Question

The number of electrons, protons and neutrons in a species is equal to 10, 8 and 8 respectively. Assign the proper symbol to the species.

• A. ${}_{16}^{32}S$
• B. ${}_{16}^{32}{S}^{2-}$
• C. ${}_8^{16}{O}^{2-}$
• D. ${}_8^{10}{O}^{2-}$

Answer 1

The correct option is C ${}_8^{16}{O}^{2-}$

In a neutral atom, number of electrons = number of protons.
Since the number of protons is less than number of electrons, the species is an anion that has a -2 charge.
Atomic number = number of protons (number of protons is always constant) Atomic number = 8
Mass number = number of neutrons + number of protons
Mass number = 8 + 8 = 16
Symbol of species is: ${}_8^{16}{O}^{2-}$