Final answer:
The correct ion formation equation for sodium (Na) is (Na → Na⁺ + e⁻), where sodium loses its single valence electron to form a positively charged cation, Na⁺, with an electron configuration similar to neon.
Step-by-step explanation:
The ion formation equation for sodium (Na) is: Na → Na⁺ + e⁻. Sodium has one valence electron in its outermost shell, which it loses to form a sodium cation (Na⁺). Following the loss of this single valence electron, the sodium ion acquires a positive charge and an electron configuration that is identical to that of neon, a noble gas with a stable octet.
The process of losing an electron to form a cation requires energy, known as the ionization energy. The ionization energy for sodium is the energy needed to remove its one valence electron. Therefore, the correct equation representing sodium's ion formation, with its ionization energy, is option A: ( Na → Na⁺ + e⁻ ).