What do Lewis structures represent?

Lewis structures primarily represent the valence electrons of atoms within a molecule. Valence electrons are crucial because they are the electrons involved in forming chemical bonds and determining the reactivity of the atom. Lewis structures illustrate how these electrons are shared or transferred between atoms to form bonds, using dots to represent the valence electrons and lines to indicate shared pairs of electrons.

In a Lewis structure, the placement of these electrons illustrates the overall connectivity and arrangement of atoms in a molecule, providing insight into its structure and bonding behavior. This visual representation helps to predict geometric shapes, bond angles, and the overall stability of the compound.

Other options such as the number of protons or the arrangement of electrons in the nucleus do not pertain to Lewis structures, as they focus more on the atomic nucleus and electron cloud rather than the chemical bonding and interactions that Lewis structures specifically address. Thus, option C accurately captures the essence of what Lewis structures depict in the context of chemistry.