Question

Arrange the following as per the instruction in the brackets -

[i] $He,Ar,Ne$ [Increasing order of the number of electron shells]

[ii] $Na,Li,K$ [Increasing ionisation energy],

[iii] $F,Cl,Br$ [Increasing electronegativity]

[iv] $Na,K,Li$ [Increasing atomic size].

Answer 1

(i) $He<Ne<Ar$ [When we move down in group number of electron shells increases] $\{r=\frac{r_0{n}^2}{2}\}$

(ii) $K<Na<Li$ [On going down the group atomic size gradually increases consequently attraction between nucleus and electron decreases hence low energy is required to remove electron from outermost shell so I.e. decreases]

(iii) $Br<Cl<F$ [Because the increased number of energy level puts the outer electrons very far away from the pull of nucleus]

(iv) $Li<Na<K$ [We know that $⟹r=\frac{r_0{n}^2}{2}$ when number of shell atomic radius increase]