400 eV/particle 39,100 eV/particle 40,000 eV/particle 40,482.2 eV/particle 158,152.5 eV/particle 160,804 eV/particle

Heat of Vaporization
Heat of Fusion
Heat of Formation
Electrons

Electron Shells	2, 8, 18, 32, 30, 8, 2

Valence Electrons	2 ⓘ

Electron Configuration	[Rn] 5f¹² 7s²ⓘ 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 5f¹² 7s²

Oxidation States	2, 3
Electronegativity	0.22485
Electrophilicity Index
States of Matter

Phase	Solid
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 #ffffff #b31fba #b31fba
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.
Category	Actinides, Actinides
CAS Group
IUPAC Group
Glawe Number	44
Mendeleev Number	36
Pettifor Number	37
Geochemical Class
Goldschmidt Class	synthetic

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 Numbers	3H6
Space Group	()

Isotopes of Fermium

Stable Isotopes	0
Unstable Isotopes	20
Natural Isotopes	0

²⁴¹Fm

Mass Number	241
Neutron Number	141
Relative Atomic Mass	241.074311 ± 0.000322 Da
G-Factor
Abundance
Radioactivity	☢️ Radioactive
Half Life	730 ± 60 us
Spin	5/2
Quadrupole Moment
Discovery Year	2008
Parity	+

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

²⁴²Fm

Mass Number	242
Neutron Number	142
Relative Atomic Mass	242.07343 ± 0.00043 Da
G-Factor	0
Abundance
Radioactivity	☢️ Radioactive
Half Life	800 ± 200 us
Spin	0
Quadrupole Moment	0
Discovery Year	1975
Parity	+

Decay Mode	Intensity
SF (spontaneous fission)	100%
α (α emission)

²⁴³Fm

Mass Number	243
Neutron Number	143
Relative Atomic Mass	243.074414 ± 0.00014 Da
G-Factor
Abundance
Radioactivity	☢️ Radioactive
Half Life	231 ± 9 ms
Spin	7/2
Quadrupole Moment
Discovery Year	1981
Parity	-

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

²⁴⁴Fm

Mass Number	244
Neutron Number	144
Relative Atomic Mass	244.074036 ± 0.000216 Da
G-Factor	0
Abundance
Radioactivity	☢️ Radioactive
Half Life	3.12 ± 0.08 ms
Spin	0
Quadrupole Moment	0
Discovery Year	1967
Parity	+

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

²⁴⁵Fm

Mass Number	245
Neutron Number	145
Relative Atomic Mass	245.075354 ± 0.00021 Da
G-Factor
Abundance
Radioactivity	☢️ Radioactive
Half Life	4.2 ± 1.3 s
Spin	1/2
Quadrupole Moment	0
Discovery Year	1967
Parity	+

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

²⁴⁶Fm

Mass Number	246
Neutron Number	146
Relative Atomic Mass	246.075353334 ± 0.000014675 Da
G-Factor	0
Abundance
Radioactivity	☢️ Radioactive
Half Life	1.54 ± 0.04 s
Spin	0
Quadrupole Moment	0
Discovery Year	1966
Parity	+

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

²⁴⁷Fm

Mass Number	247
Neutron Number	147
Relative Atomic Mass	247.076944 ± 0.000194 Da
G-Factor
Abundance
Radioactivity	☢️ Radioactive
Half Life	31 ± 1 s
Spin	7/2
Quadrupole Moment
Discovery Year	1967
Parity	+

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

²⁴⁸Fm

Mass Number	248
Neutron Number	148
Relative Atomic Mass	248.077185451 ± 0.000009122 Da
G-Factor	0
Abundance
Radioactivity	☢️ Radioactive
Half Life	34.5 ± 1.2 s
Spin	0
Quadrupole Moment	0
Discovery Year	1958
Parity	+

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

²⁴⁹Fm

Mass Number	249
Neutron Number	149
Relative Atomic Mass	249.078926042 ± 0.000006668 Da
G-Factor
Abundance
Radioactivity	☢️ Radioactive
Half Life	1.6 ± 0.1 m
Spin	7/2
Quadrupole Moment
Discovery Year	1960
Parity	+

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

²⁵⁰Fm

Mass Number	250
Neutron Number	150
Relative Atomic Mass	250.079519765 ± 0.000008468 Da
G-Factor	0
Abundance
Radioactivity	☢️ Radioactive
Half Life	31 ± 1.1 m
Spin	0
Quadrupole Moment	0
Discovery Year	1954
Parity	+

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

²⁵¹Fm

Mass Number	251
Neutron Number	151
Relative Atomic Mass	251.08154513 ± 0.000015342 Da
G-Factor
Abundance
Radioactivity	☢️ Radioactive
Half Life	5.3 ± 0.08 h
Spin	9/2
Quadrupole Moment
Discovery Year	1957
Parity	-

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

²⁵²Fm

Mass Number	252
Neutron Number	152
Relative Atomic Mass	252.082466019 ± 0.000005604 Da
G-Factor	0
Abundance
Radioactivity	☢️ Radioactive
Half Life	25.39 ± 0.04 h
Spin	0
Quadrupole Moment	0
Discovery Year	1956
Parity	+

Decay Mode	Intensity
α (α emission)	100%
SF (spontaneous fission)	0.0023%
2β⁺ (double β⁺ decay)

²⁵³Fm

Mass Number	253
Neutron Number	153
Relative Atomic Mass	253.085180945 ± 0.000001662 Da
G-Factor
Abundance
Radioactivity	☢️ Radioactive
Half Life	3 ± 0.12 d
Spin	1/2
Quadrupole Moment	0
Discovery Year	1957
Parity	+

Decay Mode	Intensity
ϵ (electron capture)	88%
α (α emission)	12%

²⁵⁴Fm

Mass Number	254
Neutron Number	154
Relative Atomic Mass	254.086852424 ± 0.000001978 Da
G-Factor	0
Abundance
Radioactivity	☢️ Radioactive
Half Life	3.24 ± 0.002 h
Spin	0
Quadrupole Moment	0
Discovery Year	1954
Parity	+

Decay Mode	Intensity
α (α emission)	99.9408%
SF (spontaneous fission)	0.0592%

²⁵⁵Fm

Mass Number	255
Neutron Number	155
Relative Atomic Mass	255.089963495 ± 0.000004223 Da
G-Factor
Abundance
Radioactivity	☢️ Radioactive
Half Life	20.07 ± 0.07 h
Spin	7/2
Quadrupole Moment
Discovery Year	1954
Parity	+

Decay Mode	Intensity
α (α emission)	100%
SF (spontaneous fission)	2.4%

²⁵⁶Fm

Mass Number	256
Neutron Number	156
Relative Atomic Mass	256.091771699 ± 0.000003241 Da
G-Factor	0
Abundance
Radioactivity	☢️ Radioactive
Half Life	157.1 ± 1.3 m
Spin	0
Quadrupole Moment	0
Discovery Year	1955
Parity	+

Decay Mode	Intensity
SF (spontaneous fission)	91.9%
α (α emission)	8.1%

²⁵⁷Fm

Mass Number	257
Neutron Number	157
Relative Atomic Mass	257.095105419 ± 0.000004669 Da
G-Factor
Abundance
Radioactivity	☢️ Radioactive
Half Life	100.5 ± 0.2 d
Spin	9/2
Quadrupole Moment
Discovery Year	1964
Parity	+

Decay Mode	Intensity
α (α emission)	99.79%
SF (spontaneous fission)	0.21%

²⁵⁸Fm

Mass Number	258
Neutron Number	158
Relative Atomic Mass	258.097077 ± 0.000215 Da
G-Factor	0
Abundance
Radioactivity	☢️ Radioactive
Half Life	370 ± 14 us
Spin	0
Quadrupole Moment	0
Discovery Year	1971
Parity	+

Decay Mode	Intensity
SF (spontaneous fission)	100%
α (α emission)

²⁵⁹Fm

Mass Number	259
Neutron Number	159
Relative Atomic Mass	259.100596 ± 0.000304 Da
G-Factor
Abundance
Radioactivity	☢️ Radioactive
Half Life	1.5 ± 0.2 s
Spin
Quadrupole Moment
Discovery Year	1980
Parity

Decay Mode	Intensity
SF (spontaneous fission)	100%

²⁶⁰Fm

Mass Number	260
Neutron Number	160
Relative Atomic Mass	260.102809 ± 0.000467 Da
G-Factor	0
Abundance
Radioactivity	☢️ Radioactive
Half Life
Spin	0
Quadrupole Moment	0
Discovery Year
Parity	+

Decay Mode	Intensity
SF (spontaneous fission)

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

Discoverers	Argonne, Los Alamos, U of Calif
Discovery Location	United States
Discovery Year	1953
Etymology (Name Origin)	Named in honor of the scientist Enrico Fermi.
Pronunciation	FER-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

Frenchfermium
Norwegian Bokmålfermium
GermanFermium
Norwegian Nynorskfermium
Amharicፌርሚየም
Arabicفيرميوم
AzerbaijaniFermium
BelarusianФермій
Bulgarianфермий
Banglaফার্মিয়াম
Bosnianfermij
Catalanfermi
CorsicanFermiu
Czechfermium
ChuvashФерми
WelshFfermiwm
Danishfermium
Greekφέρμιο
Esperantofermio
Spanishfermio
Estonianfermium
Basquefermio
Persianفرمیم
Finnishfermium
FriulianFermi
Irishfeirmiam
GalicianFermio
ManxFermium
Hakka Chinesefermium
Hebrewפרמיום
Fiji HindiFermium
Croatianfermij
Haitian CreoleFèmyòm
Hungarianfermium
Armenianֆերմիում
Interlinguafermium
Indonesianfermium
Idofermio
Italianfermio
Japaneseフェルミウム
Lojbanjinmrfermi
JavaneseFermium
Kannadaಫೆರ್ಮಿಯಮ್
Korean페르뮴
KomiФермий
Latinfermium
LuxembourgishFermium
LigurianFermio
Lithuanianfermis
Latvianfermijs
Malayalamഫെർമിയം
Marathiफर्मियम
Western MariФермий
MalayFermium
Burmeseဖာမီယမ်
Dutchfermium
Polishferm
Portugueseférmio
QuechuaFermyu
Romanianfermiu
Russianфермий
YakutФермиум
Serbo-CroatianFermijum
Slovakfermium
Slovenianfermij
Albanianfermiumi
Serbianфермијум
Saterland FrisianFermium
Swedishfermium
Tamilபெர்மியம்
Thaiเฟอร์เมียม
Turkishfermiyum
Uyghurفېرمىي
Ukrainianфермій
Urdufermium
VepsFermii
Vietnamesefermi
WarayFermyo
KalmykФермиүм
YorubaFẹ́rmíọ̀m
Chinese鐨
CebuanoFermyo
Macedonianфермиум
Central Kurdishفێرمیۆم
Western Panjabiفرمئیم
BretonFermiom
KazakhФермий
PiedmonteseFermi
Odiaଫର୍ମିଅମ
Gujaratiફર્મીયમ
Occitanfermi
TatarФермий
Belarusian (Taraskievica orthography)Фэрм
German (Switzerland)Fermium
English (Canada)Fermium
English (United Kingdom)fermium
Portuguese (Brazil)férmio
Cantonese鐨
Hindiफर्मीयम
Newariफर्मियम
Sicilianfermiu
Chinese (China)镄
Chinese (Simplified)镄
Chinese (Traditional)鐨
Chinese (Hong Kong SAR China)鐨
Chinese (Taiwan)鐨
AromanianFermiu
KyrgyzФермий
FaroeseFermium
Sanskritफर्मियम
Maltesefermju
LimburgishFermium
Paliफर्मियम
Scottish GaelicFermium
Bhojpuriफर्मियम
Teluguఫర్మియం
Chinese (Macao SAR China)鐨
Chinese (Malaysia)镄
Chinese (Singapore)镄
AsturianFermio
Nepaliफर्मियम
UzbekFermiy
Lingua Franca Novafermio
TagalogPermiyo
Min Nan ChineseFermium
cdoFermium
AfrikaansFermium
kbpFɛrmɩyɔm
Volapükfermin
Northern FrisianFermium
oloFermii
Literary Chinese鐨
TajikФермий
Georgianფერმიუმი
Mongolianферми
Wu Chinese镄
SardinianFèrmiu
SwahiliFermi
Moroccan Arabicفيرميوم
BashkirФермий
Egyptian Arabicفيرميوم
Pashtoفېرميوم
CornishFermiom
BalineseFermium

Fermium on ChemicalAid

Australian Educational Vocabulary ID	scot/3519
CAS Registry Number	7440-72-4
ChEBI ID	33394
ChemSpider ID	22434
DSSTOX compound identifier	DTXCID60147884
DSSTox substance ID	DTXSID60225393
Den Store Danske ID	fermium
Encyclopædia Britannica Online ID	science/fermium
Encyclopædia Universalis ID	fermium
Freebase ID	/m/025rqck
GND ID	4490995-0
Gran Enciclopèdia Catalana ID	0108657
Great Russian Encyclopedia Online ID	4709674
InChI	InChI=1S/Fm
InChIKey	MIORUQGGZCBUGO-UHFFFAOYSA-N
KBpedia ID	Fermium
MeSH descriptor ID	D005286
OmegaWiki Defined Meaning	158627
PubChem CID	23998
Römpp online ID	RD-06-00507
Store norske leksikon ID	fermium
Treccani ID	fermio
UNII	Q70I3KBF4W
USGS Thesaurus ID	1453
WordNet 3.1 Synset ID	14661517-n

Fermium (Fm)

Physical Properties

Chemical Properties

Other

Isotopes of Fermium

241Fm

242Fm

243Fm

244Fm

245Fm

246Fm

247Fm

248Fm

249Fm

250Fm

251Fm

252Fm

253Fm

254Fm

255Fm

256Fm

257Fm

258Fm

259Fm

260Fm