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Isotope counter: what changes an element’s name

Ten identical tokens with three raised codes turn atomic notation into an arrangement you can check. Make your own complete kit, interpret three neutral atoms and test what determines the element’s name.

Age
12–14 years
Length
approx. 45 min
Level
Easy
Where you teach
School
Purpose
Educational
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How to run this session

Stages and timing
  1. Ten solid bodies
  2. Three relief codes

What gets built

Pupils determine proton, neutron and electron counts from Z and A and recognise isotopes of the same element.

What it practises
  • Determining p/n/e from Z and A
  • Recognising isotopes
  • Reading and writing nuclide notation

Success criteria
  • I have 10 solid Ø20 mm tokens: 3 with one stroke, 4 with two strokes and 3 with a circle; every relief mark is attached to its body.
  • For each of the three neutral atoms, I independently record p=Z, n=A−Z, e=Z and the symbol with A at the upper left and Z at the lower left. Only then do I compare answers.
  • Before each task I clear the active fields and put unused tokens in Reserve. I compare H-1/H-2, H-2/He-4 and H-1/He-3; for He-3 I use the supplied Z=2,A=3 record without another build.
  • I justify an isotope pair using equal Z/protons and different A/neutrons. A counts protons and neutrons; it is not tabulated atomic mass, and I do not round atomic mass to obtain A.

What you need
Filament
PLA
Colours
colour shown in the illustration
Also
3D pen, Transparent work mat, A4 printouts and an answer sheet, Pencil, Ruler

Files

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Version 3c36c4cc-a885-4d4e-8116-0734bc052156 Updated 2026-10-19

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