What do Lewis dot structures represent?

Lewis dot structures represent the valence electrons of an element. These diagrams provide a visual way to understand how many valence electrons are available for bonding in a chemical compound. By using dots to represent these electrons, the structures help illustrate how atoms will bond with one another, forming molecules and compounds.

Valence electrons are crucial because they dictate how elements interact chemically. The arrangement and number of these electrons determine the bonding behavior of the atom; for instance, atoms will typically aim for a full outer electron shell, leading them to gain, lose, or share electrons.

The other options relate to different concepts in chemistry. For example, while chemical reactions encompass the changes that occur when substances interact, they do not focus specifically on valence electrons. Atomic mass deals with the mass of individual atoms, typically reflecting the total number of protons and neutrons in an atom's nucleus. Molecular weight, similarly, gives a measure of the mass of a molecule, derived from the atomic masses of its constituent atoms, and is not directly concerned with the distribution of valence electrons.