CAIE A Level Chemistry 9701 · Atomic structure
Three beams of particles – protons, electrons and neutrons – are all moving at the same velocity. Each beam is directed separately into a uniform electric field. The protons are deflected slightly towards the negative plate, the electrons are deflected strongly towards the positive plate, and the neutrons are not deflected at all. Explain these observations in terms of the relative charges and masses of the three subatomic particles.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.