1. II. Electron Cloud Model
Ch Atomic Structure
II. Electron Cloud Model
(p )
Orbital
Energy Levels
Bohr Model Diagrams

2. A. Orbital
Region where there is 90% probability of finding an electron.
Can’t pinpoint the location of an electron.
Density of dots represents degree of probability.

3. A. Orbital
Orbitals have different shapes.

4. B. Energy Levels Electrons can only exist at certain energy levels.
Low energy levels are close to the nucleus.
Each energy level (n) can hold 2n2 electrons.

5. C. Bohr Model Diagrams
Simplified energy levels using Bohr’s idea of circular orbits.
Can replace with: 3p 4n
Lithium
Atomic #: 3
Mass:
# of p: 3
# of e: 3
# of n: 4 e- e- p n
Maximum e-
Level 1 2e-
Level 2 8e-
Level 3 18e-
Level 4 32e- e-

6. Valence Electrons Valance Electrons
Number of electrons in outermost energy level
Tells how an element behaves

7. B. Periodic Trends Group # = # of valence e- (except He)
Ex: Ca is in group 2 so it has 2 valence e-
Families have similar reactivity.
Period # = # of energy levels 1A 2A
3A 4A 5A 6A 7A 8A

8. Lewis Dot Structures

9. C. Bohr Model Activity Choose a number between 1 & 18.
Find your element by the atomic number you picked.
Draw a Bohr Model diagram for your element on your marker board.
Round off the mass listed on the table and subtract the atomic # to find the # of neutrons.
Abbreviate the # of ‘p’ and ‘n’ in the nucleus.
Have a partner check your drawing.
Repeat with a new element.