Have you ever wondered what our world is made from? Scientists have been asking this question for as long as there have been people and they have found a number of interesting answers. Some of these answers were accepted as the truth for a long time only to be discarded again. Others didn't survive as individual ideas but were expanded and added to. Today there is also a generally accepted idea of how our world is built. This idea is called the Standard Model.

The Standard Model assumes that everything in this world is made up of particles. These particles are extremely tiny. They are much smaller than anything you can see with your eyes or even with the best microscope ever built. There are many different kinds of particles. The smallest ones which are supposedly not built up of even smaller particles are called fundamental particles. Quarks , leptons and a few bosons are fundamental particles.

But what are particles? Since they are so small that we can't see them and we can't know what they look like, we can think of particles as being little "balls" or "points". On this website you will see the particles illustrated as different looking circles like the ones in the image to the left.

We can tell the different kinds of particles appart by their specific properties. For example, each kind of particle has a typical mass. Of course scientists can't just put the particles on a scale to see how heavy they are, but they've got their ways to find out what mass a particle has and once they know that, it is easier for them to guess what kind of particle they've got.

Another property which specifies a particle is its charges. One charge they can have is the electric charge; a particle can either have a positive or a negative electric charge. Additionally, there are electrically neutral particles which don't care how the other particles are charged, in contrary to the elctrically charged particles. Check out the particles on the right. If you drag two of them into the ring, you can see how they react to each other.

If I tell you that the electron (e) has an electric charge of -1 can you find out what charges the other particles have?

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