Crom
24
Cr
Grup
6
Període
4
Bloc
d
Protons
Electrons
Neutrons
24
24
28
Propietats Generals
Nombre atòmic
24
Massa atòmica
51,9961
Nombre de massa
52
Categoria
Metalls de transició
Color
Plata
Radioactiu
No
From the Greek word chroma, color
Estructura cristal·lina
Cos cúbic centrat
Història
In 1797, Louis Nicolas Vauquelin received samples of crocoite ore.
In 1798, Vauquelin discovered that he could isolate metallic chromium by heating the oxide in a charcoal oven, making him the discoverer of the element.
Vauquelin was also able to detect traces of chromium in precious gemstones, such as ruby or emerald.
In 1798, Vauquelin discovered that he could isolate metallic chromium by heating the oxide in a charcoal oven, making him the discoverer of the element.
Vauquelin was also able to detect traces of chromium in precious gemstones, such as ruby or emerald.
Electrons per capa
2, 8, 13, 1
Configuració electrònica
[Ar] 3d5 4s1
Chromium oxide was used by the Chinese in the Qin dynasty over 2,000 years ago
Propietats Físiques
Fase
Sòlid
Densitat
7,15 g/cm3
Punt de fusió
2180,15 K | 1907 °C | 3464,6 °F
Punt d'ebullició
2944,15 K | 2671 °C | 4839,8 °F
Entalpia de fusió
20,5 kJ/mol
Entalpia de vaporització
339 kJ/mol
Capacitat tèrmica específica
0,449 J/g·K
Abundància a l'escorça terrestre
0,014%
Abundància a l'univers
0,0015%
Crèdits de les imatges: Wikimedia Commons (Alchemist-hp)
High purity chromium crystals, produced by chemical transport reaction through decomposition of chromium iodides, as well as a high purity chromium cube for comparison
Número CAS
7440-47-3
Número CID de PubChem
23976
Propietats Atòmiques
Radi atòmic
128 pm
Radi covalent
139 pm
Electronegativitat
1,66 (Escala de Pauling)
Potencial d'ionització
6,7665 eV
Volum atòmic
7,23 cm3/mol
Conductivitat tèrmica
0,937 W/cm·K
Estats d'oxidació
-2, -1, 1, 2, 3, 4, 5, 6
Aplicacions
Chromium is used to harden steel, manufacture stainless steel, and form many useful alloys.
It is mostly used in plating to produce a hard, beautiful surface and to prevent corrosion.
The metal is also widely used as a catalyst.
Chromium compounds are valued as pigments for their vivid green, yellow, red and orange colors.
It is mostly used in plating to produce a hard, beautiful surface and to prevent corrosion.
The metal is also widely used as a catalyst.
Chromium compounds are valued as pigments for their vivid green, yellow, red and orange colors.
In larger amounts, chromium can be toxic and carcinogenic
Isòtops
Isòtops estables
50Cr, 52Cr, 53Cr, 54CrIsòtops inestables
42Cr, 43Cr, 44Cr, 45Cr, 46Cr, 47Cr, 48Cr, 49Cr, 51Cr, 55Cr, 56Cr, 57Cr, 58Cr, 59Cr, 60Cr, 61Cr, 62Cr, 63Cr, 64Cr, 65Cr, 66Cr, 67Cr