Question

what do the blue circles represent in the atom?
valance electrons
core electrons
protons
neutrons
20p⁺
20n⁰

Explanation:

Protons and neutrons are located in the atom's nucleus (labeled 20p⁺ and 20n⁰ here). Valence electrons are the outermost electrons (the red circles in shell 4). The blue circles are electrons in the inner shells (1, 2, 3), which are defined as core electrons.

Answer:

Core electrons