Question

For the element Na, what is the greatest energy level and how many electrons are in this energy level?

Is it more beneficial to gain or lose electrons to obtain noble gas configuration?

What would be the charge on the ion?

Answer 1

The electronic configuration of Na is 1s² 2s² 2p⁶ 3s¹. This gives the orbital with the greatest energy as the 3s orbital. This orbital in Na possesses only one electron. The nearest noble gas' configuration is that of neon which is 1s² 2s² 2p⁶ and the other noble gas argon has a configuration of 1s² 2s² 2p⁶ 3s² 3p⁶. So it can be seen that Na has a half-filled s-orbital. To attain a noble gas configuration, the easiest way for Na is to lose one electron and become a monopositive cation Na⁺. Otherwise, it should gain 7 electrons and be Na^7-. Being a metal and having a low effective nuclear charge, this combined with the highly positive electron-gain enthalpy of Na prevents such an anion from forming as that many electrons can never be held together within the atom structure by Na's nucleus. So, it can be concluded that Na will attain the noble gas configuration of Ne by losing one electron and be Na⁺ with a charge of +1.