Final answer:
The ion that has the electron configuration of a noble gas is the sodium ion.
Step-by-step explanation:
The ion that has the electron configuration of a noble gas is the sodium ion.
The electron configuration of sodium is 1s²2s²2p63s¹. The first ten electrons of the sodium atom are the inner-shell electrons, which have the same configuration as the element neon (Z = 10). Therefore, we can use the noble gas configuration notation to represent the electron configuration of sodium as [Ne] 3s¹.
This means that sodium has the same electron configuration as the noble gas neon, which has a full outer shell and cannot incorporate any more electrons. Sodium achieves a noble gas configuration by losing its valence electron to form a positively charged sodium ion.