AQA A-Level Chemistry Paper 3, 2023: Question 7

1 mark · Easy difficulty · Multiple Choice

Number of Fundamental Particles in Mg This question involves identifying the correct number of protons, neutrons, and electrons in the Mg ion by interpreting atomic and ionic properties of magnesium.

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Question

AQA A-Level Chemistry Paper 3, 2023: Question 7
Question text

07 Which row shows the number of each fundamental particle in one 25Mg2+ ion?

[1 mark]

protons neutrons electrons

A 12 12 10

B 14 11 12

C 12 13 10

D 12 13 12

Mark scheme

Show the mark scheme Mark scheme for AQA A-Level Chemistry Paper 3, 2023: Question 7

Question Marking Guidance Mark Comments

07 C 1 (AO2) C 12 13 10

How to answer it

Step-by-Step Guide: Identifying Fundamental Particles in 25Mg2+

Step 1: Determine the Number of Protons

The atomic number of magnesium (Mg) is 12, meaning it has 12 protons .

Teacher Tip: The number of protons is always equal to the atomic number of the element, regardless of isotopes or charge.

Step 2: Determine the Number of Neutrons

The mass number of 25Mg is 25. The number of neutrons is calculated as:

  • Neutrons = Mass number - Atomic number
  • Neutrons = 25 - 12 = 13 neutrons
Teacher Tip: Subtract the number of protons (atomic number) from the mass number to find the neutrons.

Step 3: Determine the Number of Electrons

The 25Mg2+ ion has a 2+ charge, meaning it has lost 2 electrons compared to a neutral magnesium atom.

  • Neutral Mg has 12 electrons (equal to the number of protons).
  • 25Mg2+: Electrons = 12 - 2 = 10 electrons .
Teacher Tip: For positively charged ions, subtract the charge from the total number of electrons in the neutral atom.

Step 4: Verify the Correct Row

Based on the calculations:

  • Protons: 12
  • Neutrons: 13
  • Electrons: 10

The correct row is: C

Teacher Tip: Double-check all values to ensure they match the provided options.

Topics

Physical Chemistry · 3.1.1 Atomic Structure

Question and mark scheme from the AQA A-Level Chemistry examination, Paper 3, 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.