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

Atomic Structure

108 practice questions

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Practice questions

21–30 of 48 · Normal

  1. Question 21

    3 marks · Normal

    Chlorine exists mainly as two isotopes, and . The Periodic Table gives chlorine a relative atomic mass of 35.5.

    Explain why this value is not a whole number. Your answer should refer to isotopes and how the value is calculated.

    Answer and see the solution →

  2. Question 22

    4 marks · Normal

    The table shows the abundances of three isotopes of element X.

    IsotopeRelative Mass% Abundance
    X-101020
    X-111150
    X-121230
    Answer and see the solution →

  3. Question 23

    1 mark · Normal

    Which statement correctly describes all isotopes of an element?

    1. A.They have the same mass number but different atomic numbers.
    2. B.They have the same number of protons but different numbers of neutrons.
    3. C.They have different chemical properties.
    4. D.They contain the same number of neutrons.
    Answer and check →

  4. Question 24

    2 marks · Normal

    An atom of sodium-23 () has how many neutrons?

    Answer and see the solution →

  5. Question 25

    4 marks · Normal

    Consider two isotopes of carbon: and .

    (a)

    State the number of protons and neutrons in .

    [1 mark]
    (b)

    State the number of protons and neutrons in .

    [1 mark]
    (c)

    Explain why and are considered isotopes of the same element.

    [1 mark]
    (d)

    Describe one way in which the two isotopes differ.

    [1 mark]
    Answer and see the solution →

  6. Question 26

    2 marks · Normal

    State the number of electrons in:

    (a)

    an atom of magnesium (atomic number = 12)

    [1 mark]
    (b)

    an atom of phosphorus (atomic number = 15)

    [1 mark]
    Answer and see the solution →

  7. Question 27

    4 marks · Normal

    The following information is given about three atoms:

    Data about three atoms
    AtomAtomic number
    A6
    B18
    C2
    (a)

    State the number of electrons in atom A.

    [1 mark]
    (b)

    State the number of electrons in atom B.

    [1 mark]
    (c)

    State the number of electrons in atom C.

    [1 mark]
    (d)

    Explain why the number of protons is equal to the number of electrons in a neutral atom.

    [1 mark]
    Answer and see the solution →

  8. Question 28

    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 →

  9. Question 29

    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 →

  10. Question 30

    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 →