Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Counting the number of electrons in an atom
21 practice questions
Practice questions
1–10 of 21
Question 1
1 mark · Easy
Answer and check →State the number of electrons in a neutral atom of lithium, which has an atomic number of 3.
Question 2
3 marks · Easy
Answer and see the solution →(a)[1 mark]State what is meant by the atomic number of an atom.
(b)[2 marks]Draw a table to show the number of electrons in each of the following neutral atoms:
Element Atomic number Beryllium 4 Fluorine 9 Question 3
2 marks · Easy
Answer and see the solution →Calcium has an atomic number of 20. Calculate the number of electrons in a neutral atom of calcium. Show your working.
Question 4
2 marks · Easy
Answer and see the solution →Explain why a neutral atom of aluminium (atomic number 13) also contains 13 electrons.
Question 5
3 marks · Easy
Answer and see the solution →The table below shows the atomic numbers for four elements.
Element Atomic number Phosphorus 15 Sodium 11 Nitrogen 7 Argon 18 (a)[2 marks]For each element, state the number of electrons in its neutral atom.
(b)[1 mark]Explain briefly how you worked out your answers.
Question 6
1 mark · Easy
Answer and check →What is the number of electrons in a neutral atom of silicon, which has atomic number 14?
Question 7
3 marks · Easy
Answer and see the solution →(a)[1 mark]Complete the following sentence: An atom is neutral because...
(b)[1 mark]Potassium has atomic number 19. State the number of electrons in a neutral atom of potassium.
(c)[1 mark]Explain your answer to part (b).
Question 8
2 marks · Easy
Answer and see the solution →Show how you would calculate the number of electrons in a neutral atom of argon, given its atomic number is 18.
Question 9
2 marks · Normal
Answer and see the solution →State the number of electrons in:
(a)[1 mark]an atom of magnesium (atomic number = 12)
(b)[1 mark]an atom of phosphorus (atomic number = 15)
Question 10
4 marks · Normal
Answer and see the solution →The following information is given about three atoms:
Data about three atoms Atom Atomic number A 6 B 18 C 2 (a)[1 mark]State the number of electrons in atom A.
(b)[1 mark]State the number of electrons in atom B.
(c)[1 mark]State the number of electrons in atom C.
(d)[1 mark]Explain why the number of protons is equal to the number of electrons in a neutral atom.