Holmium (Ho)
Holmium is element 67, a lanthanide in the lanthanide series (period 6). A neutral atom has 67 protons, 98 neutrons and 67 electrons, 2 of them valence electrons.
Lanthanide- Atomic number
- 67
- Atomic mass
- 164.93 u
- Valence electrons
- 2*
- Protons · neutrons
- 67 · 98
- Electrons per shell
- 2, 8, 18, 29, 8, 2
- At room temperature
- solid
Bohr model of holmium
The Bohr model draws holmium as a nucleus of 67 protons and 98 neutrons, with its 67 electrons on 6 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 29 in shell 4, 8 in shell 5, 2 in shell 6. Press Build the atom to watch the shells fill from the inside out. The outer ring (the P shell) is dashed: the electrons there are the ones that take part in chemistry.
Real electrons don't travel in neat circles. They live in fuzzy orbitals, shown below, but the Bohr picture is the quickest way to count shells and valence electrons.
Electron configuration of holmium
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹¹
Short form (noble gas notation): [Xe] 6s² 4f¹¹. The [Xe] stands for the electrons of xenon, the noble gas before it.
How many valence electrons does holmium have?
Holmium has 2 valence electrons.
Holmium is a lanthanide, so its valence electrons are less clear-cut than for main-group elements. It has 2 electrons in its outermost shell (shell 6), and electrons in its inner f and d subshell can also take part in bonding.
Protons, neutrons and electrons
| Protons | 67 | equal to the atomic number |
|---|---|---|
| Electrons | 67 | equal to the protons in a neutral atom |
| Neutrons | 98 | mass number 165 − 67 protons |
Atoms of the same element can have different numbers of neutrons (isotopes). The count above uses the rounded atomic mass, the way it's taught in class.
Holmium properties
| Symbol | Ho |
|---|---|
| Category | Lanthanide |
| Group · period · block | — · 6 · f |
| Atomic mass | 164.93 u |
| State at 25 °C | solid |
| Melting point | 1,747 K (1,470 °C, 2,680 °F) |
| Boiling point | 2,973 K (2,700 °C, 4,890 °F) |
| Density | 8.8 g/cm³ |
| Electronegativity (Pauling) | 1.23 |
| Atomic radius | 216 pm |
| First ionization energy | 6.022 eV |
| Electron affinity | — |
| Oxidation states | +3 |
| Common ion charge | +3 |
| Discovered | 1878 by Marc Delafontaine |
Where holmium sits on the periodic table
Lanthanides: Lanthanum, Cerium, Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium.
Questions about holmium
How many valence electrons does holmium have?
Holmium has 2 valence electrons in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does holmium have?
A neutral holmium atom has 67 protons and 67 electrons. Its most common form has about 98 neutrons (mass number 165 − 67 protons).
What is the electron configuration of holmium?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹¹, written in short form as [Xe] 6s² 4f¹¹.
What does the Bohr model of holmium look like?
A nucleus of 67 protons and 98 neutrons, circled by 6 electron shells holding 2, 8, 18, 29, 8, 2 electrons.
What is the atomic number of holmium?
67. The atomic number is the number of protons in the nucleus, and it is what makes an atom holmium.