Question

Match the valence electrons with the elements K, P, Ar, B, CI, Si (3.0 marks) Valence electrons 4 Element (b) Calculate the oxidation number Sulphur in (NH4),SO4 Nitrogen in Nitric acid

Answer 1

(a) Since above all the element belongs to s and p block elements.So you can determine the valence electrons by filling the atomic number in different shell theory given by bohr's like K shell,L shell,M shell,etc. This filling of electrons take place by satisfying duplet and octet rule.

For example Atomic number of Pottasium is 19 so the electrons will be filled like this- Kshell-2,L shell-8,M shell-8,N shell-1. So the last shell is N shell and it consists of 1 electron.Therefore valence electron in Pottasium is 1.

Similarly Phosphorous atomic number 15.So, 2,8,5 i.e. 5 valence electrons.

Argon-atomic number 18.So 2,8,8.That is 8 valence electrons.

Boron-atomic number 5. So 2,3 i.e. 3 valence electrons

Chlorine-atomic number 17. So, 2,8,7 i.e. 7 valence electrons

SILICON-atomic number 14.So ,2,8,4 ie. 4 valence elctrons.Hence,it is the correct answer.

(b)