Question

Describe the structure of a water molecule.

Short answer

A water molecule is composed of two hydrogen atoms and one oxygen atom with a bent shape and is polar.

Step-by-step solution

Identify Molecule Composition

Recognize that a water molecule consists of three atoms: two hydrogen atoms (H) and one oxygen atom (O).

Understanding Atomic Bonds

Explain that each hydrogen atom forms a covalent bond with the oxygen atom, sharing electrons. This gives the molecule its stable structure.

Molecular Geometry

Note that the water molecule has a bent shape due to the two hydrogen-oxygen bonds and the lone pairs of electrons on the oxygen atom. This results in a bond angle of approximately 104.5 degrees.

Polarity of Water Molecule

Describe that because of the bent shape and the difference in electronegativity between oxygen and hydrogen, the water molecule is polar. The oxygen side is slightly negative, and the hydrogen side is slightly positive.

Key concepts

molecular composition

The water molecule is composed of three atoms: two hydrogen atoms and one oxygen atom. This atomic arrangement is represented by the chemical formula H₂O. The oxygen atom lies at the center of the molecule, with the two hydrogen atoms bonded to it. Understanding this basic composition is crucial for diving deeper into the properties and behavior of water. Each hydrogen atom is bonded to the oxygen atom, forming a molecule that is essential for life as we know it.

covalent bonds

Within a water molecule, hydrogen and oxygen atoms are linked by covalent bonds. A covalent bond occurs when two atoms share electrons, creating a stable balance. In H₂O, each hydrogen atom shares its electron with the oxygen atom, resulting in two covalent bonds. The shared electrons allow the molecule to remain stable and hold together tightly. This sharing of electrons is a fundamental aspect of the chemical bonding process and is key to the molecule’s overall stability.

molecular geometry

The geometry of the water molecule plays a significant role in its unique properties. Water has a bent or V-shaped structure due to the two hydrogen-oxygen bonds and the lone pairs of electrons on the oxygen atom. The angle between the hydrogen atoms is approximately 104.5 degrees. The bent shape is caused by the repulsion between the lone pairs of electrons on the oxygen, pushing the hydrogen atoms closer together. This geometric configuration is essential in understanding why water behaves the way it does.

polarity

Water's polarity is a defining characteristic that explains many of its behaviors. Due to the bent molecular shape and the difference in electronegativity between oxygen and hydrogen, the water molecule is polar. Electronegativity is the tendency of an atom to attract electrons. Oxygen is more electronegative than hydrogen and pulls shared electrons closer to itself. This causes a partial negative charge near the oxygen atom and a partial positive charge near the hydrogen atoms. The result is a polar molecule with a dipole moment, leading to strong intermolecular attractions like hydrogen bonds. This polarity is why water is such a good solvent and has high surface tension.