Final answer:
A Lewis electron-dot diagram for calcium oxide depicts Ca²⁺ with no valence electrons and O²⁻ with a full shell of eight valence electrons, representing stable ionic formation.
Step-by-step explanation:
The Lewis electron-dot diagram that represents calcium oxide involves calcium (Ca) losing two electrons to form the Ca²⁺ cation, and oxygen (O) gaining those electrons to form the O²⁻ anion. The diagram for the calcium cation is simply Ca²⁺, with no dots representing valence electrons since calcium has lost its two valence electrons. The diagram for the oxide anion is :O⁻⁻: with a total of eight dots representing its full valence shell of electrons. Together, the calcium ion and oxide ion combine to form calcium oxide (CaO), a stable ionic compound due to each ion having full valence shells.