Question

The correct order of ionic radii of the following
species is
(1) Sez->> Br > 02-> F-
(2) l-> Sez-> O2- > Br > F-
(3) S02-> > Br > F-> C2-
(4) 1-> Se2- > Br > 02-> F-
​

Answer 1

Answer:

Ionic radii top to bottom decreases

Answer 2

Answer:

(4)

Explanation:

Firstly, atomic radius and ionic radius trends are the same.

Hence, the ionic radius values increase down the group from top to bottom and decrease across a period from left to right.

One more thing to keep in mind is that the anion (negative ion) has atomic radius that is higher than that of the neutral atom. The atomic radius of the cation is lesser than that of the neutral atom.

I've inserted a picture of the periodic table along with this answer for better understanding and reference.

According to the trends mentioned above,

• I- will have the highest ionic radius (when comparing the elements in the options, it is the element that is at the bottom-most position and there are no elements mentioned that are to its right)
• Se2- has the next highest (in comparison to Br, Se comes before Br in the periodic table and according to the trends the atomic radius decreases across a period from left to right, meaning that Se has higher radius than Br)
• O2- has more radius than F- (once again, O arrives before F in the periodic table)

Hopefully, this answer helps you. Please feel free to comment and ask for further help if you need any.