1. Atomic Structure

2. The Structure of the Atom
The Ancient Greeks used to believe that everything was made up of very small particles. I did some experiments in 1808 that proved this and called these particles ATOMS:
John Dalton
ELECTRON – negative, mass nearly nothing
PROTON – positive, same mass as neutron (“1”)
NEUTRON – neutral, same mass as proton (“1”)

3. The Nucleus is made of Protons and Neutrons
The Atom
Electron
Nucleus
Shell or Orbit

4. Hydrogen has one proton, one electron and NO neutrons
The Hydrogen Atom
Hydrogen has one proton, one electron and NO neutrons
Proton
Electron

5. Helium has two electrons, two protons and two neutrons
The Helium Atom
Helium has two electrons, two protons and two neutrons
Proton
Electron
Neutron

6. Sub-Atomic Particles 2 He 4 Particle Mass Charge Proton 1 Neutron
Electron -1
ATOMIC NUMBER = number of PROTONS He 2 4
SYMBOL
MASS NUMBER = number of PROTONS + number of NEUTRONS

7. The Helium Atom 2 He 4 Proton Electron Neutron
Atomic Number 2 = 2 Protons 2 He 4
Atomic Mass 4 = 2 Protons + 2 Neutrons

8. The number of Protons is ALWAYS equal to the number of ELECTRONS
# Protons = # Electrons
The number of Protons is ALWAYS equal to the number of ELECTRONS Li
3 + Protons
3 - Electrons

9. Electron Orbit: Bohr Model
Electrons have fixed orbit ‘shells’
The first shell can carry TWO electrons
All other shells can carry EIGHT electrons at most

10. Valence Electrons
Valence Electrons are located on the OUTERMOST Shell, and determine how REACTIVE an element is

11. The Atom Li - Lithium Li has 3 protons, 3 electrons, and 4 Neutrons

12. Boron has five protons, five electrons and six neutrons.
The Atom B - Boron
Boron has five protons, five electrons and six neutrons.
Electrons
Protons
Neutrons

13. Carbon has six electrons, six protons and six neutrons.
The Atom C - Carbon
Carbon has six electrons, six protons and six neutrons.
Electrons
Protons
Neutrons

14. The Atom N - Nitrogen
Nitrogen has seven electrons, seven protons and seven neutrons.
Electrons
Protons
Neutrons

15. The Atom O - Oxygen
Oxygen has eight electrons, eight protons and eight neutrons.
Electrons
Protons
Neutrons

16. The Atom Na - Sodium
Sodium has eleven electrons, eleven protons and twelve neutrons.
Electrons
Protons
Neutrons

17. How many protons, neutrons and electrons?1 5 8
P = 5
N = 6
E = 5
P = 8
N = 8
E = 8
P = 1
N = 0
E = 1 H B O 1 11 16 92 11 17
P = 11
N = 12
E = 11
P = 92
N =146
E = 92
P = 17
N = 18
E = 17 Na Cl U 23 35
238

18. WORKSHEET TIME!
Front Side Only 

19. This makes their MASS different.
Isotope
Atoms that have the same number of protons but different numbers of neutrons.
This makes their MASS different.

20. Describe Isotope Example: