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Difficulty: HardAtomic Structure and Periodic Table

An isotope of a neutral atom has a mass number of 3131 and contains 1616 neutrons in its nucleus. If this atom gains 33 electrons to form a stable anion, what is the total number of subatomic particles (protons, neutrons, and electrons) in the resulting ion?

  1. A
    4343
  2. B
    4646
  3. 4949Answer
  4. D
    6464

Answer

The total number of subatomic particles in the resulting ion is 4949.
The atomic number is found by subtracting neutrons from the mass number (31−16=1531 - 16 = 15 protons). A neutral atom has 1515 electrons, and gaining 33 electrons increases the electron count to 1818. Adding 1515 protons, 1616 neutrons, and 1818 electrons gives a total of 4949 subatomic particles.

Step-by-Step Solution

1
Determine the number of protons in the atom.
1515 protons
The atomic number equals the mass number minus the number of neutrons: 31−16=1531 - 16 = 15.
2
Determine the number of electrons in the resulting anion.
1818 electrons
A neutral atom has equal numbers of protons and electrons (1515). Gaining 33 electrons yields 15+3=1815 + 3 = 18 electrons.
3
Sum all subatomic particles (protons, neutrons, and electrons) in the ion.
15+16+18=4915 + 16 + 18 = 49
The total particle count is the sum of 1515 protons, 1616 neutrons, and 1818 electrons.

Key Concept

Calculating subatomic particle totals in ions using mass number and charge
Estimated Time:1m 30s
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Topics

Atomic Structure and Periodic Table

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