# What are the elemental states of phosphorus, selenium, sulfur, and carbon?

Dec 2, 2016

$P , S e , S ,$ and $C$ tend to be non-molecular........

#### Explanation:

Carbon can form a high energy ${C}_{2}$ molecule, as well as the non-molecular graphite form and diamond form. Diamond and graphite differ in the respect of structure: graphite is non-molecular in 2 dimensions, whereas diamond is non-molecular in 3 dimensions. You should also look at $\text{buckminsterfullerene, } {C}_{60}$; if you can describe the shape of a football, you can describe this molecule.

Phosphorus also has several allotropic forms. It can form a highly reactive ${P}_{4}$ molecule, i.e. $\text{white phosphorus}$, which must be stored under water because of the strain imposed by the ${P}_{4}$ tetrahedron; the material ignites in air. Red phosphorus, has a similar structure, however, in this allotrope there are no discrete molecules. There are a few reactions where red phosphorus can be used in place of white phosphorus provided that reaction times are extended.

Sulfur has several allotropic forms. $\text{Flowers of sulfur}$, a bright yellow powder, is what is normally supplied to laboratories; this is the ${S}_{8}$ molecule, and is as soluble as a brick.

Selenium is again non-molecular and has 2-3 allotropes, i.e. black and red selenium.

At undergraduate and A level, the so-called allotropes of carbon, and phosphorus should be committed to memory.