Draw a Lewis structure that represents a hydrogen molecule (H2) and show the relative polarities of the atoms (with partial charges δ+ and δ–), if any.
The Correct Answer and Explanation is:
Correct Answer:
Lewis Structure of Hydrogen Molecule (H₂):
CopyEditH—H
Each hydrogen atom shares one electron, forming a single covalent bond. There are no lone pairs in this molecule.
Polarity (Partial Charges):
Since both atoms are identical hydrogen atoms, the electrons in the bond are shared equally. Therefore, there are no partial charges (δ+ or δ−) on either hydrogen atom.
Polarity: Nonpolar molecule
Partial Charges: None (No δ+ or δ−)
Explanation:
A hydrogen molecule (H₂) is the simplest diatomic molecule, composed of two hydrogen atoms. Each hydrogen atom has one electron in its 1s orbital. When two hydrogen atoms come close enough, they can share their single electrons to form a covalent bond, resulting in a more stable configuration—akin to a helium atom, which has two electrons.
In the Lewis structure of H₂, this bond is depicted as a single line (H—H) between the two hydrogen atoms. Each hydrogen atom “feels” as if it has two electrons around it, satisfying the duet rule (the equivalent of the octet rule for hydrogen).
When evaluating polarity, we consider the electronegativity of the atoms involved. Electronegativity is a measure of how strongly an atom attracts electrons in a bond. If two atoms have different electronegativities, the shared electrons are pulled more toward the more electronegative atom, creating partial charges (δ+ and δ−), and the molecule is said to be polar.
However, in the case of H₂, both atoms are hydrogen—they have the same electronegativity (2.1 on the Pauling scale). As a result, the shared electrons are equally attracted to both nuclei. There is no unequal distribution of electron density, meaning no partial charges form.
Therefore, the hydrogen molecule is nonpolar, and neither atom carries a δ+ or δ− partial charge. It is a symmetrical, nonpolar covalent molecule, and one of the most basic examples used in chemistry to illustrate covalent bonding and molecular symmetry.
