Chrom
24
Cr
Skupina
6
Perioda
4
Blok
d
Protony
Elektrony
Neutrony
24
24
28
Hlavní vlastnosti
Atomové číslo
24
Atomová hmotnost
51,9961
Hmotnostní číslo
52
Kategorie
Přechodné kovy
Barva
Stříbrná
Radioaktivní
Ne
Z řeckého slova chroma, barva
Krystalografická soustava
Kubická prostorově centrovaná
Historie
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.
Elektronů v obalu
2, 8, 13, 1
Elektronová konfigurace
[Ar] 3d5 4s1
Chromium oxide was used by the Chinese in the Qin dynasty over 2,000 years ago
Fyzické vlastnosti
Skupenství
Pevná
Hustota
7,15 g/cm3
Teplota tání
2180,15 K | 1907 °C | 3464,6 °F
Teplota varu
2944,15 K | 2671 °C | 4839,8 °F
Skupenské teplo tání
20,5 kJ/mol
Skupenské teplo varu
339 kJ/mol
Měrná tepelná kapacita
0,449 J/g·K
Hojnost v zemské kůře
0,014%
Hojnost ve vesmíru
0,0015%
Autorská práva obrázku: 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
Číslo CAS
7440-47-3
PubChem CID číslo
23976
Atomové vlastnosti
Atomový poloměr
128 pm
Kovalentní poloměr
139 pm
Elektronegativita
1,66 (Paulingova stupnice)
Ionizační potenciál
6,7665 eV
Molární objem
7,23 cm3/mol
Tepelná vodivost
0,937 W/cm·K
Oxidační čísla
-2, -1, 1, 2, 3, 4, 5, 6
Aplikace
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
Izotopy
Stabilní izotopy
50Cr, 52Cr, 53Cr, 54CrNestabilní izotopy
42Cr, 43Cr, 44Cr, 45Cr, 46Cr, 47Cr, 48Cr, 49Cr, 51Cr, 55Cr, 56Cr, 57Cr, 58Cr, 59Cr, 60Cr, 61Cr, 62Cr, 63Cr, 64Cr, 65Cr, 66Cr, 67Cr