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Question

Difficulty: MediumAtomic Structure and Periodic Table

An atom of potassium has a mass number of 3939 and contains 2020 neutrons in its nucleus. When this atom forms a stable potassium ion (K+K^+) by losing one electron, what is the total number of subatomic particles (protons, neutrons, and electrons) present in the ion?

  1. A
    3939
  2. 5757Answer
  3. C
    5858
  4. D
    7777

Answer

The potassium ion contains a total of 5757 subatomic particles.
The correct answer is 5757. The number of protons is found by subtracting the neutron count from the mass number (39−20=1939 - 20 = 19). Because the potassium ion carries a +1+1 charge (K+K^+), it has lost one electron, leaving 1818 electrons. Adding all subatomic constituents gives 19 protons+20 neutrons+18 electrons=57 total particles19\text{ protons} + 20\text{ neutrons} + 18\text{ electrons} = 57\text{ total particles}.

Step-by-Step Solution

1
Calculate the number of protons in the potassium atom.
Protons = 39−20=1939 - 20 = 19
The mass number (AA) is the sum of protons (ZZ) and neutrons (NN), so Z=A−NZ = A - N.
2
Determine the number of electrons in the K+K^+ ion.
Electrons = 19−1=1819 - 1 = 18
A neutral potassium atom has 1919 electrons; forming a +1+1 cation requires losing 11 electron.
3
Sum the total number of protons, neutrons, and electrons.
Total particles = 19+20+18=5719 + 20 + 18 = 57
The question requests the combined count of all subatomic particles in the ion.

Key Concept

Subatomic particle calculations in atomic structure and ions
Estimated Time:1m 0s
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Topics

Atomic Structure and Periodic Table

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