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. |
|