Q15P - Chemistry: Molecular Nature Of Matter And Change

Question

Rank the following elements in order of increasing 

(a) Atomic size: Ba, Mg, Sr 

(b) IE1: P, Na, Al 

(c) EN: Br, Cl, Se 

(d) No. of valence electrons: Bi, Ga, Sn

Step-by-Step Solution

Answer

a. Mg<Sr<Ba

b. Na<Al<P

c. Se<Br<Cl.

d. Ga<Sn<Bi.

Step 1: Atomic size

It’s basically called the atomic radius which states that it is the distance from the centre of the nucleus to the outermost shell. It follows different trends in period and group.

Step 2: Explanation for the following

a. The atomic size of the element increases down the group. All the given elements belong to the same group. Hence, increasing the order of atomic size is: Mg<Sr<Ba

b. As we move across a period then ionization energy increases. All the given elements belong to the same period, i.e., third. Hence, increasing the first ionization energy is Na<Al<P

c. Down the group electronegativity decreases and from left to right across the period EN increases. Hence, increasing EN is Se<Br<Cl.

d. The number of valence electrons in Bi (Z=83) is five, no. of the valence electron in Ga is 3 electrons, and no. of the valence electron in Sn is 4 electrons. Hence, increasing the order of no. of valance electrons are Ga<Sn<Bi.