Each of the pictures (a)–(d) represents one of the following substances at 25 °C: sodium, chlorine, iodine, sodium chloride. Which picture corresponds to which substance? (a)

Key Concepts

Diatomic Molecules

Diatomic molecules consist of two atoms, which can be of the same or different elements. In the context of the question, chlorine (Cl2) is a diatomic molecule formed by two chlorine atoms bonded together. Understanding the structure of diatomic molecules is crucial for identifying substances represented in molecular models.

States of Matter

At 25 °C, substances can exist in different states: solid, liquid, or gas. Chlorine is a gas at this temperature, which influences its molecular representation. Recognizing the state of matter helps in understanding the arrangement and behavior of molecules in different substances, such as the gaseous nature of chlorine depicted in the image.

Molecular Representation

Molecular representation uses models to depict the arrangement and bonding of atoms within a molecule. The image shows green diatomic molecules, indicating the presence of chlorine gas. Familiarity with molecular models aids in visualizing and identifying chemical substances based on their structural characteristics.