18. lonic radii are
(1) Greater than the respective atomic radii of elements in general
(2) Greater than the respective atomic radii of electropositive elements
(3) Greater than the respective atomic radii of electronegative elements
(4) Less than the respective atomic radii of electronegative elements
Plz give detailed explaination....
Answers
Answer:
The ionic radius is the distance between the nucleus and the electron in the outermost shell of an ion.
Explanation:
When an atom loses an electron to form a cation, the lost electron no longer contributes to shielding the other electrons from the charge of the nucleus; consequently, the other electrons are more strongly attracted to the nucleus, and the radius of the atom gets smaller.
When an electron is added to an atom, forming an anion, the added electron repels other electrons, resulting in an increase in the size of the atom.
The trend observed in size of ionic radii is due to shielding of the outermost electrons by the inner-shell electrons so that the outer shell electrons do not “feel” the entire positive charge of the nucleus.