59PrPraseodymium140.907662[Xe] 4f³ 6s²
lanthanide

Praseodymium

Praseodymium is a chemical element with symbol Pr and atomic number 59. Praseodymium is a soft, silvery, malleable and ductile metal in the lanthanide group. It is valued for its magnetic, electrical, chemical, and optical properties.

Properties

At a glance

Atomic number
59
Atomic mass
140.907662 u
Phase
Solid
Density
6.77 g/cm³
Melting point
1,208 K
Boiling point
3,403 K
First ionization energy
527.8 kJ/mol (estimated)
Electronegativity
1.13
Electron affinity
93 kJ/mol
Molar heat capacity
27.2 J/(mol·K)
Period
6
Appearance
grayish white

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

Electronic structure

Praseodymium’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…

59 protons82 neutrons

Praseodymium-141: 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, praseodymium 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

Pr

PrNeutral atom · no charge

A neutral praseodymium atom. Removing its first electron takes 528 kJ/mol.

Praseodymium’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 2× 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). Praseodymium’s first electron takes about 5.5 eV.
1001,00010,000100,0001,000,00010,000,000Shell 5Shell 4Shell 3Shell 2×2×1.1×1.7×2.3×4.11510152025303540455055
Show the values as a table
ElectronShellEnergy (kJ/mol)× previousValue
16528–Estimated
261,0261.9Estimated
352,0862Measured
453,7611.8Estimated
555,5511.5Estimated
657,9121.4Calculated
759,3591.2Calculated
8510,8061.2Calculated
9512,6401.2Calculated
10514,2801.1Calculated
11415,6311.1Calculated
12418,9111.2Calculated
13420,9391.1Estimated
14433,7701.6Calculated
15436,4711.1Calculated
16439,7521.1Calculated
17442,9361.1Calculated
18446,1201.1Calculated
19449,7861.1Calculated
20453,4531.1Calculated
21456,9261.1Calculated
22460,4961.1Calculated
23463,9701.1Calculated
24477,4781.2Calculated
25481,0481Calculated
26484,9071Calculated
27488,7671Calculated
28495,0381.1Calculated
29499,1871Calculated
304108,4501.1Calculated
314112,8781Estimated
323194,8041.7Calculated
333203,3911Calculated
343212,4611Calculated
353222,3021Calculated
363231,5651Calculated
373241,3101Calculated
383253,5631.1Calculated
393263,3081Calculated
403273,8251Calculated
413283,7631Calculated
423311,3581.1Calculated
433320,2351Calculated
443329,8831Calculated
453338,8561Calculated
463359,7941.1Calculated
473369,7321Calculated
483388,8361.1Calculated
493398,4841Calculated
502904,8392.3Calculated
512929,3471Calculated
522956,4591Calculated
532981,7381Calculated
5421,057,3831.1Calculated
5521,086,6181Calculated
5621,123,1861Calculated
5721,147,7791Calculated
5814,686,4584.1Calculated
5914,797,4861Calculated

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?

PraseodymiumOther lanthanidesOther elements

Density

6.77 g/cm³46th lowest of 99

Pr

Melting point

1,208 K48th lowest of 96

Pr

Boiling point

3,403 K27th highest of 97

Pr

Electronegativity

1.1318th lowest of 96

Pr

First ionization energy

528 kJ/mol11th lowest of 99

Pr

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.