Chemical Formula
Pr
Background
In 1841, Carl Mosander separated two 'elements' ,didymium and lanthanum, from cerium. Although didymium was considered as an element for several years, scientists suspected didymium was in fact a mixture of elements. There suspicions were confirmed when Bohuslav Brauner from Prague proved that the atomic spectrum of didymium was not similar to that of a pure metal. However, Brauner failed to separate the elements of didymium. Following this, Carl Auer von Welsbach, an Austrian chemist succeeded in splitting didymium into oxides of neodymium and praseodymium in 1885. Praseodymium was named after the Greek words 'prasios didymos’ which means 'green twin' as it behaves like lanthanum.
Basic Information
| Name |
Praseodymium |
| Symbol |
Pr |
| Atomic number |
59 |
| Atomic weight |
140.9 amu |
| Standard state |
Solid at 298 K |
| CAS Registry ID |
7440-10-0 |
| Group name |
Lanthanoid |
| Period in periodic table |
6 |
| Block in periodic table |
f-block |
| Color |
Silvery white, yellowish tinge |
| Classification |
Metallic |
| Melting point |
1204 K (931°C or 1708°F) |
| Boiling point |
3793 K (3520°C or 6368°F) |
| Density |
6.77 g/cm3 |
| Phase at room temperature |
Solid |
Occurrence
Praseodymium has a concentration fo about 3.5 to 5.5 ppm inthe Earth's crust. It can be found in mineral ores like monazite and bastnasite as well.
Praseodymium - Periodic Table of Videos
Isotopes
Around 32 isotopes of praseodymium have been observed so far, which include 121Pr to 154Pr. Praseodymium has only one naturally- occurring stable isotope, 141Pr.
Production
Praseodymium can be prepared by reducing the mixture of anhydrous chloride and fluoride with calcium. Commercially, it is recovered from monazite sand and bastnasite by extraction processes and ion exchange techniques.
Health Aspects
Like all other rare metals, the toxicity of praseodymium varies from low to moderate. Soluble praseodymium salts are mildly toxic and insoluble salts are non toxic. Some of the health hazards of praseodymium include the following:
- Skin and eye irritation
- Lung embolisms
- Liver diseases
Key Properties
The key properties of praseodymium include the following:
- It is a soft, silvery, lustrous, metallic, ductile metal
- It readily reacts with water to form hydroxides and air to form oxides
- It generally exists in its trivalent state
Applications
Some of the applications of praseodymium are listed below:
- It is used in high-intensity permanent magnets that are suitable for electric generators , motors of wind turbines and hybrid cars
- It is used for the manufacture of special yellow glass goggles of glass welders and blowers
- It is used as an alloying agent employed for manufacturing high-strength metals used in high-strength metal
- It is used in high-intensity carbon arc lights for floodlighting and film industry applications.
References
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