Rhodium

Definition: Rhodium

Rhodium

Noun

1. A white hard metallic element that is one of the platinum group and is found in platinum ores; used in alloys with platinum.

Etymology: Rhodium \Rho"di*um\, noun. [New Latin expression, from the Greek expression "ro`don the rose. So called from the rose-red color of certain of its solutions. See Rhododendron.]. (Websters 1913)

Specialty Definitions: Rhodium

Domain	Definitions
Chemistry	A silvery-white, hard but ductile metal. Source: European Union. (references)
Chemistry	Chemical element:atomic number 45. Source: European Union. (references)
Mining	A. An element of the platinum group, Symbol: Rh.b. An isometric mineral, RhPt . (references)
Source: compiled by the editor from various references; see credits.

Top

Specialty Definition: Rhodium

(From Wikipedia, the free Encyclopedia)

General

Name, Symbol, Number

Rhodium, Rh, 45

Chemical series

Transition metals

Group, Period, Block

9, 5 , d

Density, Hardness

12450 kg/m³, 6

Appearance

Silvery white metallic

Atomic Properties

Atomic weight

102.90550 amu

Atomic radius (calc.)

135 (173) pm

Covalent radius

135 pm

van der Waals radius

no data

Electron configuration

[Kr]4d4d⁸ 5s¹

e^- 's per energy level

2, 8, 18, 16, 1

Oxidation states (Oxide)

2, 3, 4 (amphoteric)

Crystal structure

Face centered cubic

Physical Properties

State of matter

Solid (__)

Melting point

2237 K (3567 °F)

Boiling point

3968 K (6683 °F)

Molar volume

8.28 ×1010^-3 m³/mol

Heat of vaporization

493 kJ/mol

Heat of fusion

21.5 kJ/mol

Vapor pressure

0.633 Pa at 2239 K

Speed of sound

4700 m/s at 293.15 K

Miscellaneous

Electronegativity

2.28 (Pauling scale)

Specific heat capacity

0.242 J/(kg*K)

Electrical conductivity

21.1 10⁶/m ohm

Thermal conductivity

150 W/(m*K)

1^st ionization potential

719.7 kJ/mol

2^nd ionization potential

1740 kJ/mol

3^rd ionization potential

2997 kJ/mol

Most Stable Isotopes

iso	NA	half-life	DM	DE MeV	DP
¹⁰¹Rh	{syn.}	3.3 y	&epsilon	0.542	¹⁰¹Ru
¹⁰²Rhm	{syn.}	~2.9 y	ε IT	2.464 0.141	¹⁰²Ru
¹⁰³Rh	100%	Rh is stable with 58 neutrons

SI units & STP are used except where noted.

Rhodium is a chemical element in the periodic table that has the symbol Rh and atomic number 45. A rare silvery-white hard transition metal, rhodium is a member of the platinum group, is found in platinum ores and is used in alloys with platinum and as a catalyst.

Notable Characteristics

Rhodium is a hard silvery white and durable metal that has a high reflectance. It changes in air to the resquioxide while slowly cooling from a red hot state but at higher temperatures converts back to the metal. Rhodium has both a higher melting point and lower density than platinum. It is not attacked by acids and only dissolves in aqua regia.

Applications

The primary use of this element is as an alloying agent for hardening 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. Other uses;

It is used as an electrical contact material due to its low electrical resistance, low and stable contact resistance, and its high corrosion resistance.
Plated rhodium, made by electroplating or evaporation, is extremely hard and is used for optical instruments.
This metal finds use in jewelry and for decorations.
It is also a highly useful catalyst in a number of industrial processes (notably it is used in the catalytic system of automobile catalytic converters).

History

Rhodium (Greek rhodon meaning "rose") was discovered in 1803 by William Hyde Wollaston soon after his discovery of palladium. Wollaston made this discovery in England using crude platinum ore that he presumably obtained from South America.

His procedure involved dissolving the ore in aqua regia, neutralizing the acid with sodium hydroxide (NaOH). He then precipitated the platinum metal by adding ammonium chloride, NHH₄Cl, as ammonium chloroplatinate. The element palladium was removed as palladium cyanide after treating the solution with mercuric cyanide. The material that remained was a red substance with rhodium chloride salts and rhodium metal was isolated via reduction with hydrogen gas.

Occurrence

The industrial extraction of rhodium is complex as the metal occurs in ores mixed with other metals such as palladium, silver, platinum, and gold. It is found in platinum ores and obtained free as a white inert metal which it is very difficult to fuse. Principal sources of this element are located in river sands of the Ural Mountains, in North and South America and also in the copper-nickel sulfide mining area of the Sudbury, Ontario region. Although the quantity at Sudbury is very small, the large amount of nickel ore processed makes rhodium recovery cost effective. However, the annual world production of this element is only 7 or 8 tons and there are very few rhodium minerals.

Isotopes

Naturally occurring rhodium is composed of only one isotope (Rh-103). The most stable radioisotopes are Rh-101 with a half-life of 3.3 years, Rh-102 with a half-life of 207 days, and Rh-99 with a half-life of 16.1 days. Twenty other radioisotopes have been characterized with atomic weights ranging from 92.926 amu (Rh-93) to 116.925 amu (Rh-117). Most of these have half-lifes that are less than an hour except Rh-100 (half-life: 20.8 hours) and Rh-105 (half-life: 35.36 hours). There are also numerous meta states with the most stable being Rhm-102 (0.141 MeV) with a half-life of about 2.9 years and Rhm-101 (0.157 MeV) with a half-life of 4.34 days.

The primary decay mode before the only stable isotope, Rh-103, is electron capture and the primary mode after is beta emission. The primary decay product before Rh-103 is ruthenium and the primary product after is palladium.

Precautions

Compounds that contain rhodium are not encountered by most people often and should be considered to by highly toxic and carcinogenic. Rhodium compounds can stain human skin very strongly. This element plays no biological role in humans.

External Links

Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Rhodium."

Top

Synonym: Rhodium

Synonym: atomic number 45 (n). (additional references)

Top

Crosswords: Rhodium

English words defined with "rhodium": Lignum rhodium ♦ Noble metals ♦ Platinum metals ♦ Rhodammonium, Rhodic ♦ William Hyde Wollaston, Wollaston. (references)

Specialty definitions using "rhodium": alloy 11 ♦ platinum 13% rhodium, platinum 30% rhodium ♦ rhodium gold ♦ thermoelectric metals. (references)

Top

Commercial Usage: Rhodium

Domain	Title
Books	Index verborum in Apollonium Rhodium (reference) Rhodium Catalyzed Hydroformylation (reference) Rhodium complex catalyzed reactions : kinetic and mechanistic studies (reference) (more book examples)
Source: compiled by the editor from various references; see credits.

Top

Usage Frequency: Rhodium

"Rhodium" is generally used as a noun (singular) -- approximately 100.00% of the time. "Rhodium" is used about 24 times out of a sample of 100 million words spoken or written in English. Its rank is based on over 700,000 words used in the English language. Some parts-of-speech are not covered due to the samples used by the British National Corpus. (note: percents less than one-hundredth of one percent have been omitted)

Parts of Speech	Percent	Usage per 100 Million Words	Rank in English
Noun (singular)	100%	24	71,196

Source: compiled by the editor from several corpora; see credits.

Top

Expressions: Rhodium

Expressions using "rhodium": Lignum rhodium ♦ platinum 13% rhodium ♦ platinum 30% rhodium. Additional references.
Source: compiled by the editor from various references; see credits.

Top

Frequency of Internet Keywords: Rhodium

The following statistics estimate the number of searches per day across the major English-language search engines as identified by various trade publications. Hyperlinks lead to commercial use of the expression at Amazon.com.

Expression	Frequency per Day
rhodium	203
rhodium plating	202
rhodium jewelry	9
chemistry rhodium	7
rhodium oil	5
rhodium price	4
rhodium ring	4
finish rhodium	3
palladium rhodium trading	3
black rhodium	3
rhodium tiara	2
archive rhodium	2
rhodium plating jewelry	2
hive rhodium	2
plated rhodium	2
chain rhodium	2
jewelry plated rhodium	2
drug rhodium	2
Source: compiled by the editor from various references; see credits.

Top

Modern Translations: Rhodium

Language		Translations for "rhodium"; alternative meanings/domain in parentheses.
Afrikaan		rodium. (various references)

Albanian		rodium. (various references)

Bulgarian		родий. (various references)

Chinese		銠 , 铑. (various references)

Danish		rhodium. (various references)

Dutch		rodium. (various references)

Esperanto		rodio. (various references)

French		rhodium. (various references)

German		Rhodium. (various references)

Greek		ρόδιο. (various references)

Hungarian		ródium. (various references)

Italian		rodio. (various references)

Japanese Kanji		ロシア文字 (lock, locker, locker room, lock-file, Lockheed, locking, lockout, logic, logic analyzer, logic programming, logical, logistics, loss, loss leader, loss of time, lost, lost ball, Lost Generation, lost time, Rochester, rock, rock fiber, rock music, rock 'n' roll, rock wool, rock-climbing, rocking, rocking chair, rockoon, rose, Rosetta Stone, rosette, Rossignol, roster, Russian character). (various references)

Japanese Katakana		ロジウム . (various references)

Pig Latin		odiumrhay

Portuguese		ródio. (various references)

Russian		родий. (various references)

Serbo-Croatian		rodijum. (various references)

Spanish		rodio. (various references)

Swedish		rodium. (various references)

Thai		ธาตุโรเดียม (สัญลักษณ์แทนคือ Rh). (various references)

Turkish		rodyum. (various references)

Ukranian		родій, трояндове дерево. (various references)
Source: compiled by the editor from various translation references.

Top

Derivations & Misspellings: Rhodium

Derivations
	Words beginning with "rhodium": rhodiums. (additional references)
Misspellings
	"Rhodium" is suggested in spellcheckers for the following: Erodium, khudian, Rhidian, rhigian, rhodians, rhodie, rhodies, Rhodnius. (additional references)
Source: compiled by the editor, based on several corpora (additional references).

Top

Rhyming with "Rhodium"

# of Phoneme Matches	Pronunciation	Word(s) rhyming with "rhodium" (pronounced rō"dēum)
5	-ō" d ē u m	Plasmodium, podium, sodium.
4	-d ē u m	compendium, idiom, indium, iridium, medium, myocardium, nephridium, palladium, presidium, radium, stadium, tedium, vanadium.
3	-ē u m	alluvium, ammonium, aquarium, atrium, auditorium, axiom, bacterium, barium, beryllium, cadmium, calcium, cesium, chromium, colloquium, condominium, consortium, crematorium, delirium, deuterium, disequilibrium, emporium, equilibrium, europium, fermium, gallium, geranium, gonium, gymnasium, hafnium, harmonium, helium, Herbarium, holmium, honorarium, lawrencium, linoleum, lithium, magnesium, millennium, minium, moratorium, neptunium, niobium, nobelium, opium, opprobrium, osmium, pandemonium, paramecium, petroleum, planetarium, plutonium, polonium, potassium, premium, promethium, protium, psyllium, requiem, selenium, strontium, superpremium, symposium, tellurium, thallium, thorium, titanium, tritium, uranium, yttrium, zirconium.
Source: compiled by the editor (additional references); see credits.

Top

Anagrams: Rhodium

Scrabble® Enable2K-Verified Anagrams
	Direct Anagrams: humidor.
	Words within the letters "d-h-i-m-o-r-u"
	-2 letters: duomi, houri, humid, humor, mohur, murid, odium.
	-3 letters: dorm, doum, dour, drum, duro, hour, modi.
	-4 letters: dim, dom, dor, duh, dui, duo, hid, him, hod, hum, mho, mid, mir, mod, mor, mud, ohm, oud, our, rho, rid, rim, rod, rom, rum, udo, urd.
	-5 letters: do, hi, hm, ho, id, mi, mo, mu, od, oh.
	Words containing the letters "d-h-i-m-o-r-u"
	+1 letter: humidors, rhodiums.
	+2 letters: hydronium.
	+3 letters: dimorphous, hydroniums, rheumatoid.
	+4 letters: rhomboideus, thermoduric.
	+5 letters: malnourished, radiothorium.
Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro.