Question

Few general names are given along with their valence shell configuration. Mark the incorrect name.
(A) $n{{s}^{2}}n{{p}^{6}}$- Noble gases
(B) $n{{s}^{2}}n{{p}^{5}}$- Halogen
(C) $n{{s}^{1}}$- Alkali metals
(D) $n{{s}^{2}}n{{p}^{2}}$- Chalcogen

Answer 1

Hint: The highest occupied orbit is called the valence shell and the electrons present in this electronic shell are called valence electrons. The periodic The elements are placed in the periodic table in such a way that the number of valence electrons is equal to its group number on the Periodic table.

Complete step by step answer:
- The valence shell of an atom is its outermost orbital shell. Valence shell electrons have the highest energy and are hence most reactive. Valence electrons only take part in chemical reactions by gaining or losing electrons
- The noble gases are the sole non-transition-metal elements that have eight valence electrons in their neutral, state configuration. Halogens belong to group number 18. The noble gases have an electronic configuration $n{{s}^{2}}n{{p}^{6}}$.
- Elements of group 17 which include Fluorine, Chlorine, Bromine, Iodine, and Astatine are called halogens. These are one electron short of a cadence shell octet and are among the most reactive elements. The halogens have an electronic configuration $n{{s}^{2}}n{{p}^{5}}$.
- The alkali metals belong to group 1 and have one valence electron in their outermost shell. These elements tend to lose one electron to arrive at the lower shell valence octet. Due to the ability of alkali metals for losing electrons, they are positively charged atoms. The alkali has an electronic configuration $n{{s}^{1}}$.
- The elements of group 16 are called chalcogens. Chalcogens are also called the oxygen family. The elements in this group are two electrons short of a filled valence shell. Chalcogens have an electronic configuration $n{{s}^{2}}n{{p}^{4}}$.
The electronic configuration of chalcogens is $n{{s}^{2}}n{{p}^{4}}$, which is mentioned incorrectly in option D.

Thus, the correct option is D.

Note: Recall the group number of the elements to calculate the valence shell configuration. Helium is a noble gas element that shows the exception in the general trend of valence electrons with their group number. Helium being in group eight has two valence electrons, but it still has a fun outer shell-like all other noble gases.