Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Principles of Chemistry
991 practice questions
Topics covered
- States of Matter102 practice questions
- Elements, Compounds and Mixtures69 practice questions
- Atomic Structure108 practice questions
- The Periodic Table103 practice questions
- Chemical Formulae, Equations and Calculations Part 119 practice questions
- Chemical Formulae, Equations and Calculations Part 2144 practice questions
- Ionic Bonding143 practice questions
- Covalent Bonding68 practice questions
- Metallic Bonding19 practice questions
- Electrolysis198 practice questions
Practice questions
41–50 of 161 · Hard
Question 41
5 marks · Hard
Answer and see the solution →Molybdenum (Mo) is an element with an atomic number of 42. One isotope of molybdenum has a mass number of 98.
(a)[1 mark]State the number of protons in an atom of this isotope.
(b)[2 marks]Calculate the number of neutrons in this isotope.
(c)[2 marks]Explain how you would determine the number of electrons in a neutral atom of molybdenum.
Question 42
2 marks · Hard
Answer and see the solution →The symbol for antimony is Sb. An atom of antimony has 51 protons and a mass number of 123. State the number of electrons and calculate the number of neutrons in a neutral atom of antimony.
Question 43
9 marks · Hard
Answer and see the solution →The Periodic Table symbol for the element bromine (B r) is shown below.
Symbol Mass number Name Atomic number Br 80 Bromine 35 Bromine has two main isotopes: B r-79 and B r-81.
(a)[2 marks]State the meaning of atomic number and mass number.
(b)For a neutral atom of bromine-80, calculate the number of:
(i)[1 mark]protons
(ii)[2 marks]neutrons
(iii)[1 mark]electrons
(c)[3 marks]Describe the relative mass and charge of each sub-atomic particle found in a bromine atom.
Question 44
2 marks · Hard
Answer and see the solution →Element Z is found in Group 5 and Period 3 of the Periodic Table.
Explain what the group and period numbers tell you about the arrangement of electrons in an atom of element Z.
Question 45
5 marks · Hard
Answer and see the solution →Element Y has an atomic number of 17.
(a)[2 marks]Write the full electronic configuration of element Y.
(b)[1 mark]How many electron shells does an atom of element Y have?
(c)[2 marks]In which group of the Periodic Table is element Y found? Explain your answer.
Question 46
2 marks · Hard
Answer and see the solution →Explain why the atomic number of an element determines its position in the Periodic Table and not its mass number.
Question 47
2 marks · Hard
Answer and see the solution →The diagram below represents the electronic configuration of an atom using shells and electrons:
Electronic configuration of an atom X Shell 1 contains 2 electrons, shown as crosses or dots. Shell 2 contains 4 electrons, shown as crosses or dots.
Interpret this diagram to answer the following:
(a)[1 mark]How many electrons are present in atom X?
(b)[1 mark]State the electronic configuration of atom X using numbers to show the electrons in each shell.
Question 48
5 marks · Hard
Answer and see the solution →Answer the following about the rules for filling electron shells up to the third shell.
(a)State the maximum number of electrons that can occupy:
(i)[1 mark]the first shell
(ii)[1 mark]the second shell
(iii)[1 mark]the third shell, up to atomic number 10
(b)[1 mark]Describe the order in which electrons fill these shells in an atom.
(c)[1 mark]Explain why the first shell is always filled before electrons occupy the second shell.
Question 49
2 marks · Hard
Answer and see the solution →Draw a diagram to show the electronic configuration of an atom of fluorine (atomic number 9). Represent the shells as circles and the electrons as dots or crosses.
Question 50
2 marks · Hard
Answer and see the solution →An unknown element X has the electronic configuration 2, 8, 3. State the group and period of element X in the Periodic Table.