Question

Which element has the greatest tendency to lose electrons?
A) F
B) S
C) Fr
D) Be

Answer 1

Hint: The tendency of losing electrons is known as ionization and this tendency is known as electro positivity. The electro positivity tendency of any element is its ability to lose electrons from its outermost orbital and form cation. For this question we need to know the trend of electropositivity across the period and down the group.

Complete answer:
Let us first know what electropositivity is. It is the tendency of an element to lose electrons and form cations. It is also known as the metallic character. It is known so because metals have the tendency to lose electrons and form cations whereas non-metals have the tendency to gain electrons and form anions. More the electropositivity of the metal, more easily it will lose electrons from its outermost orbit.
The process of losing electrons to form cations is known as Ionization, hence lower the ionization energy, more easily can the electron be removed from the orbital.
The ionization enthalpy/energy, across the period (left to right) increases. As we move from left to right the metallic character decreases and non-metallic character increases. Hence, it becomes difficult to lose an electron as we move across the period. Therefore, the s-block elements were found to have the highest electropositive tendency. As we move from left to right, the no. of electrons increases, but the no. of orbitals remains the same. Hence the effective nuclear charge increases, the electrons are very well bonded to the nucleus. Because of this the electron losing tendency decreases.
As we move down the group, the electropositivity increases, i.e. the ionization enthalpy decreases. Both, the electropositivity and the metallic character increases down the group. As we move down the group the size of the atom increases with the increasing no. of electrons. The shielding also increases, because of this the electrons are loosely bound to the nucleus. It was found that group I elements have the highest electropositivity, and as we move down the group I, the tendency increases.
In this question, out of the given options only Fr belongs to the Group I and is also of the biggest size in that group. Be belongs to group II and has a smaller size than Fr.

Hence Option C is the correct answer.

Note:
The non-metals that have the tendency to gain electrons are said to be electronegative. As we move across the period, the electropositive character decreases and electronegative character increases. Fluorine that belongs to the group XVII of the periodic table is the most electronegative.