# Which temperature is the beta sulphur stable at?

Below 369 K alpha sulphur is stable and above this it transforms into beta sulphur. At 369K both the forms are stable.

## The Allotropes of Sulphur

Sulphur exists in a variety of allotropes,  the two most appropriate ones: of sulphur-yellow rhombic sulphur (α-sulphur) and the monoclinic (β-sulphur). The most intriguing characteristic is their thermal stability; the allotropes of sulphur are interconvertible, i.e. rhombic sulphur becomes monoclinic sulphur when heated above 369K.

• 369K is called transition temperature because both the allotropes of sulphur are stable at this temperature.
• In other words, we can conclude that α sulphur is stable below 369K and it becomes β-sulphur above that temperature.
• Rhombic and monoclinic sulphur, both have S8 molecules.
• The alternative packing of S8 molecules gives different crystal structures.