Suppose an electron is transferred from a potassium atom to an unknown halogen atom. For which of the following halogen atoms would this process require the least amount of energy? A. Cl
B. Br
C. I

Cl

Explanation:

Electronegativity is the ability of an electron to attract electrons.

Now, due to the fact that halogens need just one more electron to become stable in their outermost shell, it means all halogens are electronegative.

However, the smaller the atomic number, the bigger the charge density and thus the more electronegative.

Thus, it is the halogen element with the highest atomic number further down the periodic table that will have the least electro negativity and thus require highest amount of energy to attract other electrons.

Thus, since chlorine (Cl) has the least atomic number of 17, then it means that it will be the one that will easily accept the electrons the most from other elements. Therefore the process of transferring electrons from potassium to chlorine will take the least amount of energy.