Fermi (Fm)

chemical element with the atomic number of 100

Atomic Number	100
Atomic Weight	257
Rhif màs	241

Group
Period	7
Block	f

Proton	100 p⁺
Niwtron	141 n⁰
Electron	100 e^-

Nodwedd Ffisegol

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

Nodwedd Gemegol

egni

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

enthalpy of vaporization
enthalpy of fusion
standard enthalpy of formation
Electron

plisgyn yr electron	2, 8, 18, 32, 30, 8, 2

valence electron	2 ⓘ

trefn yr electronnau	[Rn] 5f¹² 7s²ⓘ 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 5f¹² 7s²

Cyflwr ocsidiad	2, 3
Electronegatifedd	0.22485
Electrophilicity Index
cyflwr sylfaenol mater

cyflwr mater	Solid
gaseous state of matter
Boiling Point
Melting Point	1,800.15 K
critical pressure
critical temperature
triple point
appearance
lliw	Colorless #ffffff #b31fba #b31fba
appearance
Mynegrif plygiant
nodwedd ffisegol gwrthrych
Thermal Conductivity
thermal expansion
molar heat capacity
Specific Heat Capacity
heat capacity ratio
electrical properties
type
dargludedd trydanol
Gwrthedd
superconductivity
magnetism
type
magnetic susceptibility (Mass)
magnetic susceptibility (Molar)
magnetic susceptibility (Volume)
magnetic ordering
Curie temperature
Néel temperature
strwythur
Crystal Structure	()
lattice constant
Lattice Angles
nodwedd mecanyddol deunyddiau
hardness
bulk modulus
shear modulus
Young's modulus
Poisson's ratio
speed of sound
classification
Category	Actinides, Actinides
CAS Group
IUPAC Group
Glawe Number	44
Mendeleev Number	36
Pettifor Number	37
Geochemical Class
Goldschmidt classification	synthetic

other

Gas Basicity
polarizability	113 ± 20 a₀
C6 Dispersion Coefficient
allotrope
Neutron cross section	5,800
Neutron Mass Absorption
quantum number	3H6
space group	()

Isotopes of Fermium

Stable Isotopes	0
Unstable Isotopes	20
Natural Isotopes	0

²⁴¹Fm

Rhif màs	241
neutron number	141
Relative Atomic Mass	241.074311 ± 0.000322 Da
g-factor
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	730 ± 60 us
spin	5/2
nuclear quadrupole moment
dyddiad darganfod	2008
parity	+

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

²⁴²Fm

Rhif màs	242
neutron number	142
Relative Atomic Mass	242.07343 ± 0.00043 Da
g-factor	0
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	800 ± 200 us
spin	0
nuclear quadrupole moment	0
dyddiad darganfod	1975
parity	+

decay mode	intensity
SF (spontaneous fission)	100%
α (α emission)

²⁴³Fm

Rhif màs	243
neutron number	143
Relative Atomic Mass	243.074414 ± 0.00014 Da
g-factor
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	231 ± 9 ms
spin	7/2
nuclear quadrupole moment
dyddiad darganfod	1981
parity	-

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

²⁴⁴Fm

Rhif màs	244
neutron number	144
Relative Atomic Mass	244.074036 ± 0.000216 Da
g-factor	0
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	3.12 ± 0.08 ms
spin	0
nuclear quadrupole moment	0
dyddiad darganfod	1967
parity	+

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

²⁴⁵Fm

Rhif màs	245
neutron number	145
Relative Atomic Mass	245.075354 ± 0.00021 Da
g-factor
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	4.2 ± 1.3 s
spin	1/2
nuclear quadrupole moment	0
dyddiad darganfod	1967
parity	+

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

²⁴⁶Fm

Rhif màs	246
neutron number	146
Relative Atomic Mass	246.075353334 ± 0.000014675 Da
g-factor	0
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	1.54 ± 0.04 s
spin	0
nuclear quadrupole moment	0
dyddiad darganfod	1966
parity	+

decay mode	intensity
α (α emission)	93.2%
SF (spontaneous fission)	6.8%
ϵ (electron capture)	1.3%

²⁴⁷Fm

Rhif màs	247
neutron number	147
Relative Atomic Mass	247.076944 ± 0.000194 Da
g-factor
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	31 ± 1 s
spin	7/2
nuclear quadrupole moment
dyddiad darganfod	1967
parity	+

decay mode	intensity
α (α emission)	64%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)

²⁴⁸Fm

Rhif màs	248
neutron number	148
Relative Atomic Mass	248.077185451 ± 0.000009122 Da
g-factor	0
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	34.5 ± 1.2 s
spin	0
nuclear quadrupole moment	0
dyddiad darganfod	1958
parity	+

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

²⁴⁹Fm

Rhif màs	249
neutron number	149
Relative Atomic Mass	249.078926042 ± 0.000006668 Da
g-factor
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	1.6 ± 0.1 m
spin	7/2
nuclear quadrupole moment
dyddiad darganfod	1960
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)
α (α emission)	33%

²⁵⁰Fm

Rhif màs	250
neutron number	150
Relative Atomic Mass	250.079519765 ± 0.000008468 Da
g-factor	0
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	31 ± 1.1 m
spin	0
nuclear quadrupole moment	0
dyddiad darganfod	1954
parity	+

decay mode	intensity
α (α emission)	100%
SF (spontaneous fission)	0.0069%
ϵ (electron capture)

²⁵¹Fm

Rhif màs	251
neutron number	151
Relative Atomic Mass	251.08154513 ± 0.000015342 Da
g-factor
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	5.3 ± 0.08 h
spin	9/2
nuclear quadrupole moment
dyddiad darganfod	1957
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	98.2%
α (α emission)	1.8%

²⁵²Fm

Rhif màs	252
neutron number	152
Relative Atomic Mass	252.082466019 ± 0.000005604 Da
g-factor	0
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	25.39 ± 0.04 h
spin	0
nuclear quadrupole moment	0
dyddiad darganfod	1956
parity	+

decay mode	intensity
α (α emission)	100%
SF (spontaneous fission)	0.0023%
2β⁺ (double β⁺ decay)

²⁵³Fm

Rhif màs	253
neutron number	153
Relative Atomic Mass	253.085180945 ± 0.000001662 Da
g-factor
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	3 ± 0.12 d
spin	1/2
nuclear quadrupole moment	0
dyddiad darganfod	1957
parity	+

decay mode	intensity
ϵ (electron capture)	88%
α (α emission)	12%

²⁵⁴Fm

Rhif màs	254
neutron number	154
Relative Atomic Mass	254.086852424 ± 0.000001978 Da
g-factor	0
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	3.24 ± 0.002 h
spin	0
nuclear quadrupole moment	0
dyddiad darganfod	1954
parity	+

decay mode	intensity
α (α emission)	99.9408%
SF (spontaneous fission)	0.0592%

²⁵⁵Fm

Rhif màs	255
neutron number	155
Relative Atomic Mass	255.089963495 ± 0.000004223 Da
g-factor
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	20.07 ± 0.07 h
spin	7/2
nuclear quadrupole moment
dyddiad darganfod	1954
parity	+

decay mode	intensity
α (α emission)	100%
SF (spontaneous fission)	2.4%

²⁵⁶Fm

Rhif màs	256
neutron number	156
Relative Atomic Mass	256.091771699 ± 0.000003241 Da
g-factor	0
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	157.1 ± 1.3 m
spin	0
nuclear quadrupole moment	0
dyddiad darganfod	1955
parity	+

decay mode	intensity
SF (spontaneous fission)	91.9%
α (α emission)	8.1%

²⁵⁷Fm

Rhif màs	257
neutron number	157
Relative Atomic Mass	257.095105419 ± 0.000004669 Da
g-factor
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	100.5 ± 0.2 d
spin	9/2
nuclear quadrupole moment
dyddiad darganfod	1964
parity	+

decay mode	intensity
α (α emission)	99.79%
SF (spontaneous fission)	0.21%

²⁵⁸Fm

Rhif màs	258
neutron number	158
Relative Atomic Mass	258.097077 ± 0.000215 Da
g-factor	0
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	370 ± 14 us
spin	0
nuclear quadrupole moment	0
dyddiad darganfod	1971
parity	+

decay mode	intensity
SF (spontaneous fission)	100%
α (α emission)

²⁵⁹Fm

Rhif màs	259
neutron number	159
Relative Atomic Mass	259.100596 ± 0.000304 Da
g-factor
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes	1.5 ± 0.2 s
spin
nuclear quadrupole moment
dyddiad darganfod	1980
parity

decay mode	intensity
SF (spontaneous fission)	100%

²⁶⁰Fm

Rhif màs	260
neutron number	160
Relative Atomic Mass	260.102809 ± 0.000467 Da
g-factor	0
natural abundance
Dadfeilio ymbelydrol	☢️ elfen ymbelydrol
Hanner oes
spin	0
nuclear quadrupole moment	0
dyddiad darganfod
parity	+

decay mode	intensity
SF (spontaneous fission)

hanes

darganfyddwr neu ddyfeisiwr	Argonne, Los Alamos, U of Calif
man darganfod	United States
dyddiad darganfod	1953
geirdarddiad	Named in honor of the scientist Enrico Fermi.
ynganiad	FER-mi-em (Saesneg)

source

Abundance
Abundance in Earth's crust
natural abundance (cefnfor)
natural abundance (corff dynol)	0 %
natural abundance (Awyrfaen)	0 %
natural abundance (Haul)	0 %
Abundance in Universe	0 %

Nuclear Screening Constants

Fermi on ChemicalAid

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

Fermi (Fm)

Nodwedd Ffisegol

Nodwedd Gemegol

other

Isotopes of Fermium

241Fm

242Fm

243Fm

244Fm

245Fm

246Fm

247Fm

248Fm

249Fm

250Fm

251Fm

252Fm

253Fm

254Fm

255Fm

256Fm

257Fm

258Fm

259Fm

260Fm

hanes

source

Nuclear Screening Constants

²⁴¹Fm

²⁴²Fm

²⁴³Fm

²⁴⁴Fm

²⁴⁵Fm

²⁴⁶Fm

²⁴⁷Fm

²⁴⁸Fm

²⁴⁹Fm

²⁵⁰Fm

²⁵¹Fm

²⁵²Fm

²⁵³Fm

²⁵⁴Fm

²⁵⁵Fm

²⁵⁶Fm

²⁵⁷Fm

²⁵⁸Fm

²⁵⁹Fm

²⁶⁰Fm