What structural representation shows valence electrons in an atom?

The Lewis dot structure is the correct choice because it specifically represents the valence electrons of an atom by using dots placed around the chemical symbol of the element. Each dot corresponds to a valence electron, allowing for a visual representation of how these electrons are arranged. This is particularly useful for understanding chemical bonding and the reactivity of different elements, as it highlights how atoms may share or transfer electrons to form bonds. This method is foundational in chemistry as it provides insights into molecular structure and behavior based on electron configuration.

The other options, while useful in their own contexts, do not serve the same specific purpose. The ball and stick model illustrates the spatial relationships and angles between atoms in a molecule but does not focus on valence electrons. The space-filling model represents the size and shape of molecules more accurately but similarly lacks focus on individual valence electrons. The line angle structure provides a simplified representation of molecular structures but does not explicitly depict electrons at all.