a) Both fluorine and chlorine are in the same group in periodic table.
b) They differ in their atomic radius and electronegativity.
c) Because they have the similar number of electrons in their outer shell.
Explanation:
a) Electronic configuration of chlorine and fluorine are similar because these two elements belong to the same group number 17 of the periodic table as they have the same number of electrons in their outer or valence shell. These are called as halogens and are highly reactant.
F - 1s2,2s2,2p5 (9)
Cl- 1s2,2s2,2p6,3s2,3p5 (17)
b. The atomic radius of chlorine and fluorine are different because fluorine is on top of chlorine in the group. We know as we go down in a group in the periodic table the atomic radius increases though they have the same number of electrons in their outer shell electronegativity decreases. Fluorine is the most electronegative element of the periodic table.
c) Iodine and bromine are also the members of group 17, although their atomic numbers are different they have same valence electrons as chlorine and fluorine.
Iodine electronic configuration: 1s2,2s2,2p6,3s2.........4d10,5s2,5p5.
Bromine electronic configuration: 1s2,2s2,2p6,3s2,........3d10,4s2,4p5
Chlorine electronic configuration: 1s2,2s2,2p6,3s2,3p5
We can observe the outer shell having same number of electrons.
