The symbol equation for the formation of a sodium ion from an atom is:

Na → Na⁺ + e⁻

Here's what the equation represents:

* Na: Represents a neutral sodium atom.

* Na⁺: Represents a sodium ion with a +1 charge.

* e⁻: Represents an electron that is lost by the sodium atom.

Explanation:

Sodium (Na) has one valence electron in its outermost shell. To achieve a stable electron configuration, it loses this electron and forms a positively charged ion, Na⁺. The lost electron is represented by e⁻.