A particle is not made of anything smaller. What do we call it?
You have the two names: fundamental and composite. Now put them to work. Every particle you have met so far can be sorted with one question: is it made of anything smaller?
The proton is made of smaller particles. So the proton is composite.
The neutron is also made of smaller particles. So the neutron is also composite.
But the electron is not made of anything smaller. So the electron is fundamental.
A helium atom is made of smaller particles. So a helium atom is composite.
Every whole atom works the same way: it is made of smaller particles, so every atom is composite.
One question decides every case: is the particle made of anything smaller? If it is, the particle is composite. If it is not, the particle is fundamental.
Is an oxygen atom fundamental or composite?
An oxygen atom is made of protons, neutrons, and electrons.
A particle made of smaller particles is composite.
The oxygen atom is composite.
Quick-fire drill
Here are six quick sorts. Ask the one question each time: is it made of anything smaller?
A hydrogen atom: is it fundamental or composite?
The electron: is it fundamental or composite?
The neutron: is it fundamental or composite?
A gold atom: is it fundamental or composite?
The proton: is it fundamental or composite?
The electron knocked out of a sodium atom: is it fundamental or composite?
Your turn
Which of the following particles is fundamental?
A copper atom is classified as composite. Which feature decides the classification?
A student claims every electrically charged particle is composite. Which particle shows the claim is wrong?