The total number of isoelectronic species from the given set is _____.
O$$^{2-}$$, F$$^-$$, Al, Mg$$^{2+}$$, Na$$^+$$, O$$^+$$, Mg, Al$$^{3+}$$, F

Isoelectronic species have the same number of electrons.

Counting electrons for each species:

• O²⁻: 8 + 2 = 10 electrons
• F⁻: 9 + 1 = 10 electrons
• Al: 13 electrons
• Mg²⁺: 12 - 2 = 10 electrons
• Na⁺: 11 - 1 = 10 electrons
• O⁺: 8 - 1 = 7 electrons
• Mg: 12 electrons
• Al³⁺: 13 - 3 = 10 electrons
• F: 9 electrons

Species with 10 electrons: O²⁻, F⁻, Mg²⁺, Na⁺, Al³⁺ → 5 isoelectronic species

The total number of isoelectronic species is $$\mathbf{5}$$.