Krom

Symbol	Cr
Atomnummer	24
Gruppe	6 (Kromgruppe)
Periode	4
Blok	d
Klassifikation	Overgangsmetal

Udseende	Silvery metallic
Farve	Sølv

Antal protoner	24 p+
Antal neutroner	28 n0
Antal elektroner	24 e-

Fra Wikipedia, den gratis encyklopædiKrom (i litteratur, herunder Kemisk Ordbog, også skrevet chrom) er det 24. grundstof i det periodiske system, og har det kemiske symbol Cr: Under normale temperatur- og trykforhold optræder dette overgangsmetal som et sølvhvidt, skinnende og temmelig hårdt metal med et højt smeltepunkt på 1907 grader celsius.

Fase ved STP	Fast
Massefylde	7.19 g/cm3
Atommasse	51.9962 u

Smeltepunkt	2180 K 1906.85 °C 3464.33 °F
Kogepunkt	2944 K 2670.85 °C 4839.53 °F
Fordampningsvarme	339.5 kJ/mol

Elektronegativitet (Pauling Scale)	1.66
Elektronaffinitet	65.21 kJ/mol
Oxidationstrin	−4, −2, −1, 0, +1, +2, +3, +4, +5, +6 (depending on the oxidation state, an acidic, basic, or amphoteric oxide)
Ioniseringsenergier	652.9 kJ/mol 1590.6 kJ/mol 2987 kJ/mol 4743 kJ/mol 6702 kJ/mol 8744.9 kJ/mol 15455 kJ/mol 17820 kJ/mol 20190 kJ/mol 23580 kJ/mol 26130 kJ/mol 28750 kJ/mol 34230 kJ/mol 37066 kJ/mol 97510 kJ/mol 105800 kJ/mol 114300 kJ/mol 125300 kJ/mol 134700 kJ/mol 144300 kJ/mol 157700 kJ/mol 166090 kJ/mol 721870 kJ/mol 761733 kJ/mol

Elektronkonfiguration Kortfattet konfiguration	[Ar] 3d5 4s1
Elektronkonfiguration Fuld konfiguration	1s2 2s2 2p6 3s2 3p6 3d5 4s1
Elektronkonfigurationsdiagram	1s2 2s2 2p6 3s2 3p6 3d5 4s1
Elektroner pr. Skal	2, 8, 13, 1
Outer shell electrons	1
Valence electrons (incl. d)	6
Valency-elektroner	2
Bohrs atommodel	Figur: Skaldiagram af Krom (Cr) atom.
Orbital diagram	1s 2s 2p 3s 3p 3d 4s

Opdaget	Louis Nicolas Vauquelin (1794)
Første isolation	Louis Nicolas Vauquelin (1797)
Opdagelse af krom Chromium minerals as pigments came to the attention of the west in the eighteenth century. On 26 July 1761, Johann Gottlob Lehmann found an orange-red mineral in the Beryozovskoye mines in the Ural Mountains which he named Siberian red lead. In 1770, Peter Simon Pallas visited the same site as Lehmann and found a red lead mineral that was discovered to possess useful properties as a pigment in paints. After Pallas, the use of Siberian red lead as a paint pigment began to develop rapidly throughout the region. Crocoite would be the principal source of chromium in pigments until the discovery of chromite many years later. In 1794, Louis Nicolas Vauquelin received samples of crocoite ore. He produced chromium trioxide (CrO3) by mixing crocoite with hydrochloric acid. In 1797, Vauquelin discovered that he could isolate metallic chromium by heating the oxide in a charcoal oven, for which he is credited as the one who truly discovered the element.

Original word	chroma
Language of origin	Greek
Name source	Egenskaber
Meaning	“Colour”
Naming The name is derived from the Greek word 'chroma', meaning color because it forms a variety of colorful compounds.

CAS Number	7440-47-3
ChemSpider ID	22412
EC number	231-157-5
PubChem CID Number	23976