Rhodium is a actinic aspect that is a rare, silvery-white, hard, and chemically apathetic alteration metal and a affiliate of the platinum group. It has the actinic attribute Rh and diminutive amount 45. It is composed of alone one isotope, 103Rh. Naturally occurring rhodium is begin as the chargeless metal, adulterated with agnate metals, and never as a actinic compound. It is one of the rarest adored metals and one of the a lot of cher (gold has back taken over the top atom of amount per ounce).
Rhodium is a alleged blue-blooded metal, advancing to corrosion, begin in platinum- or nickel ores calm with the added associates of the platinum accumulation metals. It was apparent in 1803 by William Hyde Wollaston in one such ore, and called for the rose blush of one of its chlorine compounds, produced afterwards it reacted with the able acerbic admixture aqua regia.
The element's above use (about 81% of apple rhodium production) is as one of the catalysts in the three-way catalytic converters of automobiles. Because rhodium metal is apathetic adjoin bane and a lot of advancing chemicals, and because of its rarity, rhodium is usually adulterated with platinum or aegis and activated in high-temperature and corrosion-resistive coatings. White gold is generally argent with a attenuate rhodium band to advance its optical consequence while admirable argent is generally rhodium argent for befoul resistance.
Rhodium detectors are acclimated in nuclear reactors to admeasurement the neutron alteration level.
Characteristics
Rhodium is a hard, silvery, durable metal that has a high reflectance. Rhodium metal does not normally form an oxide, even when heated. Oxygen is absorbed from the atmosphere only at the melting point of rhodium, but is released on solidification. Rhodium has both a higher melting point and lower density than platinum. It is not attacked by most acids: it is completely insoluble in nitric acid and dissolves slightly in aqua regia.
Rhodium belongs to group 9 of the periodic table but has an atypical configuration in its outermost electron shells compared to the rest of the members. This can also be observed in the neighborhood of niobium (41), ruthenium (44), and palladium (46).
Naturally occurring rhodium is composed of only one isotope, 103Rh. The most stable radioisotopes are 101Rh with a half-life of 3.3 years, 102Rh with a half-life of 207 days, 102mRh with a half-life of 2.9 years, and 99Rh with a half-life of 16.1 days. Twenty other radioisotopes have been characterized with atomic weights ranging from 92.926 u (93Rh) to 116.925 u (117Rh). Most of these have half-lives shorter than an hour, except 100Rh (half-life: 20.8 hours) and 105Rh (half-life: 35.36 hours). There are also numerous meta states, the most stable being 102mRh (0.141 MeV) with a half-life of about 2.9 years and 101mRh (0.157 MeV) with a half-life of 4.34 days. (See isotopes of rhodium).
The primary decay mode before the only stable isotope, 103Rh, is electron capture and the primary mode after is beta emission. The primary decay product before 103Rh is ruthenium and the primary product after is palladium.
Applications
The primary use of this element is in automobiles as a catalytic converter, which changes harmful emissions from the engine into less polluting gases.
Rhodium is used as an alloying agent for hardening and improving the corrosion resistance of platinum and palladium. These alloys are used in furnace windings, bushings for glass fiber production, thermocouple elements, electrodes for aircraft spark plugs, and laboratory crucibles.
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