2 Atoms, ions, and compounds
OCR Chemistry A Exam-style questions
1 This question is about atomic structure.
a Complete Table 1.
Table 1 Charges and masses of some subatomic particles, relative to the proton
Proton Neutron
Relative mass
Relative charge
(2 marks)
b An atom of element X contains four times as many protons as are found in
an atom of 12C. An atom of element X contains 29 neutrons.
i State the number of protons found in one atom of 12C.
(1 mark)
ii Deduce the symbol, including mass number and atomic number, for this
atom of element X.
(2 marks)
c The particles in each pair below differ only in the number of protons or
neutrons or electrons. State what the difference is within each pair:
i 1H and 2H
(2 marks)
31
ii P3− and 32S2−
(2 marks)
, 2 Atoms, ions, and compounds
OCR Chemistry A Exam-style questions
2 Sir Humphry Davy was the first to isolate potassium and magnesium in the early
1800s.
a Potassium only has two stable isotopes. These are K-39 and K-41.
i Explain, in terms of subatomic particles, the meaning of the term
isotopes.
(2 marks)
ii The two isotopes of potassium have the same chemical properties.
Explain why.
(1 mark)
iii Use information from the Periodic Table to deduce which isotope of
potassium is more abundant. Explain how you reached your answer.
(1 mark)
b The Chelyabinsk meteorite hit Russia in February 2013. Meteorites often
contain magnesium. The magnesium in a meteorite was analysed and was
found to consist of three isotopes. Information about these isotopes is given
in Table 2.
Table 2 Relative isotopic mass and abundance of magnesium isotopes in a meteorite
Isotope Relative isotopic mass Abundance (%)
Magnesium-24 24.00 74.65
Magnesium-25 25.00 10.00
Magnesium-26 26.00 15.35
i Calculate the relative atomic mass of this sample of magnesium. Give
your answer to two decimal places.
Relative atomic mass (2 marks)
OCR Chemistry A Exam-style questions
1 This question is about atomic structure.
a Complete Table 1.
Table 1 Charges and masses of some subatomic particles, relative to the proton
Proton Neutron
Relative mass
Relative charge
(2 marks)
b An atom of element X contains four times as many protons as are found in
an atom of 12C. An atom of element X contains 29 neutrons.
i State the number of protons found in one atom of 12C.
(1 mark)
ii Deduce the symbol, including mass number and atomic number, for this
atom of element X.
(2 marks)
c The particles in each pair below differ only in the number of protons or
neutrons or electrons. State what the difference is within each pair:
i 1H and 2H
(2 marks)
31
ii P3− and 32S2−
(2 marks)
, 2 Atoms, ions, and compounds
OCR Chemistry A Exam-style questions
2 Sir Humphry Davy was the first to isolate potassium and magnesium in the early
1800s.
a Potassium only has two stable isotopes. These are K-39 and K-41.
i Explain, in terms of subatomic particles, the meaning of the term
isotopes.
(2 marks)
ii The two isotopes of potassium have the same chemical properties.
Explain why.
(1 mark)
iii Use information from the Periodic Table to deduce which isotope of
potassium is more abundant. Explain how you reached your answer.
(1 mark)
b The Chelyabinsk meteorite hit Russia in February 2013. Meteorites often
contain magnesium. The magnesium in a meteorite was analysed and was
found to consist of three isotopes. Information about these isotopes is given
in Table 2.
Table 2 Relative isotopic mass and abundance of magnesium isotopes in a meteorite
Isotope Relative isotopic mass Abundance (%)
Magnesium-24 24.00 74.65
Magnesium-25 25.00 10.00
Magnesium-26 26.00 15.35
i Calculate the relative atomic mass of this sample of magnesium. Give
your answer to two decimal places.
Relative atomic mass (2 marks)
