chemical element
A chemical element is a chemical substance whose atoms all have the same number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8: each oxygen atom has 8 protons in its ...
; it has
symbol
A symbol is a mark, Sign (semiotics), sign, or word that indicates, signifies, or is understood as representing an idea, physical object, object, or wikt:relationship, relationship. Symbols allow people to go beyond what is known or seen by cr ...
Rh and
atomic number
The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (''n''p) or the number of pro ...
45. It is a very rare, silvery-white, hard,
corrosion-resistant
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion enginee ...
transition metal
In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. The lanthanide and actinid ...
. It is a
noble metal
A noble metal is ordinarily regarded as a metallic chemical element, element that is generally resistant to corrosion and is usually found in nature in its native element, raw form. Gold, platinum, and the other platinum group metals (ruthenium ...
and a member of the
platinum group
The platinum-group metals (PGMs) are six noble, precious metallic elements clustered together in the periodic table. These elements are all transition metals in the d-block (groups 8, 9, and 10, periods 5 and 6).
The six platinum-group ...
. It has only one naturally occurring
isotope
Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...
, which is 103Rh. Naturally occurring rhodium is usually found as a free metal or as an alloy with similar metals and rarely as a chemical compound in minerals such as bowieite and
rhodplumsite
Rhodplumsite is a rare rhodium-lead sulfide mineral, chemical formula Rh3Pb2S2. It was originally discovered within a platinum nugget, in grains up to 40 μm in size. Its name originates from its composition; rhodium and lead (plumbum in Latin
...
. It is one of the rarest and most valuable
precious metal
Precious metals are rare, naturally occurring metallic chemical elements of high Value (economics), economic value. Precious metals, particularly the noble metals, are more corrosion resistant and less reactivity (chemistry), chemically reac ...
s. Rhodium is a
group 9 Group 9 may refer to:
* Group 9 element
* Group 9 Rugby League
*"Group 9", Australian arts collective, whose members included John Dowie
{{disambig
* Rhodium neutron detectors are used in nuclear reactors to measure neutron flux levels—this method requires a digital filter to determine the current neutron flux level, generating three separate signals: immediate, a few seconds delay, and a minute delay, each with its own signal level; all three are combined in the rhodium detector signal. The three Palo Verde nuclear reactors each have 305 rhodium neutron detectors, 61 detectors on each of five vertical levels, providing an accurate 3D "picture" of reactivity and allowing fine tuning to consume the nuclear fuel most economically.
In automobile manufacturing, rhodium is also used in the construction of headlight reflectors.Stwertka, Albert. ''A Guide to the Elements'', Oxford University Press, 1996, p. 125.
File:Rhodium 78g sample.jpg, A 78 g sample of rhodium
Image:Aufgeschnittener Metall Katalysator für ein Auto.jpg, Cut-away of a metal-core catalytic converter
Image:White-gold--rhodium-plated.jpg, Rhodium-plated white gold wedding ring
Image:Rhodium foil and wire.jpg, Rhodium foil and wire
Precautions
Being a
noble metal
A noble metal is ordinarily regarded as a metallic chemical element, element that is generally resistant to corrosion and is usually found in nature in its native element, raw form. Gold, platinum, and the other platinum group metals (ruthenium ...
, pure rhodium is inert and harmless in elemental form. However, chemical complexes of rhodium can be reactive. For rhodium chloride, the
median lethal dose
In toxicology, the median lethal dose, LD50 (abbreviation for " lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a given substance. The value of LD50 for a substance is the dose re ...
(LD50) for rats is 198 mg () per kilogram of body weight. Like the other noble metals, rhodium has not been found to serve any biological function.
People can be exposed to rhodium in the workplace by inhalation. The
Occupational Safety and Health Administration
The Occupational Safety and Health Administration (OSHA; ) is a regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. The United States Congress established ...
(OSHA) has specified the legal limit (
Permissible exposure limit
The permissible exposure limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a chemical substance or physical agents such as high level noise. Permissible exposure limits were established by the Occupational ...
) for rhodium exposure in the workplace at 0.1 mg/m3 over an 8-hour workday, and the
National Institute for Occupational Safety and Health
The National Institute for Occupational Safety and Health (NIOSH, ) is the List of United States federal agencies, United States federal agency responsible for conducting research and making recommendations for the prevention of work-related occ ...
(NIOSH) has set the
recommended exposure limit
A recommended exposure limit (REL) is an occupational exposure limit that has been recommended by the United States National Institute for Occupational Safety and Health. The REL is a level that NIOSH believes would be protective of worker safety ...
(REL), at the same level. At levels of 100 mg/m3, rhodium is
immediately dangerous to life or health
The term immediately dangerous to life or health (IDLH) is defined by the US National Institute for Occupational Safety and Health (NIOSH) as exposure to airborne contaminants that is "likely to cause death or immediate or delayed permanent adver ...
. For soluble compounds, the PEL and REL are both 0.001 mg/m3.
See also
*
2000s commodities boom
The 2000s commodities boom, commodities super cycle or China boom was the rise of many physical commodity prices (such as those of food, oil, metals, chemicals and fuels) during the early 21st century (2000–2014), following the Great Commoditie ...
*
2020s commodities boom
The 2020s commodities boom refers to the rise of many commodity prices in the early 2020s following the COVID-19 pandemic. The COVID-19 recession initially made commodity prices drop, but lockdowns, supply chain bottlenecks, and dovish monetary ...
*
Bullion
Bullion is non-ferrous metal that has been refined to a high standard of elemental purity. The term is ordinarily applied to bulk metal used in the production of coins and especially to precious metals such as gold and silver. It comes from ...
*
Bullion coin
A bullion coin (also known as a specie) is a coin struck from highly refined precious metal (bullion) and kept as a store of value or an investment rather than used in day-to-day commerce, or collectable, with numismatic value beyond that of its ...
*
Rhodium compounds
Rhodium is a chemical element; it has symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isoto ...
The Periodic Table of Videos
''Periodic Videos'' (also known as ''The Periodic Table of Videos'') is a video project and YouTube channel on chemistry. It consists of a series of videos about chemical elements and the periodic table, with additional videos on other topics i ...