Particles and a Nucleus

In the picture

1. 1A lone electron: a tiny negative particle moving by itself.
2. 2A proton: a heavier positive particle.
3. 3A neutron: a heavier particle with no electric charge.
4. 4A compact nucleus: protons and neutrons joined in a tight core.

Examples

• Droplets on a cold window can merge into one larger drop.
• A magnet can pull loose paper clips into a tight cluster while other clips stay apart.

Quiz: Particles and a Nucleus (Age 12)

1. 1

   What can protons and neutrons do in this early hot, dense state?

   • Disappear and leave only empty space
   • Turn into electrons and move separately
   • Join together to form atomic nuclei
2. 2

   How are electrons described compared with protons and neutrons?

   • They are heavier and always inside the nucleus
   • They have no electric charge and join the nucleus
   • They are much lighter and can stay separate from nuclei
3. 3

   What makes up a compact nucleus?

   • Only lone electrons moving by themselves
   • Electrons joined with neutrons but no protons
   • Protons and neutrons joined in a tight core

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.