Praseodymium (Pr)
Praseodymium is element 59, a lanthanide in the lanthanide series (period 6). A neutral atom has 59 protons, 82 neutrons and 59 electrons, 2 of them valence electrons.
Lanthanide- Atomic number
- 59
- Atomic mass
- 140.91 u
- Valence electrons
- 2*
- Protons · neutrons
- 59 · 82
- Electrons per shell
- 2, 8, 18, 21, 8, 2
- At room temperature
- solid
Bohr model of praseodymium
The Bohr model draws praseodymium as a nucleus of 59 protons and 82 neutrons, with its 59 electrons on 6 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 21 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 praseodymium
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f³
Short form (noble gas notation): [Xe] 6s² 4f³. The [Xe] stands for the electrons of xenon, the noble gas before it.
How many valence electrons does praseodymium have?
Praseodymium has 2 valence electrons.
Praseodymium 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 | 59 | equal to the atomic number |
|---|---|---|
| Electrons | 59 | equal to the protons in a neutral atom |
| Neutrons | 82 | mass number 141 − 59 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.
Praseodymium properties
| Symbol | Pr |
|---|---|
| Category | Lanthanide |
| Group · period · block | — · 6 · f |
| Atomic mass | 140.91 u |
| State at 25 °C | solid |
| Melting point | 1,204 K (931 °C, 1,710 °F) |
| Boiling point | 3,793 K (3,520 °C, 6,370 °F) |
| Density | 6.77 g/cm³ |
| Electronegativity (Pauling) | 1.13 |
| Atomic radius | 239 pm |
| First ionization energy | 5.464 eV |
| Electron affinity | — |
| Oxidation states | +3 |
| Common ion charge | +3 |
| Discovered | 1885 by Carl Auer von Welsbach |
Where praseodymium sits on the periodic table
Lanthanides: Lanthanum, Cerium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium.
Questions about praseodymium
How many valence electrons does praseodymium have?
Praseodymium has 2 valence electrons in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does praseodymium have?
A neutral praseodymium atom has 59 protons and 59 electrons. Its most common form has about 82 neutrons (mass number 141 − 59 protons).
What is the electron configuration of praseodymium?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f³, written in short form as [Xe] 6s² 4f³.
What does the Bohr model of praseodymium look like?
A nucleus of 59 protons and 82 neutrons, circled by 6 electron shells holding 2, 8, 18, 21, 8, 2 electrons.
What is the atomic number of praseodymium?
59. The atomic number is the number of protons in the nucleus, and it is what makes an atom praseodymium.