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iridium    音标拼音: [ɪr'ɪdiəm]
n. 铱

铱

iridium
n 1: a heavy brittle metallic element of the platinum group;
used in alloys; occurs in natural alloys with platinum or
osmium [synonym: {iridium}, {Ir}, {atomic number 77}]

iridium \i*rid"i*um\ ([-i]*r[i^]d"[i^]*[u^]m), n. [NL., fr. L.
iris, iridis, the rainbow. So called from the iridescence of
some of its solutions. See {Iris}.] (Chem.)
A rare metallic element of atomic number 77, of the same
group as platinum, which it much resembles, being
silver-white and indifferent to most corrosive agents, but
harder, more brittle, and with a higher melting temperature
(2410[deg] C, versus platinum 1772[deg] C). With the
exception of osmium, it is the heaviest substance known, its
specific gravity being 22.4. Symbol Ir. Atomic weight 192.22.
[1913 Webster PJC]

Note: Iridium usually occurs as a native alloy with osmium
(iridosmine or osmiridium), which may occur alone or
with platinum. Iridium, as an alloy with platinum, is
used in bushing the vents of heavy ordnance. It is also
used for the points of gold pens, and in a finely
powdered condition (iridium black), for painting
porcelain black.
[1913 Webster]

iridium
Symbol: Ir
Atomic number: 77
Atomic weight: 192.217
Very hard and brittle, silvery metallic transition element. It has a
yellowish cast to it. Salts of iridium are highly colored. It is the
most corrosion resistant metal known, not attacked by any acid, but is
attacked by molten salts. There are two natural isotopes of iridium, and
4 radioisotopes, the most stable being Ir-192 with a half-life of 73.83
days. Ir-192 decays into {platinum}, while the other radioisotopes decay
into {osmium}. Iridium is used in high temperature apparatus, electrical
contacts, and as a hardening agent for platinum. Discovered in 1803 by
Smithson Tennant in England. The name comes from the Greek word iris,
which
means rainbow. Iridium metal is generally non-toxic due to its relative
unreactivity, but iridium compounds should be considered highly toxic.


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  • Iridium - Wikipedia
    Iridium is a chemical element; it has the symbol Ir and atomic number 77 This very hard, brittle, silvery-white transition metal of the platinum group is considered the second-densest naturally occurring metal (after osmium), with a density of 22 56 g cm 3 (0 815 lb cu in) as defined by experimental X-ray crystallography [a] 191 Ir and 193 Ir are the only two naturally occurring isotopes of
  • The Only Truly Global Network | Iridium Satellite Communications
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  • Iridium | Definition, Properties, Uses | Britannica
    Iridium, chemical element, one of the platinum metals of Groups 8–10 (VIIIb), Periods 5 and 6, of the periodic table It is very dense and rare and is used in platinum alloys A precious, silver-white metal, iridium is hard and brittle, but it becomes ductile and can be worked at a white heat
  • Iridium - Element information, properties and uses | Periodic Table
    Iridium is the most corrosion-resistant material known It is used in special alloys and forms an alloy with osmium, which is used for pen tips and compass bearings It was used in making the standard metre bar, which is an alloy of 90% platinum and 10% iridium It is also used for the contacts in spark plugs because of its high melting point and low reactivity
  • Iridium Facts - Ir or Atomic Number 77 - Science Notes and Projects
    Get iridium facts Discover the properties, uses, sources, and biological effects of the element with symbol Ir and atomic number 77
  • What Is Iridium And Is It More Expensive Than Gold? - IFLScience
    What is iridium? Iridium is a chemical element that has the atomic number 77 and is classed as a transition metal Iridium is solid at room temperature
  • Iridium Element Facts - chemicool. com
    Iridium was used in making the international standard kilogram, which is an alloy of 90% platinum and 10% iridium Radioactive isotopes of iridium are used in radiation therapy for the treatment of cancer
  • Iridium | Ir (Element) - PubChem
    Chemical element, Iridium, information from authoritative sources Look up properties, history, uses, and more
  • Iridium: What it Is, Applications, Example - Investopedia
    Iridium is a rare and expensive corrosion-resistant metal Discover why iridium is used in the manufacture of aircraft, spark plugs, and tech devices
  • Element: Iridium — Periodic table
    Iridium is a chemical element; it has symbol Ir and atomic number 77 This very hard, brittle, silvery-white transition metal of the platinum group, is considered the second-densest naturally occurring metal (after osmium) with a density of 22 56 g cm3 (0 815 lb cu in) as defined by experimental X-ray crystallography 191Ir and 193Ir are the only two naturally occurring isotopes of iridium





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