6 The water molecule has a dipole with the negative portion A) localized between the hydrogen atoms. B) pointing toward the oxygen atom. C) localized on one of the hydrogens. D) pointing from the oxygen through the hydrogen atoms. E) surrounding the molecule. 9 ? 12 B 5 D A 3 E 3 Question 20 (4 points)
The Correct Answer and Explanation is :
The correct answer to the question is B) pointing toward the oxygen atom.
Explanation:
Water (H₂O) is a polar molecule due to its bent structure and differences in electronegativity between oxygen and hydrogen atoms. Oxygen is more electronegative than hydrogen, meaning it has a stronger attraction for the shared electrons in the O-H bonds. This causes the oxygen atom to acquire a partial negative charge (δ-) and the hydrogen atoms to acquire partial positive charges (δ+).
In a water molecule, the oxygen atom is highly electronegative and pulls the shared electrons towards itself. This results in the oxygen end of the molecule becoming slightly negative, and the hydrogen end becoming slightly positive. The distribution of charge within the molecule creates what is known as a dipole moment. The dipole moment points from the partial positive charge on the hydrogens to the partial negative charge on the oxygen.
The dipole refers to the separation of positive and negative charges within the molecule. In water, the dipole is oriented such that the negative pole (the electron-rich oxygen atom) attracts the positive poles (the hydrogen atoms), creating a polar structure. This is why the dipole points toward the oxygen atom (answer choice B).
In addition to the dipole moment, this polarity plays a key role in water’s unique properties, such as its high boiling point, surface tension, and its ability to dissolve many ionic compounds. The hydrogen bonds that form between water molecules are a direct result of these dipoles.
The other options are incorrect for the following reasons:
- A) localized between the hydrogen atoms: The dipole is not between the hydrogen atoms but rather pointing from the hydrogen atoms toward the oxygen.
- C) localized on one of the hydrogens: The dipole is not localized on a hydrogen atom but distributed across the molecule.
- D) pointing from the oxygen through the hydrogen atoms: The dipole points toward the oxygen atom, not from it.
- E) surrounding the molecule: While water molecules interact with each other due to their dipole, the dipole itself is internal and directed from the hydrogen atoms toward the oxygen.
Visual Representation:
Let me generate an image to visually show the molecular structure of water and its dipole.
Here is an illustration of the water molecule (H₂O) showing the dipole moment pointing toward the oxygen atom, as discussed. You can see the oxygen atom (in red) at the center, with the hydrogen atoms (in white) and the dipole arrow indicating the direction from the hydrogens to the oxygen. This visual highlights the polar nature of the water molecule.
