What allows water to form hydrogen bonds?
A.
the V-shape of the molecule
B.
two pairs of unbonded electrons
C.
two single bonds to hydrogen atoms
D.
differences in electronegativity between atoms
MY ANSWER IS B
To understand which option allows water to form hydrogen bonds, let's break down the characteristics of water. The water molecule (H2O) consists of two hydrogen atoms and one oxygen atom. The oxygen atom is more electronegative than the hydrogen atoms, resulting in an uneven distribution of electron density within the molecule.
Hydrogen bonding occurs when a hydrogen atom that is covalently bonded to a highly electronegative atom (like oxygen, nitrogen, or fluorine) is attracted to another electronegative atom in a nearby molecule. In the case of water, the oxygen atom in one water molecule forms a hydrogen bond with a hydrogen atom in a neighboring molecule.
Now let's examine each option to determine which one allows water to form hydrogen bonds:
A. The V-shape of the molecule: The V-shape of the water molecule (with the oxygen atom at the vertex and the hydrogen atoms at the ends) is due to the two lone pairs of electrons on the oxygen atom. While the V-shape is important for the overall structure of water, it does not directly contribute to hydrogen bonding.
B. Two pairs of unbonded electrons: This option refers to the two lone pairs of electrons on the oxygen atom of the water molecule. These lone pairs create regions of high electron density, which allow water to form hydrogen bonds. So, this option is correct.
C. Two single bonds to hydrogen atoms: This statement describes the covalent bonds between the oxygen atom and the two hydrogen atoms in water. While these bonds are crucial for water's molecular structure, they are not directly responsible for hydrogen bonding.
D. Differences in electronegativity between atoms: This option correctly describes one of the conditions required for hydrogen bonding. The difference in electronegativity between oxygen and hydrogen makes oxygen partially negative and hydrogen partially positive, enabling them to attract each other through hydrogen bonding.
In conclusion, options B (two pairs of unbonded electrons) and D (differences in electronegativity between atoms) both contribute to water's ability to form hydrogen bonds. Therefore, your answer of B is correct.