Chapter 3, Problem 1IQ

Draw the four water molecules that can hydrogen-bond to this water molecule. Label the bonds and the partial negative and positive charges that account for the formation of these hydrogen bonds.

Summary Introduction

To draw: The four water molecules that can form hydrogen-bond to the given water molecule and label the bonds and the partial negative and positive charges that account for the formation of these hydrogen bonds.

Introduction: A water molecule is shaped like a ‘V’ that consists of an oxygen atom and two hydrogen atoms. Oxygen is more electronegative than hydrogen. Thus, the shared electrons in the O-H covalent bond are more attracted by the oxygen atom.

Answer to Problem 1IQ

Pictorial representation: Fig.1 represents the four water molecules that can form hydrogen-bond for the given water molecule and label the bonds and the partial negative and positive charges that account for the formation of these hydrogen bonds.

Fig.1: Four water molecules bind with one water molecule

Explanation of Solution

Electronegativity is the tendency of an atom in a molecule to attract electrons shared in a covalent bond. If one atom is more electronegative, the electrons would be more on the side of that atom. Oxygen is more electronegative than hydrogen. In a water molecule, there are two polar covalent bonds between oxygen and hydrogen. Hence, there are two regions of partial negative charge on oxygen and a partial positive charge on each hydrogen atom.

The partial negatively charged oxygen atom of a water molecule is attracted to the partial positively charged hydrogen of the other water molecule. As per Fig.1, atoms on the partial charged regions can bind to oppositely charged regions on other adjoining water molecules. There are four regions of partial charge in a water molecule. Thus, the central water molecule can form a hydrogen bonds with four other water molecules.