Protons, neutrons & electrons in atoms & ions (AQA GCSE Chemistry & Combined Science)

This lesson explains how to calculate the number of protons, neutrons and electrons in atoms and ions when given the atomic and mass numbers. The PowerPoint and accompanying resources are part of the second lesson in a series of 3 lessons which have been designed to cover the content of specification points 1.1.4, 1.1.5 & 1.1.6 of the AQA GCSE Chemistry and Combined Science specifications.

The lesson begins by challenging the students to put the chemical symbols for astatine, oxygen, iodine and carbon together to form the word atomic. Time is taken to explain the meaning of the atomic number and to emphasise how the number of protons in the nucleus is unique to atoms of that element. The students will learn that as the number of electrons is always the same as the number of protons in an atom, the atomic number can be used to calculate the numbers of both of these particles. Moving forwards, the mass number is considered and having been given the number of neutrons in a lithium atom, the students are challenged to articulate how the mass number and atomic number were used in this calculation. A series of worked examples are done as a class before the students are given the opportunity to challenge their understanding
The remainder of the lesson focuses on ions and how the number of protons, neutrons and electrons are calculated in these substances. Initially, the students are challenged to use their knowledge of the charge of an atom to deduce that ions must have differing numbers of protons and electrons. The standard annotation for ions are introduced and explained and a series of exam questions are then used to check understanding. Mark schemes for each of these final questions is embedded into the PowerPoint and the worksheet has been differentiated two ways