| Cr |
| Atomic Number |
24 |
| Atomic Mass |
51.9961 |
| Atomic radius |
0.117 |
| Ionization energy |
652 |
| Electronic config |
2,8,13,1 |
| Principal Valency |
+3 and +6 |
| Density g/cm3 |
7.14 |
| Melting point oC |
1907 |
| Boiling point oC |
2671 |
| Type of Element |
Metal |
| Electronegativity |
1.6 |
| Appearance |
Gray solid |
| Block |
d-block |
| Period |
4 |
| Group |
6 |
| No of Isotopes |
26 |
| Occurrence |
Combine form |
| Abundance in ppm |
122 |
| Year of Discovery |
1797 |
|
| INTRODUCTION |
| Chromium is a common element,with about 21st in natural abundance among the elements in crustal rocks.Many precious stones owe their colour to the presence of chromium compounds. |
| It can replace part of the aluminum or iron in many minerals,imparting to them their unique colors and it can take on a high polish.Its name is derive fromthe Greek word Chroma (colour) due to the various colour of its compounds. |
| EXTRACTION |
| OXIDATION STATES |
| +6,+5,+4,+3,+2,-1,-2 (Strongly acidic) |
| ELEMENT CATEGORY |
MAJOR SOURCE |
| Chromium Group |
Chromite |
| EXAMPLES OF COMPOUND PRESENT |
| Chromic oxide, Potassium dichromate, lead chromate |
| ECONOMIC IMPORTANCE |
| * Chromium makes up 10 percent or more of the final composition of the stainless steels. |
| * Due to its hardness,an alloy of chromium,cobalt and tungsten is used for high-speed metal-cutting tools. |
| * It is used extensively as a refractory due to its high melting point,its moderate thermal expansion and the stability of its crystalline structure. |
| * It serve as an important ingredient in several catalysts. |
|
