Don't forget to take a ruler and calculator into the exam. Maths questions often start with the command word 'calculate'. You need to use numbers given in the question to work out the answer. When an ...

This video is an interactive lesson in calculating an atom’s mass and atomic number. Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells. The numbers of ...

Note: This video is designed to help the teacher better understand the lesson and is NOT intended to be shown to students. It includes observations and conclusions that students are meant to make on ...