Symbol	Hf
Atomnummer	72
Gruppe	4 (Titangruppe)
Periode	6
Blok	d
Klassifikation	Overgangsmetal

Udseende	Steel gray
Farve	Grå

Antal protoner	72 p+
Antal neutroner	106 n0
Antal elektroner	72 e-

Fra Wikipedia, den gratis encyklopædiHafnium (opkaldt efter Hafnia; det latinske navn for København) er det 72. grundstof i det periodiske system, og har det kemiske symbol Hf. Under normale tryk- og temperaturforhold optræder dette overgangsmetal som et mørkt, stålgråt og skinnende metal. Hafnium er temmelig korrosionsbestandigt, og ligner i kemisk hendseende zirconium ganske meget, mens disse to stoffers fysiske egenskaber er vidt forskellige; eksempelvis har hafnium næsten dobbelt så stor massefylde som zirconium. Og med hensyn til evnen til at indfange neutroner, er omkring 600 gange bedre til dette end zirconium.

Fase ved STP	Fast
Massefylde	13.31 g/cm3
Atommasse	178.492 u

Smeltepunkt	2506 K 2232.85 °C 4051.13 °F
Kogepunkt	4876 K 4602.85 °C 8317.13 °F
Fordampningsvarme	661.07 kJ/mol

Elektronegativitet (Pauling Scale)	1.3
Elektronaffinitet	17.18 kJ/mol
Oxidationstrin	−2, 0, +1, +2, +3, +4 (an amphoteric oxide)
Ioniseringsenergier	658.5 kJ/mol 1440 kJ/mol 2250 kJ/mol 3216 kJ/mol

Elektronkonfiguration Kortfattet konfiguration	[Xe] 4f14 5d2 6s2
Elektronkonfiguration Fuld konfiguration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d2 6s2
Elektronkonfigurationsdiagram	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d2 6s2
Elektroner pr. Skal	2, 8, 18, 32, 10, 2
Valenselektroner	2
Valency-elektroner	4
Bohrs atommodel	Figur: Skaldiagram af Hafnium (Hf) atom.
Orbital diagram 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 6s

Forudsigelse	Dmitri Mendeleev (1869)
Opdagelse og første isolation	Dirk Coster, George de Hevesy (1922)
Opdagelse af hafnium In his report on The Periodic Law of the Chemical Elements, in 1869, Dmitri Mendeleev had implicitly predicted the existence of a heavier analog of titanium and zirconium. The X-ray spectroscopy done by Henry Moseley in 1914 showed a direct dependency between spectral line and effective nuclear charge. This led to the nuclear charge, or atomic number of an element, being used to ascertain its place within the periodic table. With this method, Moseley determined the number of lanthanides and showed the gaps in the atomic number sequence at numbers 43, 61, 72, and 75. The discovery of the gaps led to an extensive search for the missing elements. And the reappearance in 1922 of Urbain's claims that element 72 was a rare earth element discovered in 1911, Dirk Coster and Georg von Hevesy were motivated to search for the new element in zirconium ores.Hafnium was discovered by the two in 1923 in Copenhagen, Denmark, validating the original 1869 prediction of Mendeleev. It was ultimately found in zircon in Norway through X-ray spectroscopy analysis. The place where the discovery took place led to the element being named for the Latin name for "Copenhagen", Hafnia, the home town of Niels Bohr.

CAS Number	7440-58-6
ChemSpider ID	22422
EC number	231-166-4
PubChem CID Number	23986