Praseodymium (Pr): Bohr Model, Protons, Neutrons & Electrons
Praseodymium is element number 59, a lanthanide in the f-block (the lanthanide row drawn below the table), period 6. Its atom has 59 protons, 82 neutrons and 59 electrons arranged in 6 shells: 2, 8, 18, 21, 8, 2.
- 59 protons
- 82 neutrons
- 59 electrons
Protons, neutrons and electrons in praseodymium
The atomic number of praseodymium is 59, so every praseodymium atom has 59 protons. A neutral atom has the same number of electrons, 59. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For praseodymium-141, that is 141 − 59 = 82 neutrons.
How to draw the Bohr model of praseodymium
- Draw the nucleus and write 59 p⁺ and 82 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 21 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 + 21 + 8 + 2 = 59 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, 21, 8, 2) is the one to draw.
Electron configuration
The electron configuration of praseodymium is [Xe] 6s² 4f³. As a lanthanide it fills an inner f-subshell, and its common ion is Pr³⁺.
Key facts about praseodymium
| Symbol | Pr |
|---|---|
| Atomic number | 59 |
| Relative atomic mass | 140.91 |
| Group · period · block | f-block · period 6 |
| Type | Lanthanide |
| State at 25 °C | solid |
| Electron shells | 2, 8, 18, 21, 8, 2 |
| Electron configuration | [Xe] 6s² 4f³ |
| Valence electrons | varies (outer shell: 2) |
| Common ion | Pr³⁺ |
| Electronegativity (Pauling) | 1.13 |
| First ionisation energy | 5.47 eV (528 kJ/mol) |
| Atomic radius (empirical) | 185 pm |
Where praseodymium sits on the periodic table
Frequently asked questions
How many protons, neutrons and electrons does praseodymium have?
Praseodymium has 59 protons and 59 electrons (atomic number 59). Its most common isotope, praseodymium-141, has 141 − 59 = 82 neutrons.
What is the electron configuration of praseodymium?
[Xe] 6s² 4f³. In shells that is 2, 8, 18, 21, 8, 2.
How many valence electrons does praseodymium have?
Praseodymium is a lanthanide, so its valence electrons are spread over two shells; its outermost shell holds 2.
Where is praseodymium 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.
