Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Atomic Structure
108 practice questions
Topics covered
Practice questions
1–10 of 16 · Hard
Question 1
2 marks · Hard
Answer and see the solution →State the meaning of the following terms:
(a)[1 mark]atom
(b)[1 mark]molecule
Question 2
5 marks · Hard
Answer and see the solution →Ammonia has the chemical formula NH₃.
(a)[1 mark]State what an atom is.
(b)[1 mark]Describe what is meant by a molecule.
(c)[1 mark]How many atoms are present in one molecule of ammonia?
(d)[1 mark]Write the names of the elements that form a molecule of ammonia.
(e)[1 mark]Explain, using ammonia as an example, how a molecule is different from an atom.
Question 3
2 marks · Hard
Answer and see the solution →Give one similarity and one difference between atoms and molecules.
(a)[1 mark]State one way in which atoms and molecules are similar.
(b)[1 mark]State one way in which atoms and molecules are different.
Question 4
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 5
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 6
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.
Question 7
2 marks · Hard
Answer and see the solution →A sample of element Q contains 10% of isotope Q-40 and 90% of isotope Q-42.
Calculate the relative atomic mass of Q. Give your answer to one decimal place.
Question 8
5 marks · Hard
Answer and see the solution →(a)[1 mark]Describe what isotopes are.
(b)[3 marks]The element magnesium has isotopes with mass numbers 24, 25, and 26. Give the number of protons and neutrons in each of these isotopes.
Isotope Number of protons Number of neutrons ^24Mg ^25Mg ^26Mg (c)[1 mark]Explain why magnesium-24, magnesium-25, and magnesium-26 all have the same chemical properties.
Question 9
2 marks · Hard
Answer and see the solution →The element X has two stable isotopes: X-64 (mass = 64, abundance = 73%) and X-66 (mass = 66, abundance = 27%).
Calculate the relative atomic mass of X. Give your answer to one decimal place.
Question 10
2 marks · Hard
Answer and see the solution →Sulfur has an atomic number of 16.
Calculate the number of electrons in two neutral atoms of sulfur.