1. Drawing a Bohr-Rutherford Diagram

2. History Ernest Rutherford discovered that atoms contained a small dense positively charged nucleus surrounded by negatively charged electrons Niels Bohr discovered that electrons travelled in distinct orbits around the nucleus

3. Bohr-Rutherford Diagram A Bohr-Rutherford Diagram illustrates a model of a single atom of an element. It shows how many protons, neutrons and electrons the atom has and shows where these subatomic particles are located.

4. Drawing a Bohr-Rutherford Diagram Before you begin, you must figure out how many protons, neutrons and electrons the atom has. Remember: –the number of protons is equal to the atomic number –the number of electrons is equal to the number of protons (the atom is neutral)

5. Calculating the number of neutrons The number of neutrons is equal to the atomic mass - (minus) the atomic number. This is because protons and neutron each weigh 1 amu and the entire mass of the atom is made up of the protons plus the neutrons (electrons weigh virtually nothing)

6. Example: draw the Bohr-Rutherford Diagram for carbon C 12.01 6 C 12 6 Standard Atomic Notation A square on the periodic table # protons (p + ) = 6 #electrons (e - ) = 6 # neutrons (n 0 ) = 12 - 6

7. Drawing the nucleus The protons and the neutrons are found in the nucleus of the atom. Draw a circle to represent the nucleus and write in the number of protons and neutrons E.g. for carbon: 6p + 6n 0

8. Adding the electrons The electrons are found spinning in orbits around the nucleus. The first orbit can hold only 2 electrons The second and third orbits can hold up to 8 electrons

9. Adding Electrons to your Diagram Fill each orbit before you move to the next The outer orbit is called the valence orbit The electrons in the valence orbit are the ones that are involved in chemical reactions

10. Bohr-Rutherford Diagram for Carbon 6p + 6n 0 electrons nucleus