The numbers of electrons, protons, and neutrons in a species are equal to `18,16`, and `16`, respectively. Write the symol for the species in the standard format.
Strategy: Before usding the standard notation `_(Z)^(A)X`, find out wheter the species is a neutral atom, a cation, or an anion. if it is a neutral atom, Eq is valid, i.e.
Number of protons = Number of electrons = Atomic number
If the species is an ion, determine whether the number of protons is larger (cation, a positive ion) or smaller (anion, a negative ion) than the number of electrons. Number of neurtons is always given by Eq. i.e., `N=A-Z`, whether the species is neutral or charged.

Explanation

Number of protons `=` Atomic number `= 16`
The element, according to the periodic table, is sulphur `(S)`.
Number of protons `+` Number of neutrons `=` Mass number `= 16 + 16 = 32`
As the number of protons is not equal to the number of electrons, the species is not neutral, but is negatively charged (anion) due to two extra electorns. Thus, the symbol is `._(16)^(32)S^(2-)`