The atom with a tiny heart

Science · Matter & Materials · ages 15-16

Name ______________________ Date ____________

Where do protons and neutrons live in the nuclear model?
- Spread through the whole atom
- Orbiting far outside the atom
- In a tiny central nucleus
What happened in the gold foil experiment?
- Most passed through, a few bounced back
- Every particle bounced back
- Every particle stopped in the foil
What does the atomic number count?
- Protons
- Neutrons only
- Protons plus neutrons
An atom has atomic number 6 and mass number 14. How many neutrons does it have?
- 6
- 8
- 20
Why did the bounce rule out the pudding model?
- The pudding had no electrons
- Spread out charge could only nudge, never fling back
- Gold foil is too thin
Why is nearly all the mass of an atom in the nucleus?
- Electrons are far lighter than protons and neutrons
- The nucleus spins fast
- Electrons fall out easily
A student says the nucleus holds almost all the volume of the atom.
Circle one: True False
A new experiment clearly breaks the current model of the atom. What should scientists do?
- Hide the results
- Keep the model and drop the results
- Replace or fix the model

Answer key

For grown-ups. Fold this page away before handing over the rest.

In a tiny central nucleus · All the positive charge and almost all mass sit at the centre.
Most passed through, a few bounced back · Most sailed through the empty atom, and rare near hits bounced.
Protons · The proton count fixes which element you have.
8 · Subtract protons from the total: 14 minus 6.
Spread out charge could only nudge, never fling back · Only a concentrated charge can throw a fast particle backward.
Electrons are far lighter than protons and neutrons · Electrons carry charge but almost no mass.
False · The nucleus holds the mass, while the space around holds the volume.
Replace or fix the model · A model survives only while it fits the evidence.