Introduction to Protons, Neutrons and Electrons

As discussed previously, there are many different kinds of subatomic particles (particles which are smaller than an atom). However, in this course we will only study three kinds: protons, neutrons and electrons. These three types of particle are very important in chemistry because they are the particles that atoms are made of.

Protons are positive, electrons are negative, neutrons are neutral

One of the differences between protons, neutrons and electrons is their charges. Protons are positively charged, electrons are negatively charged and neutrons are neutral. It is easy to remember that neutrons are neutral because the word neutron is very similar to the word neutral. Also, proton and positive both start with the letter p, which helps you to remember that protons are positive. Then you just have to remember that electrons are negative.

Electrons are smaller than protons and neutrons

These subatomic particles also differ in their sizes. Protons and neutrons are about the same size, but electrons are much smaller.

Diagrams of protons, neutrons and electrons

In the diagrams in this course, protons, neutrons and electrons will be represented by circles. A proton will be represented by a circle with a plus sign in it, to show that it is positively charged. A neutron will have the letter n in it to show that it is neutral. Finally, an electron will have a minus sign in it to show that it is negatively charged. Also, the electron will be drawn smaller than the other two particles. Note that the size difference between electrons and the other two particles is actually much greater than what is shown in these diagrams.

Diagram of a proton, neutron and electron. The proton is a red circle with a plus sign on it. The neutron is a grey circle with the letter 'n' on it. The electron is a smaller, blue circle with a minus sign on it.

A proton, a neutron and an electron - the three types of subatomic particle that make up atoms, ions and molecules.


Flashcards help you memorise information quickly. Copy each question onto its own flashcard and then write the answer on the other side. Testing yourself on these regularly will enable you to learn much more quickly than just reading and making notes.


Which three subatomic particles are atoms made of?


What type of charge does each of these particles have (positive, negative or neutral)?


How do the sizes of these particles compare with each other?


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