Which sentence best describes a bond formed between two unlike atoms?
The correct answer and explanation is:
The best sentence to describe a bond formed between two unlike atoms is: “A polar covalent bond is formed when two atoms with different electronegativities share an electron pair, but the more electronegative atom attracts the electron pair more strongly.”
In chemical bonding, atoms form bonds to achieve a more stable electron configuration. Atoms can bond in different ways depending on their electronegativity, which is a measure of an atom’s ability to attract and hold onto electrons.
In the case of a polar covalent bond, the two atoms involved are typically nonmetals that differ in electronegativity. One atom has a stronger pull on the shared electrons, causing an uneven distribution of electron density. This results in a partial negative charge on the atom with higher electronegativity and a partial positive charge on the atom with lower electronegativity. For example, in a water molecule (H2O), the oxygen atom is more electronegative than the hydrogen atoms, so it pulls the shared electrons closer to itself, creating a dipole.
This unequal sharing of electrons distinguishes a polar covalent bond from a nonpolar covalent bond, where the electrons are shared more equally. A nonpolar covalent bond typically forms between two identical atoms, like in a molecule of oxygen (O2), where both atoms have the same electronegativity and share electrons evenly.
The polar nature of the bond influences the molecule’s overall properties. Molecules with polar covalent bonds often have higher boiling points, can dissolve in water, and exhibit dipole-dipole interactions, which are crucial in many biological processes.
In summary, a bond between unlike atoms that differ in electronegativity is best described as a polar covalent bond due to the unequal sharing of electrons.