Published On: Fri, May 26th, 2017

Chromium- All about Chromium and its Atomic Characteristics

Chromium

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
It is obtain by reducing it’s oxide
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.

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