Holmium (Ho): Bohr Model, Protons, Neutrons & Electrons
Holmium is element number 67, a lanthanide in the f-block (the lanthanide row drawn below the table), period 6. Its atom has 67 protons, 98 neutrons and 67 electrons arranged in 6 shells: 2, 8, 18, 29, 8, 2.
Protons, neutrons and electrons in holmium
The atomic number of holmium is 67, so every holmium atom has 67 protons. A neutral atom has the same number of electrons, 67. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For holmium-165, that is 165 − 67 = 98 neutrons.
How to draw the Bohr model of holmium
- Draw the nucleus and write 67 p⁺ and 98 n⁰ inside it.
- Draw the first shell and put 2 electrons on it (the first shell holds at most 2).
- Draw the second shell and put 8 electrons on it.
- Draw the third shell and put 18 electrons on it.
- Draw the fourth shell and put 29 electrons on it.
- Draw the fifth shell and put 8 electrons on it.
- Draw the sixth shell and put 2 electrons on it.
- Check: 2 + 8 + 18 + 29 + 8 + 2 = 67 electrons, the same as the number of protons.
From potassium onwards the shells don’t simply fill as 2, 8, 8: the fourth shell starts before the third is full, so the real arrangement above (2, 8, 18, 29, 8, 2) is the one to draw.
Electron configuration
The electron configuration of holmium is [Xe] 6s² 4f¹¹. As a lanthanide it fills an inner f-subshell, and its common ion is Ho³⁺.
Key facts about holmium
| Symbol | Ho |
|---|---|
| Atomic number | 67 |
| Relative atomic mass | 164.93 |
| Group · period · block | f-block · period 6 |
| Type | Lanthanide |
| State at 25 °C | solid |
| Electron shells | 2, 8, 18, 29, 8, 2 |
| Electron configuration | [Xe] 6s² 4f¹¹ |
| Valence electrons | varies (outer shell: 2) |
| Common ion | Ho³⁺ |
| Electronegativity (Pauling) | 1.23 |
| First ionisation energy | 6.02 eV (581 kJ/mol) |
| Atomic radius (empirical) | 175 pm |
Where holmium sits on the periodic table
Frequently asked questions
How many protons, neutrons and electrons does holmium have?
Holmium has 67 protons and 67 electrons (atomic number 67). Its most common isotope, holmium-165, has 165 − 67 = 98 neutrons.
What is the electron configuration of holmium?
[Xe] 6s² 4f¹¹. In shells that is 2, 8, 18, 29, 8, 2.
How many valence electrons does holmium have?
Holmium is a lanthanide, so its valence electrons are spread over two shells; its outermost shell holds 2.
Where is holmium on the periodic table?
In the f-block (the lanthanide row drawn below the table), period 6, in the f-block. It is a lanthanide.
