We call these letters symbols. And an element is a pure substance made from only one type of atom. And there are quite a lot of elements. There are something like 100, and each has a unique symbol ...

Symbol: A one or two-letter abbreviation used to represent the element. Atomic number: The number of protons in the nucleus of an atom of the element. These rules help in identifying and writing ...

This symbol shows that chlorine has 35 particles ... as the number of electrons and protons are equal in a neutral atom, chlorine also has 17 electrons. The relative mass of a nucleus is the ...