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Periodic Table
Periodic

Holmium

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Holmium

Atomic Mass	164.93033
Electron Configuration	[Xe]6s24f11
Oxidation States	+3
Year Discovered	1878

Holmium

Atomic Mass	164.93033
Electron Configuration	[Xe]6s24f11
Oxidation States	+3
Year Discovered	1878

Identifiers

Element Name	Holmium
Element Symbol	Ho
InChI	InChI=1S/Ho
InChIKey	KJZYNXUDTRRSPN-UHFFFAOYSA-N

Properties

Atomic Weight	164.930 329(5) 164.93033 164.9 164.93033(2)
Electron Configuration	[Xe]6s²4f¹¹
Atomic Radius	Van der Waals Atomic Radius : 216 pm (Van der Waals) Empirical Atomic Radius : 175pm (Empirical) Covalent Atomic Radius : 192(7) pm (Covalent)
Oxidation States	+3 3, 2, 1 (a basic oxide)
Ground Level	⁴I°_15/2
Ionization Energy	6.022 eV 6.0215 ± 0.0006 eV
Electronegativity	Pauling Scale Electronegativity : 1.23(Pauling Scale)
Atomic Spectra	Lines Holdings Levels Holdings
Physical Description	Solid
Element Classification	Metal
Element Period Number	6
Element Group Number	- Lanthanide
Density	8.80 grams per cubic centimeter
Melting Point	1747 K (1474°C or 2685°F) 1461°C
Boiling Point	2973 K (2700°C or 4892°F) 2600°C
Estimated Crustal Abundance	1.3 milligrams per kilogram
Estimated Oceanic Abundance	2.2×10^-7 milligrams per liter

History

The name derives from the Latin holmia for Stockholm. It was discovered in erbia earth by the Swiss chemist J. L. Soret in 1878, who referred to it as element X. It was later independently discovered by the Swedish chemist Per Theodor Cleve in 1879. It was first isolated in 1911 by Homberg, who proposed the name holmium either to recognize the discoverer Per Cleve, who was from Stockholm, or perhaps to establish his own name in history.

Holmium was discovered by Per Theodor Cleve, a Swedish chemist, in 1879. Cleve used the same method Carl Gustaf Mosander used to discover lanthanum, erbium and terbium, he looked for impurities in the oxides of other rare earth elements. He started with erbia, the oxide of erbium (Er2O3), and removed all of the known contaminants. After further processing, he obtained two new materials, one brown and the other green. Cleve named the brown material holmia and the green material thulia. Holmia is the oxide of the element holmium and thulia is the oxide of the element thulium. Holmium's absorption spectrum was observed earlier that year by J. L. Soret and M. Delafontaine, Swiss chemists. Today, holmium is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements that can contain as much as 0.05% holmium. Holmium has no commercial applications, although it has unusual magnetic properties that could be exploited in the future.

Holmium forms no commercially important compounds. Some of holmium's compounds include: holmium oxide (Ho2O3), holmium fluoride (HoF3) and holmium iodide (HoI3).

From the Latin word Holmia meaning Stockholm. The special absorption bands of holmium were noticed in 1878 by the Swiss chemists Delafontaine and Soret, who announced the existence of an "Element X." Cleve, of Sweden, later independently discovered the element while working on erbia earth. The element is named after Cleve's native city. Holmia, the yellow oxide, was prepared by Homberg in 1911. Holmium occurs in gadolinite, monazite, and in other rare-earth minerals. It is commercially obtained from monazite, occurring in that mineral to the extent of about 0.05%. It has been isolated by the reduction of its anhydrous chloride or fluoride with calcium metal.

Historical Atomic Weights

Year	Atomic Weight (uncertainty) [u]	Reference
2021	164.930 329(5)	https://doi.org/10.1515/pac-2019-0603
2017	164.930 328(7)	https://doi.org/10.1515/pac-2019-0603
2013	164.930 33(2)	https://doi.org/10.1515/pac-2015-0305
1995	164.930 32(2)	https://doi.org/10.1351/pac199668122339
1985	164.930 32(3)	https://doi.org/10.1351/pac198658121677
1971	164.9304(1)	https://doi.org/10.1351/pac197230030637
1969	164.9303(1)	https://doi.org/10.1351/pac197021010091
1961	164.930	https://doi.org/10.1021/ja00881a001
1941	164.94	https://doi.org/10.1039/JR9410000146
1931	163.5	https://doi.org/10.1039/JR9310001617
1925	163.4	https://doi.org/10.1039/CT9252700913
1913	163.5	https://doi.org/10.1021/ja02212a001

Historical Isotopic Abundances

Year	Isotope	Abundance (uncertainty)	Reference
1975, ¹⁶⁵Ho, 1, doi:10.1351/pac197647010075

Description

Pure holmium has a metallic to bright silver luster. It is relatively soft and malleable and is stable in dry air at room temperature but rapidly oxidizes in moist air and at elevated temperatures. The metal has unusual magnetic properties. Few uses have yet been found for the element. The element, as with other rare earths, seems to have a low acute toxic rating.

Compounds

See more information at the Holmium compound page.

Element Forms

CID	Name	Formula	SMILES	Molecular Weight
23988	holmium	Ho	[Ho]	164.93033
185493	holmium(3+)	Ho+3	[Ho+3]	164.93033
161007	holmium-166	Ho	[166Ho]	165.932291
177427	holmium-161	Ho	[161Ho]	160.92786
177669	holmium-167	Ho	[167Ho]	166.93314
177569	holmium-155	Ho	[155Ho]	154.9291
177626	holmium-162	Ho	[162Ho]	161.92910
177667	holmium-164	Ho	[164Ho]	163.93024
177668	holmium-159	Ho	[159Ho]	158.92772
177693	holmium-157	Ho	[157Ho]	156.9283
42630750	holmium-156	Ho	[156Ho]	155.9296
51352784	holmium-166(3+)	Ho+3	[166Ho+3]	165.932291

Isotopes

Stable Isotope Count	1

Isotopes in Medicine

Radiosynovectomy with 166Ho-radiopharmaceutical agents can be used for treatment of arthritis. The half-life of 166Ho is 1.1 days. 166Ho ferric hydroxide macroaggregate ([ 166Ho] FHMA) radiosynovectomy is being used because FHMA minimizes extra-articular (outside a joint) leakage of the radioisotope [472], [473]. 166Ho has been used for radioimmunotherapy (RIT) with labeled antibodies [474]. The 166Ho-chitosan complex (a linear polysaccharide, which is a long-chain molecule like cellulose that is used by the body for energy storage) is being used for hepatic (liver) cancer therapy [475]. 166Ho-labeled radiopharmaceuticals have been used for alleviating pain from bone metastases [443], [473], [476].

166Ho microspheres have been used for intra-arterial radioembolization (treatment where radioactive particles are delivered to a tumor through the bloodstream) of liver metastases (Fig. IUPAC.67.1) [475]. 166Ho is paramagnetic and emits both beta and gamma radiation, which makes it ideal for radioembolization. These properties also enable the distribution of 166Ho microspheres to be visualized with magnetic resonance imaging and single-photon emission computed tomography (SPECT) [475].

The 166Ho-Patch is a specially designed radioactive skin patch that is used for external radiation of superficial skin cancers and Bowen’s disease in areas that are sensitive and difficult to treat by methods that are more destructive and have poor cosmetic results (i.e. areas of the face) [477], [478].

Fig. IUPAC.67.1: Schematic overview of the administration system for ¹⁶⁶Ho-RE (radioembolization) (reprinted with permission. Copyright © 2010 Smits et al.; BioMed Central Ltd.) [475]. The administration system consists of the following components: iodine contrast agent (Visipaque ®, GE Healthcare) (1), saline solution (2), 20-ml syringe (Luer-Lock) (3), three-stopcock manifold (4), one-way valve (5), inlet line (6), administration vial containing the ¹⁶⁶Ho-poly(L-lactic acid) microspheres (7), outlet line (8), flushing line (9), Y-connector (10) and catheter (11).

[443] International Atomic Energy Agency. Optimization of Production and Quality Control of Therapeutic Radionuclides and Radiopharmaceuticals, IAEA-TECDOC-1114, IAEA VIENNA (1999).

[472] S. Zeisler, K. Weber. J. Radioanal. Nucl. Chem.227, 105 (1998).

[473] O. T. Mäkelä, M. J. Lammi, H. Uusitalo, M. M. Hyttinen, E. Vuorio, H. J. Helminen, R. M. Tulamo. Ann. Rheum. Dis.62, 43 (2003).

[474] H. Mohsin, F. Jia, G. Sivaguru, M. J. Hudson, T. D. Shelton, T. J. Hoffman, C. S. Cutler, A. R. Ketring, P. S. Athey, J. Simon, R. K. Frank, S. S. Jurisson, M. R. Lewis. Bioconjugate Chem.17, 485 (2006).

[475] M. L. Smits, J. F. Nijsen, M. A. van den Bosch, M. G. Lam, M. A. Vente, J. E. Huijbregts, A. D. van het Schip, M. Elschot, W. Bult, H. W. de Jong, P. C. Meulenhoff, B. A. Zonnenberg. J. Exp. Clin. Cancer Res.29, 70 (2010).

[476] F. Melichar, M. Kropacek, M. Mirzajevova. J. Label. Compd. Radiopharm.46 (S1), S303 (2003). https://onlinelibrary.wiley.com/doi/abs/10.1002/jlcr.772.

[477] J. D. Lee, K. K. Park, M. G. Lee, E. H. Kim, K. J. Rhim, J. T. Lee, H. S. Yoo, Y. M. Kim, K. B. Park, J. R. Kim. J. Nucl. Med.38, 697 (1997).

[478] Y. L. Chung, J. D. Lee, D. Bang, J. B. Lee, K. B. Park, M. G. Lee. Eur. J. Nucl. Med. Mol. Imaging27, 842 (2000).

Isotope Mass and Abundance

Isotope	Atomic Mass (uncertainty) [u]	Abundance (uncertainty)
^165Ho	164.930 329(5)	1

Isotope	Atomic Mass (uncertainty) [u]	Abundance (uncertainty)
¹⁶⁵Ho	164.9303288(21)	1

Atomic Mass, Half Life, and Decay

Nuclide	Atomic Mass and Uncertainty [u]	Half Life and Uncertainty	Discovery Year	Decay Modes, Intensities and Uncertainties [%]
¹⁴⁰Ho	139.968526 ± 0.000537 [Estimated]	6 ms ± 3	1999	p=?; β⁺ ?; β⁺p ?
¹⁴¹Ho	140.963108 ± 0.00043 [Estimated]	4.1 ms ± 0.1	1998	p≈100%; β⁺ ?; β⁺p ?
¹⁴¹Ho^m	140.963108 ± 0.00043 [Estimated]	7.3 us ± 0.3	1998	p=100%
¹⁴²Ho	141.960010 ± 0.00043 [Estimated]	400 ms ± 100	2001	β⁺≈100%; β⁺p=?; p≈0%
¹⁴³Ho	142.954860 ± 0.00032 [Estimated]	300 ms >200ns [Estimated]	2000	β⁺ ?; β⁺p ?
¹⁴⁴Ho	143.952109712 ± 0.0000091	700 ms ± 100	1986	β⁺=100%; β⁺p=?
¹⁴⁴Ho^m	143.952109712 ± 0.0000091	519 ns ± 5	2001	IT=100%
¹⁴⁵Ho	144.947267392 ± 0.000008	2.4 s ± 0.1	1987	β⁺=100%
¹⁴⁵Ho^m	144.947267392 ± 0.000008	100 ms [Estimated]		β⁺ ?; IT ?
¹⁴⁶Ho	145.944993503 ± 0.000007071	3.32 s ± 0.22	1982	β⁺=100%; β⁺p=?
¹⁴⁷Ho	146.940142293 ± 0.000005368	5.8 s ± 0.4	1982	β⁺=100%
¹⁴⁷Ho^m	146.940142293 ± 0.000005368	315 ns ± 30	1982	IT=100%
¹⁴⁸Ho	147.937743925 ± 0.00009	2.2 s ± 1.1	1979	β⁺=100%
¹⁴⁸Ho^m	147.937743925 ± 0.00009	9.49 s ± 0.12	1979	β⁺=100%; β⁺p=0.08±0.1%
¹⁴⁸Hoⁿ	147.937743925 ± 0.00009	2.36 ms ± 0.06	1984	IT=100[gs=0,m=100]
¹⁴⁹Ho	148.933820457 ± 0.000012866	21.1 s ± 0.2	1979	β⁺=100%
¹⁴⁹Ho^m	148.933820457 ± 0.000012866	56 s ± 3	1988	β⁺=100%
¹⁵⁰Ho	149.933498353 ± 0.000015209	76.8 s ± 1.8	1963	β⁺=100%
¹⁵⁰Ho^m	149.933498353 ± 0.000015209	23.3 s ± 0.3	1980	β⁺=100%
¹⁵⁰Hoⁿ	149.933498353 ± 0.000015209	787 ns ± 36	2006	IT=100%
¹⁵¹Ho	150.931698176 ± 0.000008908	35.2 s ± 0.1	1963	β⁺=88±0.3%; α=22±0.3%
¹⁵¹Ho^m	150.931698176 ± 0.000008908	47.2 s ± 1.3	1963	α=77±1.8%; β⁺=23±1.8%
¹⁵²Ho	151.931717618 ± 0.000013449	161.8 s ± 0.3	1963	β⁺=88±0.3%; α=12±0.3%
¹⁵²Ho^m	151.931717618 ± 0.000013449	49.8 s ± 0.2	1963	β⁺=89.2±1.7%; α=10.8±1.7%
¹⁵²Hoⁿ	151.931717618 ± 0.000013449	8.4 us ± 0.3	1997	IT=100%
¹⁵³Ho	152.930206671 ± 0.000005438	2.01 m ± 0.03	1963	β⁺=99.949±2.5%; α=0.051±2.5%
¹⁵³Ho^m	152.930206671 ± 0.000005438	9.3 m ± 0.5	1963	β⁺=99.82±0.8%; α=0.18±0.8%
¹⁵³Hoⁿ	152.930206671 ± 0.000005438	229 ns ± 2	1980	IT=100%
¹⁵⁴Ho	153.930606776 ± 0.00000882	11.76 m ± 0.19	1966	β⁺=99.981±0.5%; α=0.019±0.5%
¹⁵⁴Ho^m	153.930606776 ± 0.00000882	3.10 m ± 0.14	1968	β⁺=100%; α<0.001%; IT≈0%
¹⁵⁵Ho	154.929103363 ± 0.000018754	48 m ± 2	1959	β⁺=100%
¹⁵⁵Ho^m	154.929103363 ± 0.000018754	880 us ± 80	1984	IT=100%
¹⁵⁶Ho	155.929641634 ± 0.000041249	56 m ± 1	1957	β⁺=100%
¹⁵⁶Ho^m	155.929641634 ± 0.000041249	9.5 s ± 1.5	1995	IT≈100%; β⁺ ?
¹⁵⁶Hoⁿ	155.929641634 ± 0.000041249	7.6 m ± 0.3	1975	β⁺≈75%; IT ?
¹⁵⁷Ho	156.928251974 ± 0.000025194	12.6 m ± 0.2	1966	β⁺=100%
¹⁵⁸Ho	157.928944910 ± 0.000029099	11.3 m ± 0.4	1961	β⁺≈100%; α ?
¹⁵⁸Ho^m	157.928944910 ± 0.000029099	28 m ± 2	1960	IT≈91±0.6%; β⁺≈9±0.6%
¹⁵⁸Hoⁿ	157.928944910 ± 0.000029099	140 ns ± 25	2005	IT=100%
¹⁵⁸Ho^p	157.928944910 ± 0.000029099	21.3 m ± 2.3	1970	β⁺≈100%; IT ?
¹⁵⁹Ho	158.927718683 ± 0.000003268	33.05 m ± 0.11	1958	β⁺=100%
¹⁵⁹Ho^m	158.927718683 ± 0.000003268	8.30 s ± 0.08	1966	IT=100%
¹⁶⁰Ho	159.928735538 ± 0.00001612	25.6 m ± 0.3	1950	β⁺=100%
¹⁶⁰Ho^m	159.928735538 ± 0.00001612	5.02 h ± 0.05	1955	IT=73±0.3%; β⁺=27±0.3%
¹⁶⁰Hoⁿ	159.928735538 ± 0.00001612	~3 s	1988	IT=100%
¹⁶¹Ho	160.927861815 ± 0.000002309	2.48 h ± 0.05	1954	ε=100%
¹⁶¹Ho^m	160.927861815 ± 0.000002309	6.76 s ± 0.07	1965	IT=100%
¹⁶²Ho	161.929102543 ± 0.00000333	15.0 m ± 1.0	1957	β⁺=100%
¹⁶²Ho^m	161.929102543 ± 0.00000333	67.0 m ± 0.7	1961	IT=62%; β⁺=38%
¹⁶³Ho	162.928740260 ± 0.000000744	4.570 ky ± 0.025	1957	ε=100%
¹⁶³Ho^m	162.928740260 ± 0.000000744	1.09 s ± 0.03	1957	IT=100%
¹⁶³Hoⁿ	162.928740260 ± 0.000000744	800 ns ± 150	2012	IT=100%
¹⁶⁴Ho	163.930240548 ± 0.000001492	28.8 m ± 0.5	1938	ε=61±0.1%; β⁺=39±0.1%
¹⁶⁴Ho^m	163.930240548 ± 0.000001492	36.6 m ± 0.3	1966	IT=100%
¹⁶⁵Ho	164.930329116 ± 0.000000844	Stable	1934	IS=100%
¹⁶⁵Ho^m	164.930329116 ± 0.000000844	1.512 us ± 0.004	1958	IT=100%
¹⁶⁵Hoⁿ	164.930329116 ± 0.000000844	<100 ns	1958	IT=100%
¹⁶⁶Ho	165.932291209 ± 0.000000844	26.812 h ± 0.007	1936	β^-=100%
¹⁶⁶Ho^m	165.932291209 ± 0.000000844	1.1326 ky ± 0.0039	1952	β^-=100%
¹⁶⁶Hoⁿ	165.932291209 ± 0.000000844	185 us ± 15	1960	IT=100%
¹⁶⁷Ho	166.933140254 ± 0.00000557	3.1 h ± 0.1	1955	β^-=100%
¹⁶⁷Ho^m	166.933140254 ± 0.00000557	6.0 us ± 1.0	1977	IT=100%
¹⁶⁸Ho	167.935523766 ± 0.000032207	2.99 m ± 0.07	1960	β^-=100%
¹⁶⁸Ho^m	167.935523766 ± 0.000032207	132 s ± 4	1990	IT≈100%; β^- ?
¹⁶⁸Hoⁿ	167.935523766 ± 0.000032207	>4 us	1990	IT=100%
¹⁶⁸Ho^p	167.935523766 ± 0.000032207	108 ns ± 11	1990	IT=100%
¹⁶⁹Ho	168.936879890 ± 0.000021522	4.72 m ± 0.10	1963	β^-=100%
¹⁶⁹Ho^m	168.936879890 ± 0.000021522	118 us ± 6	2010	IT=100%
¹⁷⁰Ho	169.939626548 ± 0.000053697	2.76 m ± 0.05	1960	β^-=100%
¹⁷⁰Ho^m	169.939626548 ± 0.000053697	43 s ± 2	1960	β^-=100%
¹⁷¹Ho	170.941472713 ± 0.000644128	53 s ± 2	1989	β^-=100%
¹⁷²Ho	171.944730 ± 0.00021 [Estimated]	25 s ± 3	1991	β^-=100%
¹⁷³Ho	172.947020 ± 0.00032 [Estimated]	7.1 s ± 0.4	2012	β^-=100%
¹⁷³Ho^m	172.947020 ± 0.00032 [Estimated]	3.7 us ± 1.2	2020	IT=100%
¹⁷⁴Ho	173.950757 ± 0.000322 [Estimated]	3.7 s ± 0.4	2012	β^-=100%
¹⁷⁵Ho	174.953516 ± 0.000429 [Estimated]	1.88 s ± 0.55	2012	β^-=100%; β^-n ?
¹⁷⁶Ho	175.957713 ± 0.000537 [Estimated]	1 s >300ns [Estimated]	2012	β^- ?; β^-n ?
¹⁷⁷Ho	176.961052 ± 0.000537 [Estimated]	1 s >550ns [Estimated]	2018	β^-=100%; n ?
¹⁷⁸Ho	177.965507 ± 0.000537 [Estimated]	750 ms >550ns [Estimated]	2018	β^- ?; β^-n ?

Information Sources

1. PubChem

https://pubchem.ncbi.nlm.nih.gov
2. Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)

LICENSE
https://www-nds.iaea.org/disclaimer.html

Ho
https://www-nds.iaea.org/amdc/
3. IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)

LICENSE
http://www.ciaaw.org/bylaws.htm

Holmium
https://www.ciaaw.org/holmium.htm
4. Jefferson Lab, U.S. Department of Energy

LICENSE
Please see citation and linking information https https://www.jlab.org/privacy-and-security-notice

Holmium
https://education.jlab.org/itselemental/ele067.html
5. Los Alamos National Laboratory, U.S. Department of Energy

LICENSE
https://about.lanl.gov/lanl-resources/web-policies/

Holmium
https://periodic.lanl.gov/67.shtml
6. NIST Physical Measurement Laboratory

LICENSE
https://www.nist.gov/pml/database-disclaimer

Holmium
https://physics.nist.gov/cgi-bin/Elements/elInfo.pl?element=67
7. IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

LICENSE
Copyright (c) 2020 International Union of Pure and Applied Chemistry. The International Union of Pure and Applied Chemistry (IUPAC) contribution within Pubchem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.
https://creativecommons.org/licenses/by-nc-nd/4.0/

https://doi.org/10.1515/pac-2015-0703
8. PubChem Elements

LICENSE
https://www.nlm.nih.gov/copyright.html

Holmium

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