In the structure of liquid water, what name is given to the attractive force that occurs between neighboring water molecules?

Introduction / Context:
Water has many unusual properties, such as a relatively high boiling point and surface tension, which are crucial for life. These properties arise largely from the special interactions between water molecules, not just within a single molecule. Inside each water molecule, the O H bonds are polar covalent, but between different water molecules there is a specific intermolecular attraction known as hydrogen bonding. This question asks you to name the bond or interaction between neighboring water molecules.

Given Data / Assumptions:
- A water molecule has the formula H2O and bent shape. - The O H bonds inside one water molecule are polar covalent bonds. - Neighboring water molecules attract each other strongly compared to many other small molecules. - We are interested in the interaction between different water molecules, not within a single molecule.

Concept / Approach:
Hydrogen bonding is a special type of strong dipole dipole interaction that occurs when hydrogen is covalently bonded to a very electronegative atom such as oxygen, nitrogen, or fluorine, and is then attracted to a lone pair on another electronegative atom in a nearby molecule. In water, the oxygen atom is highly electronegative and pulls electron density away from the hydrogen atoms, making them partially positive. These partially positive hydrogens are strongly attracted to lone pairs on the oxygen atoms of neighboring water molecules, creating hydrogen bonds.

Step-by-Step Solution:
Step 1: Recognise that within a single water molecule, each O H bond is a polar covalent bond because electrons are shared unevenly between oxygen and hydrogen. Step 2: Understand that the water molecule has a bent shape, leading to an overall molecular dipole with a partially negative region near oxygen and partially positive regions near hydrogen. Step 3: Between molecules, the partially positive hydrogen of one water molecule is attracted to the lone pair electrons on the partially negative oxygen of another water molecule. Step 4: This strong, directional attraction is called a hydrogen bond, a specific type of intermolecular force. Step 5: Hydrogen bonds are much weaker than covalent bonds within a molecule but stronger than many other intermolecular forces, which explains water unusual physical properties. Step 6: Therefore, the correct name for the bond between water molecules is a hydrogen bond.

Verification / Alternative check:
Evidence for hydrogen bonding in water includes its abnormally high boiling point compared to other similar sized molecules like H2S, and its high specific heat capacity. These properties cannot be explained by simple polar interactions alone and require stronger intermolecular forces. Structural studies and theoretical calculations confirm that each water molecule can form hydrogen bonds to several neighbours, producing a network in the liquid and a lattice in ice. These observations strongly support the conclusion that the intermolecular attraction in water is hydrogen bonding.

Why Other Options Are Wrong:
Option A refers only to general polar interactions and does not capture the specific, stronger hydrogen bond nature of water intermolecular forces. Option B mentions a polar covalent bond between separate water molecules, which is incorrect because covalent bonds are within molecules, not between them. Option D claims that none of the options apply, which is wrong because hydrogen bonding is the standard textbook explanation for water intermolecular attraction.

Common Pitfalls:
Students often confuse the polar covalent O H bonds inside the water molecule with the hydrogen bonds between molecules. Another common error is to think that hydrogen bonding is the same as covalent bonding or that it requires hydrogen alone without considering the electronegative partner. To avoid these mistakes, remember that hydrogen bonds are intermolecular forces that involve a hydrogen atom already bonded to an electronegative atom and interacting with a lone pair on another electronegative atom.

Final Answer:
The correct answer is: A hydrogen bond between the hydrogen of one molecule and the oxygen of another.