Allotropes of phosphorus
Phosphorus exists in at least six allotropic forms which are all solids at room temperature. Anyhow, we will mention only three:
- White phosphorus
- Red phosphorus
- Black phosphorus
White phosphorus
- It is yellowish white substance.
- It is a waxy solid.
- It is a poisonous substance.
- It is volatile in nature.
- It is soluble in benzene and carbon disulphide.
- It is very reactive.
- It boils at 280°C and molecules of P4 are present in the vapours.
- When heated above 700°C, it dissociates to form P2molecules.
Structure of white phosphorus:
It has cubic structure in which P4 molecules occupy the corners of a tetrahedron. Each P4 molecules has a tetrahedral structure. Fig. (1.1)
Red phosphorus.
Preparation:
It is prepared by heating white phosphorus in the pressure of little I2 or sulphur as a catalyst up to 250°C in vacuum.
- It is poisonous but less than that of white phosphorus.
- It is less reactive than white phosphorus.
Structure of red phosphorus:
Red phosphorus is a combination of tetrahedral P4 units to give macromolecules. Fig (1.2)
Black phosphorus
Black phosphorus is made by heating red phosphorus to high temperature and pressure. It is the most stable form of phosphorus under ordinary condition.
Have you ever thought about writing an ebook or guest authoring on other sites? I have a blog centered on the same subjects you discuss and would really like to have you share some stories/information. I know my audience would value your work. If you are even remotely interested, feel free to shoot me an email.