Question

Arrange these ions according to ionic radius.

Largest radius to Smallest radius

Answer Bank : Na^+ , F^- , Mg^2+ , N^3- , O^2-

Answer 1

We know that ions with negative charge are greater in size compared to ions with positive charge. This is due to the inter-electronic repulsion between the electrons. More the negative charge greater is the size of the ions. On the other hand more the positive charge smaller is the ions.

Among the given ions all are isoelectronic. For this case to determine the ionic radius we have to consider the number protons in each case. Higher the no. of proton smaller the ionic radius. In case Mg​​​+2 ion it has highest no. of proton so it's ionic radius is the smallest compared to other ions. This is due to the strong electrostatic attraction between nucleus and the outer electron. For the other ions electrostatic attraction decreases due to less charge(no. of proton) in the nucleus and hence the radius increased.

Answer to the problem Electron 10e 10e 10ě 10 10é Proton 12 10 9 8 7 Tonie radius trend w yo2 Fy Na > Mg" + 2.