 |  | | | Picture 1. In 2002, there were 115 known element. However, those above 109 are highly unstable and have been made in only tiny quantities. |
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| | From atoms to The Standard Model | | | | | | For over 2 000 years, people have wondered about the fundamental building blocks of matter. As far back as 440 BC, the Greek Leucippus and his pupil Democritus coined the term atomos to describe the smallest particle of matter. It translates to mean something that is indivisible. In the eighteenth century, the chemist John Dalton, revived the term when he suggested that each element was made up of unique atoms and the atoms of an element are all the same. At the time, there were about 35 known elements. This simple model could explain the millions of different materials around us. Differences between the atoms give the elements their different chemical properties. | | | |
| Fundamental (or not) | | | | | | For a while then, it seemed that atoms were fundamental. As their name suggests, they could not be split into anything simpler. This meant that all of matter was made of about seventy fundamental particles (because there were new elements being discovered all the time). However, towards the end of the 19th century, it became clear that atoms are not fundamental ~ they themselves are made of smaller particles. One of these atomic particles is the electron, which we now think is fundamental. It is a member of the lepton family, one of the two families of fundamental particles. The other family is the family of quarks. The theory which describes these families and the forces between them is called The Standard Model. We will look at these families later in this resource. | | | |
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