1. Bohr-Rutherford Diagrams

2. One particle picture represents one atom
An atom has a structure of its own and we can look closely at it

3. Atomic Structure
The atom is made up of protons and neutrons (in the nucleus) and electrons (‘floating’ around the nucleus)
Particle
Charge
Location
Short Form
Proton
Neutron
Electron

4. Particle
Charge
Location
Short Form
Proton +
Nucleus p+
Neutron
neutral n0
Electron -
Orbits e-

5. Bohr-Rutherford Diagrams
A diagram showing the structure of the atom
Neils Bohr
Discovered that there are negatively charged particles moving around the nucleus of the atom in ‘shells’
Ernest Rutherford
Discovered that the nucleus of the atom was mostly positive (because of the protons)

6. Electrons (Negative Charge)
ENERGY LEVELS
1st shell (2 electrons)
2nd shell (8 electrons)
3rd shell (8 electrons)
4th shell (18 electrons)
Protons
Neutrons
Nucleus
(Positive Charge)
Electrons (Negative Charge)

7. Important Things to Remember
The # of protons determines which element is represented
The # of electrons can change but the # of protons CANNOT change
Electrons travel in energy levels
The outer most level is called the valence shell
Atoms ‘wish’ to be ‘stable’ by having a full valence shell

8. Standard Notation 11 Na
22.99

9. Element symbol (Sodium)
Standard Notation 11 Na
22.99
Element symbol (Sodium)

10. Element symbol (Sodium)
Standard Notation
Atomic # 11 Na
22.99
Element symbol (Sodium)

11. Element symbol (Sodium)
Standard Notation
Atomic # 11 Na
22.99
Element symbol (Sodium)
Atomic Mass

12. Helpful Hints
Atomic # = # of Protons # of Protons = # of Electrons # Neutrons = Atomic Mass – Atomic #

13. Let’s go back to Sodium…11 Na
22.99

14. Let’s go back to Sodium…11 Na
22.99
# p+ =
# n0 =
# e- =

15. Let’s go back to Sodium…11 Na
22.99
# p+ = 11
# n0 = (23-11) = 12
# e- = 11

16. Let’s go back to Sodium…
# p+ = 11
# n0 = (23-11) = 12
# e- = 11

17. Let’s go back to Sodium…
# p+ = 11
# n0 = (23-11) = 12
# e- = 11

18. Let’s go back to Sodium…
# p+ = 11
# n0 = (23-11) = 12
# e- = 11

19. Let’s go back to Sodium…
# p+ = 11
# n0 = (23-11) = 12
# e- = 11

20. Let’s go back to Sodium…
# p+ = 11
# n0 = (23-11) = 12
# e- = 11

21. Let’s go back to Sodium…
# p+ = 11
# n0 = (23-11) = 12
# e- = 11

22. Let’s go back to Sodium…
# p+ = 11
# n0 = (23-11) = 12
# e- = 11

23. Let’s go back to Sodium…
# p+ = 11
# n0 = (23-11) = 12
# e- = 11