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Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section

Counting the number of electrons in an atom

21 practice questions

Start practising (21 questions)

Practice questions

11–20 of 21

  1. Question 11

    3 marks · Normal

    Potassium is a metal with an atomic number of 19.

    Calculate the number of electrons in a neutral atom of potassium. Show your working.

    Answer and see the solution →

  2. Question 12

    4 marks · Normal

    The table shows the atomic numbers of four elements.

    Atomic numbers of elements
    ElementAtomic number
    Fluorine9
    Neon10
    Sodium11
    Aluminium13
    (a)

    Which element in the table has 13 electrons in its atom? Give its name.

    [1 mark]
    (b)

    Which of these elements has 9 electrons in its atom? Give its name.

    [1 mark]
    (c)

    Explain why the number of electrons in a neutral atom is the same as its atomic number.

    [2 marks]
    Answer and see the solution →

  3. Question 13

    1 mark · Normal

    Which statement is correct for a neutral atom of sulfur (atomic number 16)?

    1. A.It has 8 electrons.
    2. B.It has 16 electrons.
    3. C.It has 32 electrons.
    4. D.It has 16 protons and 8 electrons.
    Answer and check →

  4. Question 14

    2 marks · Normal

    Give the number of electrons in each of the following neutral atoms:

    (a)

    Chlorine (atomic number = 17)

    [1 mark]
    (b)

    Argon (atomic number = 18)

    [1 mark]
    Answer and see the solution →

  5. Question 15

    4 marks · Normal

    The table below lists the names and atomic numbers of four different elements.

    Elements and their atomic numbers
    ElementAtomic number
    Carbon6
    Oxygen8
    Sodium11
    Chlorine17
    (a)

    Write down the number of electrons in a neutral atom of oxygen.

    [1 mark]
    (b)

    Write down the number of electrons in a neutral atom of sodium.

    [1 mark]
    (c)

    Write down the number of electrons in a neutral atom of chlorine.

    [1 mark]
    (d)

    Explain why the number of electrons is the same as the atomic number in a neutral atom.

    [1 mark]
    Answer and see the solution →

  6. Question 16

    2 marks · Normal

    State the number of electrons in a neutral atom of fluorine, which has an atomic number of 9. Give your answer with a reason.

    Answer and see the solution →

  7. Question 17

    4 marks · Normal

    A student is studying atoms of three elements: Element X, Element Y, and Element Z.

    Atomic numbers of three elements.
    ElementAtomic number
    X5
    Y12
    Z8
    (a)

    State the number of electrons in a neutral atom of element X.

    [1 mark]
    (b)

    Explain why the number of electrons in a neutral atom of element Y is 12.

    [2 marks]
    (c)

    Calculate the total number of electrons in 2 neutral atoms of element Z.

    [1 mark]
    Answer and see the solution →

  8. Question 18

    3 marks · Normal

    Calculate the number of electrons in a sample containing 5 neutral atoms of beryllium. Atomic number of beryllium = 4. Show your working.

    Answer and see the solution →

  9. Question 19

    2 marks · Hard

    Sulfur has an atomic number of 16.

    Calculate the number of electrons in two neutral atoms of sulfur.

    Answer and see the solution →

  10. Question 20

    5 marks · Hard

    The table below gives information about three elements.

    Atomic number of elements
    ElementAtomic number
    A7
    B12
    C15
    (a)

    State the number of electrons in a neutral atom of element B.

    [1 mark]
    (b)

    Element C is found in a rock sample containing 5 atoms. Calculate the total number of electrons in all these atoms.

    [2 marks]
    (c)

    Explain why a neutral atom of element A contains the same number of electrons as its atomic number.

    [2 marks]
    Answer and see the solution →