Erbyum (Er)

chemical element with atomic number 68

Atomic Number	68
Atomic Weight	167.259
mass number	166

Group
Period	6
Block	f

proton	68 p⁺
neutron	98 n⁰
electron	68 e^-

Physical Property

Atomic Radius	175 pm 272 pm
molar volume	18.4 cm³/mol
covalent radius	165 pm 133 pm 189 pm
Metallic Radius
ionic radius	89 pm 94.5 pm 100.4 pm 106.2 pm
Crystal Radius	103 pm 108.5 pm 114.4 pm 120.2 pm
Van der Waals radius	229 pm 267 pm 339.1 pm
dosedh	9.07 g/cm³ 8,860 kg/m³

Chemical Property

nerth

proton affinity
electron affinity
ionization energy	6.1077 eV/particle 11.93 eV/particle 22.74 eV/particle 42.7 eV/particle 65.1 eV/particle 96 eV/particle 114 eV/particle 131 eV/particle 158 eV/particle 177 eV/particle 201 eV/particle 235 eV/particle 268 eV/particle 290 eV/particle 311 eV/particle 345 eV/particle 381 eV/particle 415 eV/particle 450 eV/particle 486 eV/particle 520 eV/particle 555 eV/particle 770 eV/particle 810 eV/particle 853 eV/particle 899 eV/particle 943 eV/particle 989 eV/particle 1,046 eV/particle 1,092 eV/particle 1,142 eV/particle 1,188 eV/particle 1,370 eV/particle 1,416 eV/particle 1,468 eV/particle 1,516 eV/particle 1,625 eV/particle 1,678 eV/particle 1,803 eV/particle 1,859 eV/particle 3,157 eV/particle 3,265 eV/particle 3,381 eV/particle 3,505 eV/particle 3,624 eV/particle 3,742 eV/particle 3,916 eV/particle 4,038 eV/particle 4,170 eV/particle 4,294 eV/particle 4,639 eV/particle 4,748 eV/particle 4,866 eV/particle 4,978 eV/particle 5,329 eV/particle 5,455 eV/particle 5,695 eV/particle 5,815 eV/particle 12,918 eV/particle 13,217 eV/particle 13,548 eV/particle 13,855 eV/particle 15,146 eV/particle 15,511 eV/particle 15,971 eV/particle 16,274.56 eV/particle 65,848.24 eV/particle 67,241.85 eV/particle

enthalpy of vaporization	317 kJ/mol
enthalpy of fusion
standard enthalpy of formation	316.4 kJ/mol
electron

electron shell	2, 8, 18, 30, 8, 2

valence electron	2 ⓘ

aray an elektrons	[Xe] 4f¹² 6s²ⓘ 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 4f¹² 6s²

oxidation number	0, 2, 3
electronegativity	0.212261 1.24
Electrophilicity Index
fundamental state of matter

phase of matter	Solid
gaseous state of matter
Boiling Point	3,141.15 K
Melting Point	1,802.15 K
critical pressure
critical temperature
triple point
appearance
liw	Silver #ff1493 #00e675 #00e675
appearance	silvery white
refractive index
thermodynamic material property
Thermal Conductivity
thermal expansion	0.0000122 1/K
molar heat capacity	28.12 J/(mol K)
Specific Heat Capacity	0.168 J/(g⋅K)
heat capacity ratio
electrical properties
type	Conductor
electrical conductivity	1.2 MS/m
electrical resistivity	0.00000086 Ω*m
superconductivity
magnetism
type	paramagnetic
magnetic susceptibility (Mass)	0.00000377 m³/Kg
magnetic susceptibility (Molar)	0.000000630566 m³/mol
magnetic susceptibility (Volume)	0.0341788
magnetic ordering
Curie temperature	32 K
Néel temperature	82 K
kesweyth
Crystal Structure	Simple Hexagonal (HEX)
lattice constant	3.56 Å
Lattice Angles	π/2, π/2, 2 π/3
mechanical property
hardness	814 MPa 589 MPa
bulk modulus	44 GPa
shear modulus	28 GPa
Young's modulus	70 GPa
Poisson's ratio	0.24
speed of sound	2,830 m/s
classification
Category	Lanthanides, Lanthanides
CAS Group
IUPAC Group
Glawe Number	22
Mendeleev Number	35
Pettifor Number	23
Geochemical Class	rare earth & related
Goldschmidt classification	litophile

other

Gas Basicity
polarizability	150 ± 10 a₀
C6 Dispersion Coefficient	2,150 a₀
allotrope
Neutron cross section	165
Neutron Mass Absorption	0.036
quantum number	3H6
space group	194 (P63/mmc)

Isotopes of Erbium

Stable Isotopes	3
Unstable Isotopes	36
Natural Isotopes	6

¹⁴²Er

mass number	142
neutron number	74
relative atomic mass	141.970016 ± 0.000537 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans
parity	+

decay mode	intensity
p (proton emission)

¹⁴³Er

mass number	143
neutron number	75
relative atomic mass	142.966548 ± 0.000429 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life
spin	9/2
nuclear quadrupole moment
dydhyas diskudhans	2005
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)
β⁺ p (β⁺-delayed proton emission)

¹⁴⁴Er

mass number	144
neutron number	76
relative atomic mass	143.9607 ± 0.00021 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	2003
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)

¹⁴⁵Er

mass number	145
neutron number	77
relative atomic mass	144.957874 ± 0.000215 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	900 ± 200 ms
spin	1/2
nuclear quadrupole moment	0
dydhyas diskudhans	1989
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)

¹⁴⁶Er

mass number	146
neutron number	78
relative atomic mass	145.952418357 ± 0.000007197 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	1.7 ± 0.6 s
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1993
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)

¹⁴⁷Er

mass number	147
neutron number	79
relative atomic mass	146.949964456 ± 0.000041 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	3.2 ± 1.2 s
spin	1/2
nuclear quadrupole moment	0
dydhyas diskudhans	1992
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)

¹⁴⁸Er

mass number	148
neutron number	80
relative atomic mass	147.944735026 ± 0.000011 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	4.6 ± 0.2 s
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1982
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	0.15%

¹⁴⁹Er

mass number	149
neutron number	81
relative atomic mass	148.942306 ± 0.00003 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	4 ± 2 s
spin	1/2
nuclear quadrupole moment	0
dydhyas diskudhans	1984
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	7%

¹⁵⁰Er

mass number	150
neutron number	82
relative atomic mass	149.937915524 ± 0.000018458 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	18.5 ± 0.7 s
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1982
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁵¹Er

mass number	151
neutron number	83
relative atomic mass	150.937448567 ± 0.000017681 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	23.5 ± 2 s
spin	7/2
nuclear quadrupole moment
dydhyas diskudhans	1970
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁵²Er

mass number	152
neutron number	84
relative atomic mass	151.935050347 ± 0.000009478 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	10.3 ± 0.1 s
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1963
parity	+

decay mode	intensity
α (α emission)	90%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	10%

¹⁵³Er

mass number	153
neutron number	85
relative atomic mass	152.93508635 ± 0.000009967 Da
g-factor	-0.26628571428571 ± 0.002
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	37.1 ± 0.2 s
spin	7/2
nuclear quadrupole moment	-0.42 ± 0.02
dydhyas diskudhans	1963
parity	-

decay mode	intensity
α (α emission)	53%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	47%

¹⁵⁴Er

mass number	154
neutron number	86
relative atomic mass	153.932790799 ± 0.000005325 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	3.73 ± 0.09 m
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1963
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
α (α emission)	0.47%

¹⁵⁵Er

mass number	155
neutron number	87
relative atomic mass	154.93321571 ± 0.00000652 Da
g-factor	-0.19028571428571 ± 0.0014285714285714
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	5.3 ± 0.3 m
spin	7/2
nuclear quadrupole moment	-0.27 ± 0.02
dydhyas diskudhans	1969
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	99.978%
α (α emission)	0.022%

¹⁵⁶Er

mass number	156
neutron number	88
relative atomic mass	155.931065926 ± 0.00002644 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	19.5 ± 1 m
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1967
parity	+

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
α (α emission)	1.2%

¹⁵⁷Er

mass number	157
neutron number	89
relative atomic mass	156.931922652 ± 0.000028454 Da
g-factor	-0.274 ± 0.002
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	18.65 ± 0.1 m
spin	3/2
nuclear quadrupole moment	0.92 ± 0.01
dydhyas diskudhans	1966
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁵⁸Er

mass number	158
neutron number	90
relative atomic mass	157.929893474 ± 0.000027074 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	2.29 ± 0.06 h
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1961
parity	+

decay mode	intensity
ϵ (electron capture)	100%

¹⁵⁹Er

mass number	159
neutron number	91
relative atomic mass	158.93069079 ± 0.00000391 Da
g-factor	-0.202 ± 0.0013333333333333
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	36 ± 1 m
spin	3/2
nuclear quadrupole moment	1.17 ± 0.01
dydhyas diskudhans	1962
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁶⁰Er

mass number	160
neutron number	92
relative atomic mass	159.929077193 ± 0.000026029 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	28.58 ± 0.09 h
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1954
parity	+

decay mode	intensity
ϵ (electron capture)	100%

¹⁶¹Er

mass number	161
neutron number	93
relative atomic mass	160.93000353 ± 0.000009419 Da
g-factor	-0.24266666666667 ± 0.002
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	3.21 ± 0.03 h
spin	3/2
nuclear quadrupole moment	1.363 ± 0.008
dydhyas diskudhans	1954
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁶²Er

mass number	162
neutron number	94
relative atomic mass	161.928787299 ± 0.000000811 Da
g-factor	0
natural abundance	0.139 ± 0.005
radioactivity	☢️ elven radyoweythresek
half-life
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1938
parity	+

decay mode	intensity
α (α emission)
2β⁺ (double β⁺ decay)

¹⁶³Er

mass number	163
neutron number	95
relative atomic mass	162.930039908 ± 0.000004967 Da
g-factor	0.2224 ± 0.0016
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	75 ± 0.4 m
spin	5/2
nuclear quadrupole moment	2.56 ± 0.02
dydhyas diskudhans	1953
parity	-

decay mode	intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁶⁴Er

mass number	164
neutron number	96
relative atomic mass	163.929207739 ± 0.000000755 Da
g-factor	0
natural abundance	1.601 ± 0.003
radioactivity	☢️ elven radyoweythresek
half-life
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1938
parity	+

decay mode	intensity
α (α emission)
2β⁺ (double β⁺ decay)

¹⁶⁵Er

mass number	165
neutron number	97
relative atomic mass	164.930733482 ± 0.000000985 Da
g-factor	0.2564 ± 0.0016
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	10.36 ± 0.04 h
spin	5/2
nuclear quadrupole moment	2.71 ± 0.03
dydhyas diskudhans	1950
parity	-

decay mode	intensity
ϵ (electron capture)	100%

¹⁶⁶Er

mass number	166
neutron number	98
relative atomic mass	165.930301067 ± 0.000000358 Da
g-factor	0
natural abundance	33.503 ± 0.036
radioactivity	stable isotope
half-life	Not Radioactive ☢️
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1934
parity	+

¹⁶⁷Er

mass number	167
neutron number	99
relative atomic mass	166.932056192 ± 0.000000306 Da
g-factor	-0.16065714285714 ± 0.00011428571428571
natural abundance	22.869 ± 0.009
radioactivity	stable isotope
half-life	Not Radioactive ☢️
spin	7/2
nuclear quadrupole moment	3.57 ± 0.03
dydhyas diskudhans	1934
parity	+

¹⁶⁸Er

mass number	168
neutron number	100
relative atomic mass	167.932378282 ± 0.00000028 Da
g-factor	0
natural abundance	26.978 ± 0.018
radioactivity	stable isotope
half-life	Not Radioactive ☢️
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1934
parity	+

¹⁶⁹Er

mass number	169
neutron number	101
relative atomic mass	168.934598444 ± 0.000000326 Da
g-factor	0.9656 ± 0.0008
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	9.392 ± 0.018 d
spin	1/2
nuclear quadrupole moment	0
dydhyas diskudhans	1956
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%

¹⁷⁰Er

mass number	170
neutron number	102
relative atomic mass	169.935471933 ± 0.000001488 Da
g-factor	0
natural abundance	14.91 ± 0.036
radioactivity	☢️ elven radyoweythresek
half-life
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1934
parity	+

decay mode	intensity
2β⁻ (double β⁻ decay)
α (α emission)

¹⁷¹Er

mass number	171
neutron number	103
relative atomic mass	170.938037372 ± 0.000001511 Da
g-factor	0.2628 ± 0.004
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	7.516 ± 0.002 h
spin	5/2
nuclear quadrupole moment	2.86 ± 0.09
dydhyas diskudhans	1938
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%

¹⁷²Er

mass number	172
neutron number	104
relative atomic mass	171.939363461 ± 0.000004253 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	49.3 ± 0.5 h
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1956
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%

¹⁷³Er

mass number	173
neutron number	105
relative atomic mass	172.9424 ± 0.00021 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	1.434 ± 0.017 m
spin	7/2
nuclear quadrupole moment
dydhyas diskudhans	1972
parity	-

decay mode	intensity
β⁻ (β⁻ decay)	100%

¹⁷⁴Er

mass number	174
neutron number	106
relative atomic mass	173.94423 ± 0.00032 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	3.2 ± 0.2 m
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	1989
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%

¹⁷⁵Er

mass number	175
neutron number	107
relative atomic mass	174.94777 ± 0.00043 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life	1.2 ± 0.3 m
spin	9/2
nuclear quadrupole moment
dydhyas diskudhans	1996
parity	+

decay mode	intensity
β⁻ (β⁻ decay)	100%

¹⁷⁶Er

mass number	176
neutron number	108
relative atomic mass	175.94994 ± 0.00043 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	2012
parity	+

decay mode	intensity
β⁻ (β⁻ decay)

¹⁷⁷Er

mass number	177
neutron number	109
relative atomic mass	176.95399 ± 0.00054 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life
spin	1/2
nuclear quadrupole moment	0
dydhyas diskudhans	2012
parity	-

decay mode	intensity
β⁻ (β⁻ decay)

¹⁷⁸Er

mass number	178
neutron number	110
relative atomic mass	177.956779 ± 0.00064 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	2012
parity	+

decay mode	intensity
β⁻ (β⁻ decay)

¹⁷⁹Er

mass number	179
neutron number	111
relative atomic mass	178.961267 ± 0.000537 Da
g-factor
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life
spin	3/2
nuclear quadrupole moment
dydhyas diskudhans	2018
parity	-

decay mode	intensity
β⁻ (β⁻ decay)
β⁻ n (β⁻-delayed neutron emission)

¹⁸⁰Er

mass number	180
neutron number	112
relative atomic mass	179.96438 ± 0.000537 Da
g-factor	0
natural abundance
radioactivity	☢️ elven radyoweythresek
half-life
spin	0
nuclear quadrupole moment	0
dydhyas diskudhans	2018
parity	+

decay mode	intensity
β⁻ (β⁻ decay)
β⁻ n (β⁻-delayed neutron emission)

istori

diskudher po dismyger	Carl Mosander
location of discovery	Sweden
dydhyas diskudhans	1843
Etymologyl	Named after the Swedish town, Ytterby.
pronunciation	UR-bi-em (en)

source

Abundance
Abundance in Earth's crust	3.5 mg/kg
natural abundance (Keynvor)	0.00000087 mg/L
natural abundance (Korf)
natural abundance (meteoroid)	0.000018 %
natural abundance (Howl)	0.0000001 %
Abundance in Universe	0.0000002 %

Nuclear Screening Constants

1	s	1.3263
2	p	4.346
2	s	17.7984
3	d	13.6397
3	p	20.3891
3	s	20.9231
4	d	35.7288
4	f	40.0216
4	p	32.8908
4	s	31.768
5	p	50.528
5	s	48.282
6	s	59.5238

Erbyum on ChemicalAid

Australian Educational Vocabulary ID	scot/3517
Brockhaus Enzyklopädie online ID	er-30
CAS Registry Number	7440-52-0
ChEBI ID	33379
ChemSpider ID	22416
DSSTOX compound identifier	DTXCID1047659
DSSTox substance ID	DTXSID8064694
De Agostini ID	èrbio
Den Store Danske ID	erbium
ECHA Substance Infocard ID	100.028.327
Elhuyar ZTH ID	023062
Encyclopædia Britannica Online ID	science/erbium
Encyclopædia Universalis ID	erbium
Freebase ID	/m/028bg3q
Great Russian Encyclopedia Online ID	4937360
InChI	InChI=1S/Er
InChIKey	UYAHIZSMUZPPFV-UHFFFAOYSA-N
KBpedia ID	Erbium
Library of Congress authority ID	sh85044573
MeSH descriptor ID	D004871
NALT ID	37808
Namuwiki ID	어븀
National Library of Israel J9U ID	987007552901505171
OmegaWiki Defined Meaning	158202
OpenAlex ID	C513967374
PubChem CID	23980
RxNorm ID	1311483
Römpp online ID	RD-05-01479
Store norske leksikon ID	erbium
Treccani ID	erbio
UNII	77B218D3YE
USGS Thesaurus ID	1447
WordNet 3.1 Synset ID	14661166-n
YSO ID	38979
ZVG number	7680
honanieth GND	4152588-7

Erbyum (Er)

Physical Property

Chemical Property

other

Isotopes of Erbium

142Er

143Er

144Er

145Er

146Er

147Er

148Er

149Er

150Er

151Er

152Er

153Er

154Er

155Er

156Er

157Er

158Er

159Er

160Er

161Er

162Er

163Er

164Er

165Er

166Er

167Er

168Er

169Er

170Er

171Er

172Er

173Er

174Er

175Er

176Er

177Er

178Er

179Er

180Er

istori

source

Nuclear Screening Constants

¹⁴²Er

¹⁴³Er

¹⁴⁴Er

¹⁴⁵Er

¹⁴⁶Er

¹⁴⁷Er

¹⁴⁸Er

¹⁴⁹Er

¹⁵⁰Er

¹⁵¹Er

¹⁵²Er

¹⁵³Er

¹⁵⁴Er

¹⁵⁵Er

¹⁵⁶Er

¹⁵⁷Er

¹⁵⁸Er

¹⁵⁹Er

¹⁶⁰Er

¹⁶¹Er

¹⁶²Er

¹⁶³Er

¹⁶⁴Er

¹⁶⁵Er

¹⁶⁶Er

¹⁶⁷Er

¹⁶⁸Er

¹⁶⁹Er

¹⁷⁰Er

¹⁷¹Er

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