Question

What is the maximum covalency of sulphur?

Answer 1

We know that covalency defines the number of electrons that are contributed by an atom while sharing electrons with others the same or different and this could be mutual sharing as a covalent bond. We have to say the same regarding the sulphur atom i.e., maximum number of bonds sulphur atoms can possibly make with other atoms or groups or substituents.

Complete answer:
Let us first discuss about chlorine element and covalency as follows:-
-Sulphur: It is a chemical element denoted by symbol ‘S’ and has atomic number 16. It belongs to group-16 which is also known as the chalcogen family and is the second-lightest of all the chalcogens available. Most of its properties are intermediate between oxygen (O) and Selenium (Se) elements.
-Since it belongs to chalcogen group i.e., group-16, it has only 6 electrons in its valence shell like all the other chalcogen elements and also its valency is -2 like others.
-Covalency: It refers to the number of electrons contributed by an atom while sharing electrons with others the same or different. This sharing is done mutually like a covalent bond.
-Maximum covalency is usually the maximum number of covalent bonds which an atom could form easily with other atoms. An atom can show maximum covalency upto its group number (especially for elements that have d-orbitals). For example: maximum covalency of sulphur is 6.
-Since sulphur has empty d-orbitals, its valence electrons can easily jump to the excited states and become unpaired for the purpose of bonding with other atoms or groups. Total number of valence electrons of sulphur is 6, so its maximum covalency will also be 6.
-Therefore the maximum covalency of sulphur is 6.

Note:
-Generally the second period elements have maximum covalency equal to their actual unpaired electrons. This is without any involvement of excitation as they are small in size and do not have any empty d-orbitals so as to jump electrons to the excited states.