Electrons

Bohr Model

We know that the nucleus contains protons and neutrons. The electrons orbit the nucleus in fixed paths called energy levels or shells.

Each shell can hold a certain number of electrons:

• 1st shell = 2 electrons

• 2nd shell = 8 electrons

• 3rd shell = 8 electrons

• Electrons fill from the inside out

• If you're writing out the configuration, use this format: 2,8,1 (example for sodium).

Things to Remember

​Can you guess what element this is?

Time to practise:

1. In pairs, grab a whiteboard and marker.

2. I will tell you an element, and the first group to successfully do all of the following win a stripe.

​You need to include:

• Atomic Number

• Atomic Mass

• A correct Bohr diagram, including all subatomic particles

1. Cut out the worksheet and glue it into your books.

2. Complete the Bohr models for the first 20 elements.

​

In your books: