67HoHolmium164.930332[Xe] 4f¹¹ 6s²
lanthanide

Holmium

Holmium is a chemical element with symbol Ho and atomic number 67. Part of the lanthanide series, holmium is a rare earth element. Holmium was discovered by Swedish chemist Per Theodor Cleve.

Properties

At a glance

Atomic number
67
Atomic mass
164.930332 u
Phase
Solid
Density
8.79 g/cm³
Melting point
1,734 K
Boiling point
2,873 K
First ionization energy
581 kJ/mol
Electronegativity
1.23
Electron affinity
32.61 kJ/mol
Molar heat capacity
27.15 J/(mol·K)
Period
6
Appearance
silvery white

Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.

Electronic structure

Holmium’s orbitals use a hydrogen-like approximation. Every orbital of each visible subshell is shown: in Shapes as the surface holding half its probability, with light and dark shades for opposite signs of the wavefunction; in Cloud as dots where its electrons are likely to be. Sizes are stepped by shell, like the Shell model.

Electrons by shell
Electron configuration

54 is the [Xe] core total across five shells.

Preparing the orbital view…

67 protons98 neutrons

Holmium-165: its most common form in nature, or its longest-lived if it has none. The nucleus is drawn far too big: it’s about 100,000 times smaller than the atom.

States of matter

Turn up the heat

298 KK stands for kelvin, the temperature scale used in science. It starts at absolute zero (0 K), the coldest temperature possible, so it has no negative numbers and no degree sign.

A step of 1 K is the same size as 1 °C, so the two scales are always 273.15 apart. Fahrenheit is different: its degrees are smaller and it starts elsewhere, so water freezes at 273.15 K, 0 °C and 32 °F.25 °C · 77 °FSolid

At this temperature, holmium is a solid.

At normal atmospheric pressure (1 atm). The temperature scale is logarithmic. The particle box is schematic: real samples hold vastly more atoms, and spacing and speeds are not to scale.

Ionization energy

Pull the electrons off

Ho

HoNeutral atom · no charge

A neutral holmium atom. Removing its first electron takes 581 kJ/mol.

Holmium’s outer shell holds 2 electrons. Electron 3 is the first from an inner shell: it sits closer to the nucleus with less shielding, so removing it takes 1.9× as much energy as the one before. Each dashed line on the chart marks another jump, into a shell even closer to the nucleus.

Shell 1Shell 2Shell 3Shell 4Shell 5Shell 6MeasuredEstimated or calculatedEnergy in kJ/molkJ/mol (kilojoules per mole) is the energy to remove that electron from every atom in a mole of them: about 602 sextillion (6.02 × 10²³) atoms. For a single atom, divide by 96.485 to get electronvolts (eV). Holmium’s first electron takes about 6 eV.
1001,00010,000100,0001,000,00010,000,000Shell 5Shell 4Shell 3Shell 2×1.9×1.1×1.7×2.2×4.115101520253035404550556065
Show the values as a table
ElectronShellEnergy (kJ/mol)× previousValue
16581–Measured
261,1372Estimated
352,1991.9Estimated
454,1031.9Estimated
556,1651.5Estimated
659,1661.5Calculated
7510,8061.2Calculated
8512,4471.2Calculated
9514,9551.2Calculated
10516,6921.1Calculated
11419,0081.1Calculated
12422,0951.2Calculated
13425,3761.1Calculated
14427,4021.1Calculated
15429,4281.1Calculated
16432,8051.1Calculated
17435,9891.1Calculated
18439,3661.1Calculated
19442,5501.1Calculated
20445,8311.1Calculated
21449,2081.1Calculated
22468,9871.4Calculated
23472,8461.1Calculated
24476,8991.1Calculated
25481,2411.1Calculated
26485,3901.1Calculated
27489,6351Calculated
28495,0381.1Calculated
29499,2831Calculated
304103,9151Calculated
314108,2571Calculated
324125,4311.2Calculated
334129,8691Calculated
344134,5971Calculated
354139,2281Calculated
364149,0701.1Calculated
374154,1841Calculated
384165,8581.1Calculated
394171,1261Estimated
403291,1931.7Calculated
413301,5171Calculated
423312,4201Calculated
433324,0941Calculated
443335,3831Calculated
453346,5751Calculated
463362,7851Calculated
473374,3631Calculated
483386,8101Calculated
493398,5811Calculated
503431,1931.1Calculated
513441,5171Calculated
523452,8061Calculated
533463,3231Calculated
543495,4521.1Calculated
553507,3201Calculated
563530,0901Calculated
573541,3791Calculated
5821,205,5842.2Calculated
5921,234,0471Calculated
6021,265,5021Calculated
6121,294,5441Calculated
6221,412,4491.1Calculated
6321,447,0871Calculated
6421,490,5051Calculated
6521,519,2361Calculated
6616,153,1034.1Calculated
6716,284,7781Calculated

Successive ionization energies of gas-phase atoms and ions from the NIST Atomic Spectra Database. Solid bars are measured; hatched bars were estimated from nearby measurements or calculated from quantum theory, as is usual for highly charged ions. Electrons are taken from the outermost shell first, a simplification: electrons in different subshells of the same shell also differ in energy. On the log scale each gridline is 10 times the one below.

Compared with other elements

How does it compare?

HolmiumOther lanthanidesOther elements

Density

8.79 g/cm³37th highest of 99

Ho

Melting point

1,734 K28th highest of 96

Ho

Boiling point

2,873 K46th highest of 97

Ho

Electronegativity

1.2325th lowest of 96

Ho

First ionization energy

581 kJ/mol27th lowest of 99

Ho

Elements 1–99 from the reference data; heavier elements are left out because only a few atoms have ever been made, so their bulk properties are predictions. First ionization energies come from NIST. Density uses a logarithmic scale, because gases are around a thousand times less dense than solids; gas densities are at 0 °C and 1 atm. Melting and boiling points are at normal pressure. Everyday temperatures and light sources in the pictures are approximate. Hover over a dot to see the element, or click it to compare.

Keep exploring

Explore the stories, imagery, and reference data in more depth. Properties with no value in the reference are marked unavailable.