Promethium Element
The Promethium element is represented by the symbol Pm. Promethium is a lanthanide and a rare earth metal. All the isotopes of promethium are radioactive in nature. Promethium metal emits beta radiation. As it is a rare metal, so its chemical and physical characteristics are not well known. Promethium salts have a pink or red colour that gives a pale blue-green glow to the ambient air. Promethium metal was discovered by Mariinsky in 1945.
Electronic configuration- [Xe]4f56s2
The atomic number of promethium- 61
The atomic mass of promethium- 145gmol-1
Physical Properties of Promethium
Promethium is the f-block element that belongs to the group lanthanides and period 6. It is solid at 20°C.
Melting point- 1042°C, 1908°F, 1315 K
Boiling point- 3000°C, 5432°F, 3273 K
The density of promethium- 7.26
Chemical Properties of Promethium
Chemically, promethium is a lanthanide, when mixed with other elements, forms salts. It shows only one stable state of oxidation of +3.
Since traces of the element are extremely scarce in nature, the element is typically synthesized to produce promethium-147 by bombarding enriched uranium with thermal neutrons.
Promethium salts have pink or red colour with a pale blue-green light that colours the surrounding air.
Promethium Uses
Most promethium is used only for research purposes except for promethium-147, which can be found outside laboratories. It is obtained in milligram quantities as oxide or chloride. This isotope does not emit gamma rays, and its radiation has a relatively small depth of penetration in the matter and a relatively long half-life.
Promethium used as a pacemaker. A luminous paint containing a phosphor that absorbs the beta radiation emitted by promethium-147 and emits light is used by some signal lights.
In atomic batteries, by sandwiching a small promethium source between two semiconductor plates, the beta particles emitted by promethium-147 are converted into electric current. These batteries have a lifetime of approximately five years. Promethium is often used to measure the thickness of materials by measuring the amount of radiation from a promethium source that passes through the sample. Potential applications can be made for portable X-ray sources and as auxiliary heat or power sources for space probes and satellites.
Precautions
The promethium does not have a biological function. During its beta decay, Promethium-147 will emit gamma rays that are harmful to all life forms. encounters with small amounts of promethium-147 are not dangerous If certain precautions are taken. In general, gloves, footwear covers, safety glasses, and an outer layer of protective clothing that can be quickly removed should be used.
Promethium mainly affects bone tissue. It is not risky to have a sealed promethium-147. If the packaging is impaired, however, then promethium becomes harmful for the environment and humans. The polluted area should be cleaned with water and soap if radioactive contamination is detected.
Did You Know?
There in the Andromeda galaxy is the peculiar star HR 465, which contains a lot of Promethium. It is very radioactive and rare, very little has been studied: it is not well described in its chemical and physical properties.
FAQs on Promethium
1. What is Promethium and what is its atomic number?
Promethium, represented by the symbol Pm, is a chemical element with the atomic number 61. It belongs to the lanthanide series of the periodic table, also known as rare earth metals. A key characteristic of Promethium is that all of its isotopes are radioactive, meaning it has no stable form.
2. What is the electronic configuration of Promethium?
The ground-state electronic configuration for a Promethium (Pm) atom is [Xe] 4f⁵ 6s². This configuration places it in the f-block of the periodic table, and its chemical properties are largely influenced by the electrons in its 4f and 6s orbitals.
3. Is Promethium a naturally occurring element?
Promethium is extremely rare in nature and is not found in significant quantities in the Earth's crust. While minuscule traces can be formed through the spontaneous fission of uranium, it is primarily considered a synthetic element for all practical purposes. It is commercially produced by bombarding neodymium with neutrons inside a nuclear reactor.
4. What are the most important uses of Promethium?
The isotope Promethium-147 is the most useful due to its specific radioactive properties. Its main applications include:
- Atomic Batteries: It is used in long-life batteries that power devices like pacemakers and guided missiles, converting beta radiation into electricity.
- Luminous Paints: It serves as a light source for luminous dials and signs that glow without external energy.
- Thickness Gauges: In industrial settings, it is used to measure the thickness of materials by detecting the amount of radiation that passes through them.
5. What are the key physical and chemical properties of Promethium?
Promethium is a metallic element with several distinct properties:
- Oxidation State: Its only stable oxidation state in compounds is +3.
- Appearance: Promethium salts typically have a pink or red colour.
- Density: Its density is 7.26 g/cm³.
- Melting Point: It melts at 1042°C (1315 K).
- Boiling Point: It boils at 3000°C (3273 K).
6. Is Promethium harmful to humans?
Yes, Promethium is harmful due to its radioactivity. The isotope Promethium-147 emits beta radiation, which can damage living tissue. While a properly sealed source poses little risk, if the element is inhaled or ingested, it can accumulate in the bone tissue and pose a serious health hazard. Therefore, it must be handled with special precautions, including protective clothing and gloves.
7. Why is Promethium the only lanthanide that has no stable isotopes?
Promethium's lack of stable isotopes is a consequence of its nuclear structure. As an element with an odd atomic number (61), it is inherently less likely to have stable isotopes according to nuclear physics principles like the liquid-drop model of the atomic nucleus. The specific combinations of its 61 protons with any number of neutrons fail to create a binding energy configuration that is stable against radioactive decay, making it unique among the lanthanides.
8. Why do Promethium salts appear coloured and also emit a glow?
These are two separate phenomena. The pink or red colour of its salts is caused by f-f electronic transitions within the Promethium ions, a trait common to many lanthanides. The pale blue-green glow, however, is due to radioluminescence. The high-energy beta particles emitted by the radioactive Promethium strike and excite surrounding atoms, which then release that energy as visible light, causing the material to glow.
9. How does Promethium's stable +3 oxidation state compare with other lanthanides?
Promethium's stable +3 oxidation state is highly typical for the lanthanide series. Most lanthanides favour this state because it involves losing the two outer 6s electrons and one 5d or 4f electron, leading to a stable configuration. Unlike some other lanthanides (like Europium or Cerium) that can exhibit +2 or +4 states to achieve a half-filled or empty f-orbital, Promethium's 4f⁵ configuration offers no such special stability, making the +3 state the most energetically favourable and dominant one.
10. What makes Promethium-147 ideal for use in atomic batteries for space probes?
Promethium-147 is exceptionally suited for long-duration power sources in space for several reasons:
- Pure Beta Emitter: It primarily releases beta particles, which are easily shielded, minimising harmful penetrating gamma radiation.
- Optimal Half-Life: Its half-life of 2.62 years is long enough to provide power for multi-year missions but short enough to ensure a high power density.
- Reliability: As a radioisotope power source, it generates a consistent electrical current from radioactive decay without needing sunlight or having moving parts, making it highly reliable for deep space applications.
