Final answer:
The electron configuration of a sodium ion (Na+) is 1s² 2s² 2p⁶, which is identical to the noble gas neon's configuration and abbreviated as [Ne].
Step-by-step explanation:
The electron configuration of a sodium ion (Na+) is 1s² 2s² 2p⁶. This configuration corresponds to the complete filling of the first and second energy levels, equivalent to the noble gas neon (Ne). When sodium loses one electron to become Na+, it loses this electron from its outermost shell (the 3s subshell), resulting in a filled second energy level with an electron configuration identical to neon, which has atomic number 10. The shorthand notation for the electron configuration of Na+ is [Ne], representing the core electrons. Sodium's noble gas configuration for Na+ would be the neon core configuration without the additional 3s¹ electron.