Download e- are outside nucleus nucleus

I. Models of the Atom
• Rutherford Model (Early 1900’s)
e- are outside nucleus
nucleus: dense; contains
p+; positive charge
• Bohr Model (Early 1900’s)
o Quantum: A fixed amount of energy needed to move
an e- from one energy level to the next
e- travel in
Orbits: circular paths
around the nucleus
Nucleus: dense; positive;
also contains n0
• Quantum Mechanical Model (~1926 *Currently Accepted*)
• Mathematical equation describes the
location & energy of e- in atom
• Similar to Bohr model:
- nucleus,
- quantized energy levels)
• Difference: e- do not travel in fixed
paths; they exist in an e- cloud
e- cloud: region around the nucleus
where the probability of finding an
e- is about 90%
• PRINCIPLE ENERGY LEVEL:
- Areas around the nucleus where the atomic
orbitals exist
- The further an energy level is from the
nucleus, the higher in energy it is
• ATOMIC ORBITALS: - Regions around the nucleus where e- are
likely to be found (probability is ~ 90%)
- Specific types of e- clouds
- Shapes come from mathematical equations
Types of Orbitals: s, p, d, f
Pauli Exclusion Principle: An orbital can hold at most two electrons
S ORBITALS:
• spherical in shape
• 1 “s orbital” per energy level
• start at the 1st energy level
• s electrons = 1 s orbital x 2 e- = 2 s e-
P ORBITALS:
• dumbbell shaped
• 3 “p orbitals” per energy level
• start at the 2nd energy level
• p electrons = 3 p orbitals x 2 e- = 6 p eD ORBITALS:
• clover shaped
• 5 “d orbitals” per energy level
• start at the 3rd energy level
• d electrons = 5 d orbitals x 2 e- = 10 d e-
F ORBITALS:
• complex in shape
• 7 “f orbitals” per energy level
• start at the 4th energy level
• f electrons = 7 f orbitals x 2 e- = 14 f eSummary of Principal Energy Levels and Orbitals
Principle Energy Level
1st
2nd
3rd
4th
5th and beyond
Type(s) of Orbitals
s
s, p
s, p, d
s, p, d, f
s, p, d, and f orbitals all exist
II. Electron Arrangement in Atoms
• ELECTRON CONFIGURATIONS:
- tell how electrons are arranged in atomic orbitals (1s22s22p6)
• AUFBAU PRINCIPLE:
- states that e- enter the lowest energy orbitals 1st
• DIAGONAL RULE:gives orbitals in order of lowest to highest energy
start
1s
2s
3s
4s
5s
6s
7s
2p
3p
4p
5p
6p
7p
3d
4d
5d
6d
7d
4f
5f
6f
7f
STOP HERE