Final answer:
Each oxygen atom has six valence electrons. In a molecule like the carbonate ion, CO3^2-, after accounting for bonding, the remaining electrons are placed as lone pairs to complete the octets for the oxygen atoms.
Step-by-step explanation:
In the model you've made, each oxygen atom has six valence electrons. When constructing molecules like CO32-, for example, you would need to account for the electrons due to the charge in addition to those provided by the atoms. In this case, there would be a total of 24 valence electrons from the oxygen atoms (6 electrons each) plus 4 valence electrons from the carbon atom, with 2 additional electrons due to the molecule's 2- charge, adding up to 24 + 4 + 2 = 30 valence electrons. However, after forming bonds, the remaining electrons are distributed amongst the oxygen atoms as lone pairs, ensuring that all atoms achieve a full octet.