A monoatomic cation carrying a net charge of $+2$ contains exactly 24 electrons and 30 neutrons. The

Question

A monoatomic cation carrying a net charge of $+2$ contains exactly 24 electrons and 30 neutrons. The correct nuclear symbol identifying this specific ion is

Professor PC Thomas Classes · Answer

(a) : The ion is a cation with a $+2$ charge, meaning it has lost 2 electrons. If it currently possesses 24 electrons, the neutral atom must have had $24 + 2 = 26$ electrons. Therefore, the atomic number (number of protons) is $Z = 26$, which corresponds to Iron ($\mathrm{Fe}$). The mass number is the sum of protons and neutrons: $A = 26 + 30 = 56$. Hence, the correct symbol for the ion is ${}^{56}_{26}\mathrm{Fe}^{2+}$.