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Difficulty: Very hardAtomic Structure and Periodic Table

An atom of an unknown element forms a stable ion with a +3+3 charge. This specific ion contains 1010 electrons. If the mass number of a particular isotope of this element is equal to twice its atomic number plus one, how many neutrons does the nucleus of this isotope contain?

  1. A
    8
  2. B
    11
  3. 14Answer
  4. D
    27

Answer

The isotope contains 14 neutrons.
To solve this, first find the atomic number. A +3+3 ion has lost 3 electrons. Since this ion has 10 electrons, the neutral atom must have 10+3=1310 + 3 = 13 protons (atomic number 13). Next, calculate the mass number using the provided formula: 2(13)+1=272(13) + 1 = 27. Finally, subtract the number of protons from the mass number to find the number of neutrons: 27−13=1427 - 13 = 14.

Step-by-Step Solution

1
Determine the atomic number (number of protons).
The atomic number is 13.
A +3+3 charge indicates the neutral atom lost 3 negatively charged electrons. Since the ion has 10 electrons, the neutral atom originally had 10+3=1310 + 3 = 13 electrons. The number of protons equals the number of electrons in a neutral atom.
2
Calculate the mass number.
The mass number is 27.
The problem states the mass number is twice the atomic number plus one: 2(13)+1=272(13) + 1 = 27.
3
Calculate the number of neutrons.
There are 14 neutrons.
The number of neutrons is found by subtracting the atomic number (protons) from the mass number: 27−13=1427 - 13 = 14.

Key Concept

Calculating subatomic particles for ions by first determining the true atomic number from the ion's charge and electron count, then utilizing mass number relationships.
Estimated Time:1m 30s
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Topics

Atomic Structure and Periodic Table

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