Question

a neutral atom of \\(\ce{^{205}_{81}tl}\\) has
\\(\circ\\) 81 protons, 124 neutrons, and 81 electrons
\\(\circ\\) 81 protons, 205 neutrons, and 81 electrons
\\(\circ\\) 81 protons, 81 neutrons, and 81 electrons
\\(\circ\\) 81 protons, 124 neutrons, and 124 electrons

Explanation:

Step1: Determine number of protons

The atomic number (subscript) is 81, so protons = 81.

Step2: Calculate number of neutrons

Mass number (superscript) is 205. Neutrons = mass number - atomic number = \(205 - 81 = 124\).

Step3: Determine number of electrons

In a neutral atom, electrons = protons = 81.

Answer:

81 protons, 124 neutrons, and 81 electrons (the first option)