118 Elements and Their Symbols and Atomic Numbers: The periodic table is a well-organized chart that contains all the known elements in the universe. These elements are building blocks of matter ...

Atoms are very small. They have a radius of around 1 × 10 10 metres. This symbol shows that chlorine has 35 particles in the nucleus (protons and neutrons), 17 of which are protons. It also tells ...

The proton number (Z) of an atom is the number of protons it contains. All the atoms of a particular element have the same proton number (number of protons). The atoms of different elements have ...