Χρώμιο

24
Cr
Ομάδα
6
Περίοδος
4
Τομέας
d
Πρωτονίων
Electrons
Νετρονίων
24
24
28
General Properties
Ατομικός Αριθμός
24
Ατομικό βάρος
51,9961
Mass Number
52
Κατηγορία
Στοιχεία μετάπτωσης
Χρώμα
Silver
Radioactive
Όχι
From the Greek word chroma, color
Κρυσταλλικό σύστημα
Body Centered Cubic
Ιστορία
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.
Electrons per shell
2, 8, 13, 1
Ηλεκτρονική διαμόρφωση
[Ar] 3d5 4s1
Cr
Chromium oxide was used by the Chinese in the Qin dynasty over 2,000 years ago
Physical Properties
Phase
Στερεά
Πυκνότητα
7,15 g/cm3
Σημείο τήξης
2180,15 K | 1907 °C | 3464,6 °F
Σημείο βρασμού
2944,15 K | 2671 °C | 4839,8 °F
Heat of Fusion
20,5 kJ/mol
Heat of Vaporization
339 kJ/mol
Ειδική θερμοχωρητικότητα
0,449 J/g·K
Abundance in Earth's crust
0,014%
Abundance in Universe
0,0015%
High
Image Credits: 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
CAS Number
7440-47-3
PubChem CID Number
23976
Atomic Properties
Ατομική ακτίνα
128 pm
Ομοιοπολική ακτίνα
139 pm
Ηλεκτραρνητικότητα
1,66 (Κλίμακα Pauling)
Ionization Potential
6,7665 eV
Atomic Volume
7,23 cm3/mol
Θερμική αγωγιμότητα
0,937 W/cm·K
Oxidation States
-2, -1, 1, 2, 3, 4, 5, 6
Applications
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.
In larger amounts, chromium can be toxic and carcinogenic
Ισότοπα
Stable Isotopes
50Cr, 52Cr, 53Cr, 54Cr
Unstable Isotopes
42Cr, 43Cr, 44Cr, 45Cr, 46Cr, 47Cr, 48Cr, 49Cr, 51Cr, 55Cr, 56Cr, 57Cr, 58Cr, 59Cr, 60Cr, 61Cr, 62Cr, 63Cr, 64Cr, 65Cr, 66Cr, 67Cr