1. Atomic Structure

2. The Atoms Family
Atom: the smallest part of an element. Name means “indivisible”

3. Who’s atom is it? Dalton (bb) Rutherford Electron cloud model Thompson
(Plum Pudding)
Bohr
(planetary)
Standard Model

4. Parts of an Atom
Nucleus:The main center of an atom. Made up of protons and neutrons
Proton:In the nucleus. Has a + charge. Atomic number tells the number of protons
Neutron:In the nucleus. Has NO charge. Is there to keep protons apart

5. Parts of an ATOM
Electrons: In the electron cloud, has a negative charge.

6. The Same, But Different
Isotopes:An element with different numbers of neutrons.
Atomic mass - atomic number = number of neutrons.
Example: Hydrogen (mass) - 1 (atomic #) = neutrons
Having an unequal number of neutrons and protons can make an atom unstable!

7. B. Subatomic Particles Most of the atom’s mass. Atomic Number
NUCLEUS
ELECTRONS
PROTONS
NEUTRONS
NEGATIVE CHARGE
POSITIVE CHARGE
NEUTRAL CHARGE
Most of the atom’s mass.
Atomic Number
equals the # of...

8. Let’s review
Name the two sub-atomic particles found in the nucleus of an atom:
Proton and Neutron
What is the charge of a proton?
Positive
What is the charge of a neutron?
No charge (neutral)
Where are the electrons at?
Orbiting the nucleus

9. II. Electron Cloud Model Orbital Energy Levels Bohr Model Diagrams
Atomic Structure
II. Electron Cloud Model
Orbital
Energy Levels
Bohr Model Diagrams

10. Niels Bohr (1913) Bright-Line Spectrum
tried to explain presence of specific colors in hydrogen’s spectrum
Energy Levels
electrons can only exist in specific energy states
Planetary Model
Niels Bohr (1913)

11. Demonstration Time

12. Niels Bohr (1913) Planetary Model:
Bright-line spectrum
Planetary Model:
electrons move in circular orbits within specific energy levels

13. electron shells
Electrons different amounts of energy and at different energy levels or electron shells.
Electron shells (levels) determine… how an atom behaves when it encounters other atoms

14. Levels
1st Level: closest to nucleus. Has 1 orbital. Can hold 2 electrons
2nd level: next one out. Has 2 orbitals. Can hold 8 electrons.
3rd level: Holds 8 electrons.
4th level: Holds 18 electrons

15. Why are electrons important?
Elements have different electron configurations so different levels of bonding
Valence electrons are the electrons in the outer most shell.
Valence electrons are important because they affect how the element reacts with other elements.

16. How many valence electrons
are in these different atoms?

17. Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons
C would like to
N would like to
O would like to
Gain 4 electrons
Gain 3 electrons
Gain 2 electrons

18. Ne C. Stability Octet Rule
most atoms form bonds in order to have 8 valence e-
full outer energy level
like the Noble Gases! Ne
Stability is the driving force behind bond formation!

19. Electron Dot Structures
Symbols of atoms with dots to represent the valence-shell electrons
H He:
          
Li Be  B   C   N   O  : F  :Ne :
       
          
Na Mg  Al  Si  P S :Cl  :Ar :
       

20. Learning Check A. X would be the electron dot formula for
A. X would be the electron dot formula for
1) Na 2) K 3) Al
 
B  X  would be the electron dot formula
1) B 2) N 3) P

21. Stability Why is it important for an atom to be “stable”?
So it is less reactive.
Why are noble gases stable?
They have a full energy level.