Sc 21

Scandium (Sc)

transition-metal

Period: 4 Group: 3 Block: s

Solid

Standard Atomic Weight

Electron configuration

[Ar] 4s² 3d¹

Melting point

1540.85 °C (1814 K)

Boiling point

2835.85 °C (3109 K)

Density

2990 kg/m³

Oxidation states

0, +1, +2, +3

Electronegativity (Pauling)

1.36

Ionization energy (1st)

Discovery year

1879

Atomic radius

160 pm

Details

Name origin Latin: Scandia, Scandinavia.

Discovery country Sweden

Discoverers Lars Nilson

Scandium is a light transition metal with chemistry dominated by the +3 oxidation state. It is chemically similar to yttrium and the lanthanides, but its small ionic radius gives some distinct coordination behavior. The element is widely dispersed in minerals and rarely occurs in rich, easily worked ores. Its technological importance is concentrated in specialty aluminum alloys, high-intensity lighting, and research materials rather than large-volume metal use.

Scandium is a silver-white metal which develops a slightly yellowish or pinkish cast upon exposure to air. A relatively soft element, scandium resembles yttrium and the rare-earth metals more than it resembles aluminum or titanium.

It is a very light metal and has a much higher melting point than aluminum, making it of interest to designers of spacecraft. Scandium is not attacked by a 1:1 mixture of HNO3 and 48% HF.

Chemically it is one of the alkaline earth elements; it readily forms a white coating of nitride in air, reacts with water, burns with a yellow-red flame.

The name derives from the Latin scandia for Scandinavia, where the mineral was found. It was discovered by the Swedish chemist Lars-Fredrik Nilson in 1879 in an ytterbium sample. In the same year, the Swedish chemist Per Theodore Cleve proved that scandium was Mendeleev's predicted "eka-boron".

Scandium was discovered by Lars Fredrik Nilson, a Swedish chemist, in 1879 while attempting to produce a sample of pure ytterbia from 10 kilograms of the mineral euxenite ((Y, Ca, Er, La, Ce, U, Th)(Nb, Ta, Ti)2O6). Scandium can be obtained from the minerals thortveitite ((Sc, Y)2Si2O7), bazzite (Be3(Sc, Al)2Si6O18) and wiikite, but is usually obtained as a byproduct of refining uranium. Metallic scandium was first produced in 1937 and the first pound (0.45 kilograms) of pure scandium was produced in 1960. Scandium is a soft, light metal that might have applications in the aerospace industry. With a cost of $270 per gram ($122,500 per pound), scandium is too expensive for widespread use.

From the Latin word Scandia, Scandinavia. On the basis of the Periodic System, Mendeleev predicted the existence of ekaboron, which would have an atomic weight between 40 of calcium and 48 of titanium. The element was discovered by Nilson in 1878 in the minerals euxenite and gadolinite, which had not yet been found anywhere except in Scandinavia. By processing 10 kg of euxenite and other residues of rare-earth minerals, Nilson was able to prepare about 2g of highly pure scandium oxide. Later scientists pointed out that Nilson's scandium was identical with Mendeleev's ekaboron.

Read about Scandium on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 160 pm

Covalent radius 170 pm

Van der Waals radius 211 pm

Metallic radius 144 pm

Density

Molar volume 0.015 L/mol

Phase at STP solid

Melting point 1540.85 °C

Boiling point 2835.85 °C

Thermal conductivity 15.8 W/(m·K)

Specific heat capacity 0.568 J/(g·K)

Molar heat capacity 25.52 J/(mol·K)

Crystal structure hcp

Chemical

Electronegativity (Pauling) 1.36

Electronegativity (Allen) 1.19

Electron affinity

Ionization energy (1st)

Ionization energy (2nd)

Ionization energy (3rd)

Ionization energy (4th)

Ionization energy (5th)

Oxidation states 0, +1, +2, +3

Valence electrons 3

Electron configuration

Electron configuration (semantic)

Thermodynamic

Heat of fusion 0.16582889 eV

Heat of vaporization 3.256465 eV

Heat of sublimation 3.923926 eV

Heat of atomization 3.923926 eV

Atomization enthalpy

Nuclear

Stable isotopes 1

Discovery year 1879

Abundance

Abundance (Earth's crust) 22 mg/kg

Abundance (ocean)

Reactivity

N/A

Crystal Structure

Lattice constant a 331 pm

Electronic Structure

Electrons per shell 2, 8, 9, 2

Identifiers

CAS number 7440-20-2

Term symbol

InChI InChI=1S/Sc

InChI Key SIXSYDAISGFNSX-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge

Protons 21

Electrons 21

Charge Neutral

Configuration Sc: 3d¹ 4s²

[Ar] 3d¹ 4s²

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹ 4s²

Orbital diagram

↑↓

2/2

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑

1/10 1↑

Total electrons: 21 Unpaired: 1

Atomic model

Protons 21

Neutrons 24

Electrons 21

Mass number 45

Stability Stable

Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.

Schematic atomic model, not to scale.

Atomic Fingerprint

Emission / Absorption Spectrum

Emission Visible: 380–750 nm

Isotope Distribution

Mass number	Atomic mass (u)	Natural abundance	Half-life
45 Stable	44.95590828 ± 0.00000077	100.0000%	Stable

Measured

Phase / State

Solid 25 °C (298.15 K)

Reason: 1515.8 °C below melting point (1540.85 °C)

Melting point 1540.85 °C

Boiling point 2835.85 °C

Below melting by 1515.8 °C

0 K Current temperature: 25 °C 6000 K

Phase timeline

Schematic, not to scale

Solid

Liquid

Gas

Melting

Boiling

25°C

Solid

Liquid

Gas

Current

Phase transition points

Melting point Literature

1540.85 °C

Boiling point Literature

2835.85 °C

Current phase Calculated
Solid

Transition energies

Heat of fusion Literature

0.16582889 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature

3.256465 eV

Energy required to vaporize 1 mol at boiling point

Heat of sublimation Literature

3.923926 eV

Energy required to sublime 1 mol at sublimation point

Density

Reference density Literature

2990 kg/m³

At standard conditions

Current density Calculated

2990 kg/m³

At standard conditions

Atomic Spectra

Showing 10 of 21 Atomic Spectra. Sorted by ion charge (ascending).

Lines Holdings ?

Ion	Charge	Total lines	Transition probabilities	Level designations
Sc I	0	2198	260	1682
Sc II	+1	829	139	829
Sc III	+2	133	97	133
Sc IV	+3	408	4	408
Sc V	+4	456	16	456
Sc VI	+5	79	12	75
Sc VII	+6	70	37	70
Sc VIII	+7	75	48	75
Sc IX	+8	42	22	42
Sc X	+9	99	29	99

NIST Lines Holdings →

Levels Holdings ?

Ion	Charge	Levels
Sc I	0	478
Sc II	+1	169
Sc III	+2	44
Sc IV	+3	129
Sc V	+4	119
Sc VI	+5	40
Sc VII	+6	35
Sc VIII	+7	27
Sc IX	+8	27
Sc X	+9	68

NIST Levels Holdings →

21 Sc 44.955908

Scandium — Atomic Orbital Visualizer

[Ar]4s23d1

Energy levels 2 8 9 2

Oxidation states 0, +1, +2, +3

HOMO 3d n=3 · l=2 · m=-2

Scandium — Atomic Orbital Visualizer Preview

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21 Sc 44.955908

Scandium — Crystal Structure Visualizer

Primitive Hexagonal · Pearson hP2

Experimental

Pearson hP2

Coord. № 12

Packing 75.056%

Scandium — Crystal Structure Visualizer Preview

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Ionic Radii

Charge	Coordination	Spin	Radius
+3	6	N/A	74.5 pm
+3	8	N/A	87 pm

Compounds

44.956 u

45.955 u

46.952 u

43.959 u

48.950 u

42.961 u

47.952 u

Sc+3

44.956 u

Isotopes (1)

	Mass number	Atomic mass (u)	Natural abundance	Half-life	Decay mode
	45 Stable	44.95590828 ± 0.00000077	100.0000%	Stable	stable

45 Stable

Atomic mass (u) 44.95590828 ± 0.00000077

Natural abundance 100.0000%

Half-life Stable

Decay mode

stable

Spectral Lines

Showing 50 of 946 Spectral Lines. Only spectral lines with measured intensity are shown by default.

Wavelength (nm)	Intensity	Ion stage	Type	Transition	Accuracy	Source
683.5026 nm	640	Sc I	emission	3d2.(3P).4s 2P → 3d2.(3P).4p 2S*	Measured	NIST
681.9491 nm	485	Sc I	emission	3d.4s.(1D).4p 2F* → 3d.4s.(3D).5s 2D	Measured	NIST
673.7872 nm	465	Sc I	emission	3d.4s.(3D).4p 2F* → 3d.4s.(3D).4d 2G	Measured	NIST
673.945 nm	360	Sc I	emission	3d.4s.(3D).4p 2F* → 3d.4s.(3D).4d 2G	Measured	NIST
681.7117 nm	345	Sc I	emission	3d2.(3P).4s 2P → 3d2.(3P).4p 2S*	Measured	NIST
682.9509 nm	335	Sc I	emission	3d.4s.(1D).4p 2F* → 3d.4s.(3D).5s 2D	Measured	NIST
406.8661 nm	100	Sc III	emission	3p6.4d 2D → 3p6.4f 2F*	Measured	NIST
744.9141 nm	90	Sc III	emission	3p6.5s 2S → 3p6.5p 2P*	Measured	NIST
406.121 nm	80	Sc III	emission	3p6.4d 2D → 3p6.4f 2F*	Measured	NIST
625.6013 nm	80	Sc III	emission	3p6.4d 2D → 3p6.5p 2P*	Measured	NIST
503.2072 nm	60	Sc III	emission	3p6.5p 2P* → 3p6.5d 2D	Measured	NIST
630.7603 nm	60	Sc III	emission	3p6.4d 2D → 3p6.5p 2P*	Measured	NIST
499.2886 nm	50	Sc III	emission	3p6.5p 2P* → 3p6.5d 2D	Measured	NIST
652.5571 nm	40	Sc I	emission	3d.4s.(3D).4p 2D* → 3d.4s.(3D).4d 2D	Measured	NIST
671.4599 nm	40	Sc I	emission	3d.4s.(3D).4p 2D* → 3d.4s.(3D).4d 4D	Measured	NIST
655.7842 nm	35	Sc I	emission	3d.4s.(1D).4p 2F* → 3d3 2D2	Measured	NIST
688.5119 nm	27	Sc I	emission	3d2.(3F).4p 4F* → 3d2.(3F).4d 4G	Measured	NIST
716.9083 nm	27	Sc I	emission	3d.4s.(3D).4p 2D* → 3d.4s.(3D).4d 2F	Measured	NIST
688.1012 nm	26	Sc I	emission	3d2.(3F).4p 4F* → 3d2.(3F).4d 4G	Measured	NIST
662.0207 nm	21	Sc I	emission	3d.4s.(3D).4p 2F* → 3d3 2F	Measured	NIST
713.8107 nm	19	Sc I	emission	3d.4s.(3D).4p 2D* → 3d.4s.(3D).4d 2F	Measured	NIST
467.0407 nm	18	Sc II	emission	3p6.3d2 1D → 3p6.3d.4p 1F*	Measured	NIST
673.0754 nm	18	Sc I	emission	3d2.(3F).4p 4D* → 4P	Measured	NIST
687.7343 nm	18	Sc I	emission	3d2.(3F).4p 4F* → 3d2.(3F).4d 4G	Measured	NIST
431.4083 nm	17	Sc II	emission	3p6.3d2 3F → 3p6.3d.4p 3D*	Measured	NIST
503.1021 nm	17	Sc II	emission	3p6.3d2 1D → 3p6.3d.4p 1P*	Measured	NIST
680.4611 nm	17	Sc I	emission	3d2.(3F).4p 4F* → 3d2.(3F).4d 4D	Measured	NIST
437.4457 nm	16	Sc II	emission	3p6.3d2 3F → 3p6.3d.4p 3F*	Measured	NIST
523.9813 nm	16	Sc II	emission	3p6.4s2 1S → 3p6.3d.4p 1P*	Measured	NIST
552.679 nm	16	Sc II	emission	3p6.3d2 1G → 3p6.3d.4p 1F*	Measured	NIST
430.5714 nm	15	Sc II	emission	3p6.3d2 3F → 3p6.3d.4p 3D*	Measured	NIST
432.0732 nm	15	Sc II	emission	3p6.3d2 3F → 3p6.3d.4p 3D*	Measured	NIST
478.0863 nm	15	Sc III	emission	3p6.5p 2P* → 3p6.6s 2S	Measured	NIST
565.7896 nm	15	Sc II	emission	3p6.3d2 3P → 3p6.3d.4p 3P*	Measured	NIST
624.5637 nm	15	Sc II	emission	3p6.3d2 3P → 3p6.3d.4p 3D*	Measured	NIST
577.1538 nm	14	Sc IV	emission	3s2.3p5.(2P<3/2>).5s 2[3/2] → 3s2.3p5.(2P*<3/2>).5p 2[5/2]	Measured	NIST
637.0486 nm	14	Sc II	emission	3p6.3d.4d 1F → 3p6.3d.4f 1G*	Measured	NIST
660.4601 nm	14	Sc II	emission	3p6.3d2 1D → 3p6.3d.4p 1D*	Measured	NIST
680.3677 nm	14	Sc I	emission	3d.4s.(3D).4p 2F* → 3d.4s.(3D).4d 2G	Measured	NIST
725.7589 nm	14	Sc I	emission	3d2.(3F).4p 4F* → 3d.(2D).4p2.(3P) 4F	Measured	NIST
401.4484 nm	13	Sc II	emission	3p6.3d.4s 1D → 3p6.3d.4p 3F*	Measured	NIST
429.4767 nm	13	Sc II	emission	3p6.3d2 3F → 3p6.3d.4p 3D*	Measured	NIST
432.4996 nm	13	Sc II	emission	3p6.3d2 3F → 3p6.3d.4p 3D*	Measured	NIST
564.1001 nm	13	Sc II	emission	3p6.3d2 3P → 3p6.3d.4p 3P*	Measured	NIST
565.8361 nm	13	Sc II	emission	3p6.3d2 3P → 3p6.3d.4p 3P*	Measured	NIST
566.9042 nm	13	Sc II	emission	3p6.3d2 3P → 3p6.3d.4p 3P*	Measured	NIST
687.4193 nm	13	Sc I	emission	3d2.(3F).4p 4F* → 3d2.(3F).4d 4G	Measured	NIST
385.9595 nm	12	Sc II	emission	3p6.3d.4p 1F* → 3p6.3d.5s 1D	Measured	NIST
424.6822 nm	12	Sc II	emission	3p6.3d.4s 1D → 3p6.3d.4p 1D*	Measured	NIST
435.4598 nm	12	Sc II	emission	3p6.3d2 3F → 3p6.3d.4p 3F*	Measured	NIST

Extended Properties

Covalent Radii (Extended)

Covalent radius (Pyykkö)

Covalent radius (Pyykkö, double)

Covalent radius (Pyykkö, triple)

Van der Waals Radii

Batsanov

Alvarez

UFF

MM3

Atomic & Metallic Radii

Atomic radius (Rahm)

Metallic radius (C12)

Numbering Scales

Mendeleev

Pettifor

Glawe

Electronegativity Scales

Ghosh

Miedema

Gunnarsson–Lundqvist

Robles–Bartolotti

Polarizability & Dispersion

Dipole polarizability

Dipole polarizability (unc.)

C₆

C₆ (Gould–Bučko)

Chemical Affinity

Proton affinity

Gas basicity

Miedema Parameters

Miedema molar volume

Miedema electron density

Supply Risk & Economics

Production concentration

Relative supply risk

Reserve distribution

Political stability (top producer)

Political stability (top reserve)

Phase Transitions & Allotropes

Melting point	1814.15 K
Boiling point	3109.15 K

Oxidation State Categories

+3 main

+1 extended

+2 extended

0 extended

Advanced Reference Data

Screening Constants (7)

n	Orbital	σ
1	s	0.5434
2	p	3.9454
2	s	6.4264
3	d	13.8801
3	p	11.5938
3	s	10.6602
4	s	16.3676

Crystal Radii Detail (2)

Charge	CN	Spin	r_crystal (pm)	Origin
3	VI		88.5	from r^3 vs V plots,
3	VIII		101	from r^3 vs V plots,

Isotope Decay Modes (52)

Isotope	Mode	Intensity
35	p	—
36	p	—
37	p	—
38	p	—
39	p	100%
40	B+	100%
40	B+p	0.4%
40	B+A	0%
41	B+	100%
42	B+	100%

X‑ray Scattering Factors (598)

Energy (eV)	f₁	f₂
10	—	1.06978
10.1617	—	1.07987
10.3261	—	1.09005
10.4931	—	1.10033
10.6628	—	1.11071
10.8353	—	1.12118
11.0105	—	1.13176
11.1886	—	1.14243
11.3696	—	1.15321
11.5535	—	1.16408

Additional Data

Estimated Crustal Abundance

The estimated element abundance in the earth's crust.

2.2×101 milligrams per kilogram

References (1)

[5] Scandium https://education.jlab.org/itselemental/ele021.html

Estimated Oceanic Abundance

The estimated element abundance in the earth's oceans.

6×10-7 milligrams per liter

References (1)

[5] Scandium https://education.jlab.org/itselemental/ele021.html

Sources

Sources of this element.

Scandium is apparently much more abundant (the 23rd most) in the sun and certain stars than on earth (the 50th most abundant). It is widely distributed on earth, occurring in very minute quantities in over 800 mineral species. The blue color of beryl (aquamarine variety) is said to be due to scandium. It occurs as a principal component in the rare mineral thortveitite, found in Scandinavia and Malagasy. It is also found in the residues remaining after the extraction of tungsten from Zinnwald wolframite, and in wiikite and bazzite.

Most scandium is presently being recovered from thortveitite or is extracted as a by-product from uranium mill tailings. Metallic scandium was first prepared in 1937 by Fischer, Brunger, and Grienelaus who electrolyzed a eutectic melt of potassium, lithium, and scandium chlorides at 700 to 800°C. Tungsten wire and a pool of molten zinc served as the electrodes in a graphite crucible. Pure scandium is now produced by reducing scandium fluoride with calcium metal.

The production of the first pound of 99% pure scandium metal was announced in 1960.

References (1)

[6] Scandium https://periodic.lanl.gov/21.shtml

References

(9)

1 PubChem

Data deposited in or computed by PubChem

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2 Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)

The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.

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3 IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)

Scandium

Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.

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4 IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.

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License note: 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.

5 Jefferson Lab, U.S. Department of Energy

Scandium

Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/

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License note: Please see citation and linking information: https://education.jlab.org/faq/index.html

6 Los Alamos National Laboratory, U.S. Department of Energy

Scandium

The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.

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7 NIST Physical Measurement Laboratory

Scandium

The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database

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8 PubChem Elements

Scandium

This section provides all form of data related to element Scandium.

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9 PubChem Elements

Scandium

The element property data was retrieved from publications.

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Last updated: May 1, 2026

Data verified: May 12, 2026

Content is reviewed against latest scientific data.