Question

Most electronegative element is:
(A) F
(B) Cs
(C) He
(D) I

Answer 1

Hint: Try to recall that the non-metals have are more electronegative than metals and on going down the group on modern periodic table electronegativity of elements tends to decrease. Now, by using this you can easily find the correct option from the given ones.

Complete answer:
* It is known to you that electronegativity of an element is the tendency of its atom to attract the shared pair of electrons towards itself in a covalent bond.
* Now, coming to the question out of fluorine (F), caesium (Cs), helium (He) and iodine (I), fluorine is the most electronegative element.
* This happens because as per the definition of electronegativity, the higher the tendency of an atom to attract the shared pair of electrons, the higher is its electronegativity.
* As fluorine has the highest attraction for the shared pair of electrons in a covalent bond with any other element because of its small atomic radius and large nuclear charge, it is the most electronegative element in the modern periodic table.
* Inert gases are neither electropositive or electronegative as they already have a stable electronic configuration and they don’t accept, donate or share their electrons. So, electronegativity of helium and other inert gases is zero.
* Also, Caesium (Cs) is the most electropositive element due to its lowest ionization enthalpy.
Therefore, from above we can easily conclude that option A is the correct option to the given question.

Note: It should be remembered that although fluorine is the most electronegative element, still its electron affinity is less than that of chlorine. This happens due to the small size of fluorine. All the electrons in the atom repel the incoming electron significantly, this nullifies the effect of higher electronegativity of fluorine over chlorine.