Bohr Diagrams!

It all begins with atoms. Atoms are electrically neutral because they have the same number of electrons(-) and protons(+). They also have neutrons which are not electically charged at all.One way we can show how many electrons and protons are in an atom is by making a Bohr Diagram or an energy level model.

A Bohr Diagram basically shows you how many electrons are in an atom and where they are placed. We use energy levels to show the placement of these electrons, with 2 electrons in the first level, 8 in the second, 8 in the third, and 18 in the fourth. To find out how many electrons are in an atom, we look at the atomic number

The atomic number tells us the number of protons in an atom, in this case 47. Since an atom is electronically neutral, there must also be 47 electrons.

This is a Bohr Diagram of an Aluminum atom. There are 13 protons in an aluminum atom and  therefore 13 electrons. We put 2 electrons in the first level, filling it up. Then we fill the second level with 8 electrons and then 3 in the next to make 13.

Some atoms have full outside levels, called valence shells. When an atom has a full valence shell it is very stable. Noble gases are the only atoms that naturally have full valence shells.


The other way of showing how many electrons are in an atom is by making an energy level model.
This looks sort of like a Bohr Diagram but instead of drawing the electrons, we simply write the number of electrons above the nucleus.

                                                2e-
                                                8e-
                                                8e-
                                                2e-
                                                20p
                                                20n

This is just a simpler way of communicating how many electrons there are and how many energy levels or shells are being used.