Question

Consider the general valence electron configuration of ns²np⁵ and the following statements: 

(i) Elements with this electron configuration are expected to form -1 anions. 

(ii) Elements with this electron configuration are expected to have large positive electron affinities. 

(iii) Elements with this electron configuration are nonmetals. 

(iv) Elements with this electron configuration form acidic oxides.

Answer 1

Consider some examples

F has atomic number 9

Electronic configuration is 1s²2s² 2p⁵

Cl has atomic number 17

Electronic configuration is 1s² 2s²2p⁶3s² 3p⁵

If you notice these two elements , they have two s and five p electrons in outermost orbitals. Thus they have ns² np⁵ general electronic configuration.Where n is outermost orbit.These two elements are belong to group 17. They have 7 electrons in outermost orbit. They are also called halogens.Other main members are Bromine and iodine.

(i) This statement is correct. These elements have 7 electrons in outermost orbit hence they need one electron to complete their octet and form -1 anions.

For example

Cl + e Cl^-

(Ii) When these elements gain one electron they release large amount of energy.This energy is also called electron affinity. When energy is released we denote it by negative sign. Hence this statement is wrong.

(iii) This is correct statement.Yes they are considered as non metals.

They show non  metallic properties because they  have tendency to gain electron.

(iv) Oxides can be acidic basic ,neutral or amphoteric. Non metallic oxides  are acidic  in nature. Since they are non metals hence form acidic oxides.