Question

The hydrogen bonding is strongest in which one of the following sets?
A.) F-H--F
B.) O-H--S
C.) S-H--F
D.) F-H--O

Answer 1

Hint: To determine the strongest hydrogen bonding, we should be knowing the electronegativity of the element mentioned in the options. Knowing the position of the element in the periodic table, also gives an idea about the electronegativity.

Complete step-by-step answer:
The strength of the hydrogen bond depends upon the coulombic interaction between the electronegativity of the attached atom and hydrogen. Fluorine is the most electronegative element. So the F-H--F bond will be the strongest H bond.
So the correct option is Option A.

The high electronegativity of fluorine indicates that it has a high tendency to gain electrons from other elements with lower electronegativity.

Additional Information:
The electronegativity of oxygen is: 3.44
The electronegativity of fluorine is: 3.98
The electronegativity of sulphur is: 2.58

Fluorine is the most electronegative element because it has 5 electrons in its 2p orbital. The optimal electron configuration of the 2p orbital contains 6 electrons, so since fluorine is so close to ideal electron configuration, the electrons are held very tightly to the nucleus.

Note: We know that from top to bottom down the group electronegativity decreases. This is because the atomic number increases down a group, and thus there is an increased distance between the valence electrons and nucleus, or a greater atomic radius.
Across a period the electronegativity increases as we move from left to right.