Iridium

Tecken	Ir
Atomnummer	77
Grupp	9 (Koboltgruppen)
Period	6
Block	d
Ämnesklass	Övergångsmetall

Utseende	Silvery white
Färg	Silver

Antal protoner	77 p+
Antal neutroner	115 n0
Antal elektroner	77 e-

Från Wikipedia, den fria encyklopedinIridium är en vit metall med något gulaktig ton i platinafamiljen. Till platinametallerna hör även platina, osmium, palladium, rutenium och rodium. Iridium upptäcktes av engelsmannen Smithson Tennant i resterna efter att råmaterial av platina hade upplösts av kungsvatten. Namnet kommer av latinets iris, ”regnbåge”, vilket syftar på iridiums salter som har starka färger. Iridium upptäcktes 1803, av den brittiske kemisten Smithson Tennant. Det var också han som namngav det nyupptäckta elementet.

Fas vid STP	Fast
Densitet	22.56 g/cm3
Relativ atommassa	192.217 u

Smältpunkt	2719 K 2445.85 °C 4434.53 °F
Kokpunkt	4403 K 4129.85 °C 7465.73 °F
Ångbildningsvärme	563.58 kJ/mol

Elektronegativitet (Paulingskalan)	2.2
Elektronaffinitet	150.94 kJ/mol
Oxidationstal	−3, −1, 0, +1, +2, +3, +4, +5, +6, +7, +8, +9 ()
Jonisationspotential	880 kJ/mol 1600 kJ/mol

Elektronkonfiguration Kortfattad konfiguration	[Xe] 4f14 5d7 6s2
Elektronkonfiguration Full konfiguration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d7 6s2
Elektronkonfigurationsdiagram	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d7 6s2
Elektroner per skal	2, 8, 18, 32, 15, 2
Outer shell electrons	2
Valence electrons (incl. d)	9
Valency-elektroner	2,3,4
Bohrs atommodell	Figur: Skaldiagram över Iridium (Ir) atom.
Orbitaldiagram 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 6s

Upptäckt och första isolation

Smithson Tennant (1803)

Upptäckten av iridium Chemists who studied platinum dissolved it in aqua regia (a mixture of hydrochloric and nitric acids) to create soluble salts. They always observed a small amount of a dark, insoluble residue. Joseph Louis Proust thought that the residue was graphite. The French chemists Victor Collet-Descotils, Antoine François, comte de Fourcroy, and Louis Nicolas Vauquelin also observed the black residue in 1803, but did not obtain enough for further experiments. In 1803, British scientist Smithson Tennant analyzed the insoluble residue and concluded that it must contain a new metal. Vauquelin treated the powder alternately with alkali and acids and obtained a volatile new oxide, which he believed to be of this new metal—which he named ptene, from the Greek word πτηνός ptēnós, "winged". Tennant, who had the advantage of a much greater amount of residue, continued his research and identified the two previously undiscovered elements in the black residue, iridium and osmium. He obtained dark red crystals by a sequence of reactions with sodium hydroxide and hydrochloric acid. He named iridium after Iris (Ἶρις), the Greek winged goddess of the rainbow and the messenger of the Olympian gods, because many of the salts he obtained were strongly colored. Discovery of the new elements was documented in a letter to the Royal Society on June 21, 1804.

Original word	Iris
Language of origin	Greek
Name source	Mytologi
Meaning	“Iris”
Naming The name is derived from Iris, the Greek goddess of the rainbow, because iridium's salts display many vivid colours.

CAS Number	7439-88-5
ChemSpider ID	22367
EC number	231-095-9
PubChem CID Number	23924