Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Atomic number and mass number
19 practice questions
Practice questions
1–3 of 3 · Hard
Question 1
2 marks · Hard
Answer and see the solution →Helium-3 is an isotope of helium with a mass number of 3. It has 2 protons. State the number of neutrons and electrons in a neutral atom of helium-3.
Question 2
5 marks · Hard
Answer and see the solution →The element chlorine occurs naturally as two main isotopes: chlorine-35 and chlorine-37. The relative abundances of these isotopes are 75% chlorine-35 and 25% chlorine-37.
(a)[1 mark]Define the term 'isotope'.
(b)[1 mark]State the atomic number of chlorine.
(c)[1 mark]Explain, using your knowledge of atomic structure, why chlorine-35 and chlorine-37 are isotopes of the same element.
(d)[2 marks]Calculate the relative atomic mass of chlorine to 1 decimal place. Show your working.
Question 3
2 marks · Hard
Answer and see the solution →State the relative mass and relative charge of a neutron, and explain how these properties compare to those of a proton.