Simulation Description: Atomic number and Mass number
Mass Number & Atomic Number — Simulation
Two sliders let students adjust protons (1–18) and neutrons (0–22). The screen updates instantly showing the element symbol and name on a periodic-table-style tile, the live equation A = Z + N, and a colour-split bar showing the proton/neutron ratio in the nucleus.
Class Activity — “What’s My Element?” (10–15 min, KS4)
Teacher projects one clue at a time. Students use the sliders to find the answer.
| Clue | Answer |
|---|---|
| Z = 6, A = 12 | Carbon |
| Z = 8, A = 16 | Oxygen |
| Z = 11, A = 23 | Sodium |
| Z = 17, A = 35 | Chlorine |
| Z = 2, A = 4 | Helium |
| Z = 26, A = 56 | (slider maxes out — discuss why) |
Discussion prompt: “Chlorine-35 and Chlorine-37 both have Z = 17. Change only the neutrons slider. What changes? What stays the same?” — introduces isotopes naturally without needing a new lesson.