Final answer:
Calcium oxide (CaO) has Ca2+ and O2- ions with electron structures identical to the inert gases argon (Ar) and neon (Ne), respectively, due to the transfer of electrons and ionic bonding.
Step-by-step explanation:
Calcium oxide (CaO) exhibits predominantly ionic bonding. The Ca2+ ion, after losing two electrons, has an electron structure identical to the inert gas argon (Ar), whose atomic number is 18. Similarly, the O2− ion, by gaining two electrons, attains an electron structure identical to the inert gas neon (Ne), with atomic number 10. These electron configurations correspond to the noble or inert gases, which are known for their chemical stability.
The formation of these ions is through the transfer of electrons, where calcium donates two electrons to achieve the electron configuration of argon, and oxygen accepts two electrons to achieve that of neon. The ionic bond in CaO results from the electrostatic attraction between the oppositely charged ions, forming a stable compound.