Final answer:
A Sodium ion (Na+) is isoelectronic with the noble gas Neon (Ne) as they both have the same number of electrons, which is 10. Neon is the nearest noble gas to sodium on the periodic table and shares the same electron count after sodium ionizes to Na+.
Step-by-step explanation:
A Sodium ion (Na+) is isoelectronic with neon (Ne), which means they both have the same number of electrons. The reason for this is that a sodium atom has 11 electrons, but when it loses one electron to become Na+, it is left with 10 electrons, the same as a neon atom, which also has 10 electrons. Neon is the nearest noble gas to sodium on the periodic table with an identical electron count.
The noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). These elements are characterized by their lack of reactivity and are often used in conditions where a non-reactive atmosphere is required. In the context of electronic configurations, noble gases provide reference points for the shorthand notation known as noble gas configuration.
The answer to the question is therefore Neon (Ne) since it directly precedes sodium in the periodic table and shares an isoelectronic configuration with the Na+ ion.