Dictionary of Meaning
<<Back
Please select a letter:
A |
B |
C |
D |
E |
F |
G |
H |
I |
J |
K |
L |
M |
N |
O |
P |
Q |
R |
S |
T |
U |
V |
W |
X |
Y |
Z |
0-9
Click here for Shopping
Iridium
*** Shopping-Tip: Iridium
{{Otheruses4|the chemical element|the communications satellite|Iridium (satellite)}}
{{Elementbox_header | number=77 | symbol=Ir | name=iridium | left=
osmium .html">platinum
_above=rhodium|Rh | below=
meitnerium Mt | color1=#ffc0c0 | color2=black }}
{{Elementbox_series |
transition metals }}
{{Elementbox_groupperiodblock | group=9 | period=6 | block=d }}
{{Elementbox_appearance_img | Ir,77| silvery white }}
{{Elementbox_atomicmass_gpm |
1 E-25 kg 192.217List of elements by atomic mass (3) }}
{{Elementbox_econfig | [
xenon Xe] 4f
14 5d
7 6s
2 }}
{{Elementbox_epershell | 2, 8, 18, 32, 15, 2 }}
{{Elementbox_section_physicalprop | color1=#ffc0c0 | color2=black }}
{{Elementbox_phase |
solid }}
{{Elementbox_density_gpcm3nrt | 22.65 }}
{{Elementbox_densityliq_gpcm3mp | 19 }}
{{Elementbox_meltingpoint | k=2719 | c=2446 | f=4435 }}
{{Elementbox_boilingpoint | k=4701 | c=4428 | f=8002 }}
{{Elementbox_heatfusion_kjpmol | 41.12 }}
{{Elementbox_heatvaporiz_kjpmol | 231.8 }}
{{Elementbox_heatcapacity_jpmolkat25 | 25.10 }}
{{Elementbox_vaporpressure_katpa | 2713 | 2957 | 3252 | 3614 | 4069 | 4659 | comment= }}
{{Elementbox_section_atomicprop | color1=#ffc0c0 | color2=black }}
{{Elementbox_crystalstruct | cubic face centered }}
{{Elementbox_oxistates | 2, 3, '''4''', 6
(mildly
base (chemistry) basic oxide) }}
{{Elementbox_electroneg_pauling | 2.20 }}
{{Elementbox_ionizationenergies2 | 880 | 1600 }}
{{Elementbox_atomicradius_pm |
1 E-10 m 135 }}
{{Elementbox_atomicradiuscalc_pm |
1 E-10 m 180 }}
{{Elementbox_covalentradius_pm |
1 E-10 m 137 }}
{{Elementbox_section_miscellaneous | color1=#ffc0c0 | color2=black }}
{{Elementbox_magnetic | no data }}
{{Elementbox_eresist_ohmmat20 | 47.1 n}}
{{Elementbox_thermalcond_wpmkat300k | 147 }}
{{Elementbox_thermalexpansion_umpmkat25 | 6.4 }}
{{Elementbox_speedofsound_rodmpsat20 | 4825 }}
{{Elementbox_youngsmodulus_gpa | 528 }}
{{Elementbox_shearmodulus_gpa | 210 }}
{{Elementbox_bulkmodulus_gpa | 320 }}
{{Elementbox_poissonratio | 0.26 }}
{{Elementbox_mohshardness | 6.5 }}
{{Elementbox_vickershardness_mpa | 1760 }}
{{Elementbox_brinellhardness_mpa | 1670 }}
{{Elementbox_cas_number | 7439-88-5 }}
{{Elementbox_isotopes_begin | isotopesof=iridium | color1=#ffc0c0 | color2=black }}
{{Elementbox_isotopes_decay | mn=189 | sym=Ir
| na=
synthetic radioisotope syn | hl=13.2 d
| dm=
electron capture ε | de=0.532 | pn=189 | ps=
osmium Os }}
{{Elementbox_isotopes_decay | mn=190 | sym=Ir
| na=
synthetic radioisotope syn | hl=11.8 d
| dm=
electron capture ε | de=2.000 | pn=190 | ps=
osmium Os }}
{{Elementbox_isotopes_stable | mn=191 | sym=Ir | na=37.3% | n=114 }}
{{Elementbox_isotopes_decay2 | mn=192 | sym=Ir
| na=
synthetic radioisotope syn | hl=73.83 d
| dm1=
beta emission β | de1=1.460 | pn1=192 | ps1=
platinum Pt
| dm2=
electron capture ε | de2=1.046 | pn2=192 | ps2=
osmium Os }}
{{Elementbox_isotopes_decay | mn=192
Nuclear isomer m | sym=Ir
| na=
synthetic radioisotope syn | hl=241
year y
| dm=
isomeric transition IT | de=0.155 | pn=192 | ps=Ir }}
{{Elementbox_isotopes_stable | mn=193 | sym=Ir | na=62.7% | n=116 }}
{{Elementbox_isotopes_decay | mn=194 | sym=Ir
| na=
synthetic radioisotope syn | hl=19.3 h
| dm=
beta emission β< | de=2.247 | pn=194 | ps=
platinum Pt }}
{{Elementbox_isotopes_decay | mn=195 | sym=Ir
| na=
synthetic radioisotope syn | hl=2.5 h
| dm=
beta emission β< | de=1.120 | pn=195 | ps=
platinum Pt }}
{{Elementbox_isotopes_end}}
{{Elementbox_footer | color1=#ffc0c0 | color2=black }}
'''Iridium''' is a
chemical element in the
periodic table that has the symbol '''Ir''' and
atomic number 77. A dense, very hard, brittle, silvery-white
transition metal of the
platinum group platinum family, iridium is used in high strength
alloys that can withstand high temperatures and occurs in natural alloys with
platinum or
osmium. Iridium is notable for being the most corrosion resistant element known and for its association with the
Cretaceous-Tertiary extinction event#Impact_event_and_iridium demise of the
dinosaurs. It is used in high temperature apparatus, electrical contacts, and as a hardening agent for platinum.
Notable characteristics
A
platinum group platinum family metal, iridium is white, resembling
platinum, but with a slight yellowish cast. Due to its extreme hardness and brittle properties, iridium is difficult to machine, form, or work. Iridium is the most
corrosion-resistant metal known. Iridium cannot be attacked by any
acids or by
aqua regia, but it can be attacked by molten
salts, such as
sodium chloride NaCl and
sodium cyanide NaCN.
The measured
density of this element is only slightly lower than that of
osmium, which is often listed as the heaviest element known. However, calculations of density from the
space lattice may produce more reliable data for these elements than actual measurements and give a density of 22650
kilogram per cubic metre kg/m³ for iridium versus 22610 kg/m³ for osmium. Definitive selection between the two is therefore not possible at this time.
Applications
The principal use of iridium is as a hardening agent in platinum alloys. Other uses:
*For making
crucibles and devices that require high temperatures.
*Electrical contacts (notable example: Pt/Ir
sparkplugs).
*Osmium/iridium alloys are used for tipping
fountain pen nibs and for
compass bearings.
*Iridium is commonly used in complexes like
and other complexes in
PLED polymer LED technology to increase the efficiency from 25% to almost 100% due to triplet harvesting.
*Iridium is used as a
catalyst for carbonylation of methanol to produce
acetic acid
At one time iridium, as an alloy with platinum, was used in bushing the vents of heavy
ordnance and, in a finely powdered condition (iridium black), for painting
porcelain black.
History
Iridium was discovered in
1803 by
Smithson Tennant in London, England along with
osmium in the dark-colored residue of dissolving crude
platinum in
aqua regia (a mixture of
hydrochloric acid hydrochloric and
nitric acid). The element was named after the Latin word for
rainbow (''iris''; ''iridium'' means "of rainbows") because many of its salts are strongly colored.
An alloy of 90% platinum and 10% iridium was used in
1889 to construct the standard
metre bar and
kilogram mass, kept by the
Bureau International des Poids et Mesures International Bureau of Weights and Measures near
Paris. The metre bar was replaced as the definition of the fundamental unit of length in
1960 (see
krypton), but the kilogram prototype is still the international standard of mass.
The
Cretaceous-Tertiary extinction event KT event of 65 million years ago, marking the temporal border between the
Cretaceous and
Tertiary eras of
Geologic Timescale geological time, was identified by a thin
stratum of iridium-rich clay. A team led by
Luis Alvarez (
1980) proposed an extraterrestrial origin for this iridium, attributing it to an
asteroid or
comet impact near what is now
Yucatan Peninsula. Their theory is widely accepted to explain the demise of the
dinosaurs. Dewey M. McLean and others argue that the iridium may have been of
volcano volcanic origin instead. The
Earth's core is rich in iridium, and Piton de la Fournaise on
Réunion, for example, is still releasing iridium today.
Occurrence
Iridium is found uncombined in nature with platinum and other platinum group metals in
alluvium alluvial deposits. Naturally occurring iridium alloys include
osmiridium and
iridiosmium, both of which are mixtures of iridium and osmium. It is recovered commercially as a by-product from
nickel mining and processing.
Iridium is rare on
Earth, but relatively common in
meteorites.
Isotopes
There are two natural
isotopes of iridium, and many
radioisotopes, the most stable radioisotope being Ir-192 with a
half-life of 73.83 days. Ir-192
beta decays into platinum-192, while most of the other radioisotopes decay into osmium.
Precautions
Image:Iridium_foil.jpg thumb|Iridium foil
Iridium metal is mostly non-toxic due to its relative unreactivity, but iridium compounds should be considered highly toxic.
References
-
Los Alamos National Laboratory - Iridium
External links
{{Commons|Iridium}}
{{wiktionary|iridium}}
-
WebElements.com - Iridium
-
Picture in the element collection from Pniok.de
Category:Chemical elements
Category:Transition metals
Category:Precious metals
ca:Iridi
cs:Iridium
de:Iridium
et:Iriidium
el:ΙÏ?ίδιο
es:Iridio
eo:Iridio
fr:Iridium
ko:�리�
io:Iridio
ia:Iridium
is:IridÃn
it:Iridio
he:×?ירידיו×?
ku:Îrîdyûm
lv:Irīdijs
lt:Iridis
hu:IrÃdium
nl:Iridium (element)
ja:イリジウãƒ
no:Iridium
nn:Iridium
oc:Iridi
pl:Iryd
pt:IrÃdio
ru:Иридий
simple:Iridium
sl:Iridij
sr:Иридијум
fi:Iridium
sv:Iridium
th:à¸à¸´à¸£à¸´à¹€à¸”ียม
uk:Іридій
zh:铱
Iridium Ir
----
This template should be :Template substitution substituted.
Category:Chemical element symbol templates {{PAGENAME}}
*** Shopping-Tip: Iridium
