The Structure of an Atom

Everything is made up of atoms. Atoms are the building blocks of all materials. Atoms are tiny. The diagram to the right shows the structure of an atom:

Atoms have a nucleus which is surrounded by electrons.

The nucleus contains neutrons (which have no charge) and protons (which have a positive charge).  

The electrons which surround the nucleus carry a negative charge.

The electrons occupy shells. The shell closest to the neutron has the lowest energy level and can only carry two electrons.  The second and third shells can carry eight electrons.

The diagram shows a Carbon atom. 

Carbon has the atomic number 6. The atomic number tells you the number of protons and electrons the atom has.

On the diagram we can see two electrons in the shell closest to the nucleus and 4 electrons in the second shell (giving a total of 6 electrons). The electronic structure of Carbon is 2, 4.