# The Downfall of Classical Physics - PowerPoint PPT Presentation

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The Downfall of Classical Physics. Niels Bohr – Quantum Mechanics. Niels Bohr applies Quantum Mechanics to Rutherford’s model and proposes that electrons are located around the nucleus in energy levels. . The Rise of Quantum Physics.

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The Downfall of Classical Physics

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### Niels Bohr – Quantum Mechanics

Niels Bohr applies Quantum Mechanics to Rutherford’s model and proposes that electrons are located around the nucleus in energy levels.

### The Rise of Quantum Physics

Spectral lines can be explained by the movement of electrons from one energy level to another.

### ENERGY LEVEL (n)

• “Rings” of Bohr’s planetary model

• 7 possible energy levels

• Maximum number of electrons in each energy level = 2n2

• 1st level:

• 2nd level:

• 3rd level:

2

8

18

### ENERGY SUBLEVELS

• 4 types of sublevels:

• s

• p

• d

• f

• Every energy level begets a new sublevel

• Energy level 1: 1 sublevel (s)

• Energy level 2: 2 sublevels (s, p)

### ORBITALS

• s sublevel = 1 s orbital

• p sublevel = 3 p orbitals

• d sublevel = 5 d orbitals

• f sublevel = 7 f orbitals

• “Spin up”

• “Spin down”

### RULES FOR ELECTRONS

• An orbital can hold a maximum of TWO electrons

• Pauli exclusion principle

• Aufbauprinciple

• Hund’s rule

### Pauli Exclusion Principle

• no two electrons can have the same “address”

• Energy level

• Sublevel

• Orbital

• Spin

### AufbauPrinciple

• Electrons will fill the orbitals with the lowest amount of energybefore filling in orbitals that have more energy

• Order is: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p

### Hund’s Rule

• Electrons will not share an orbital of the same energy if there is an empty orbital with that energy is available

Orbital

Spin

1

s

Energy level

Sublevel

1s

2s

2p

### How to draw orbital diagrams

• Use periodic table to figure out where to end (energy level and sublevel of last electron)

• Draw boxes (orbitals) for all energy levels and sublevels up to the ending point

• 1 box for s, 3 boxes for p, 5 boxes for d, 7 boxes for f

• Fill boxes with electrons (2 per orbital) with opposite spins

• Follow Hund’s rule when in the p, d, or f sublevels

### Electron configurations

• Based on orbital diagrams

• Use numbers and superscripts along with s, p, d and f to show location of electrons in atoms

• Coefficient = energy level

• Letter = sublevel

• Superscript = # of electrons in sublevel

### Example:

Energy level2 electrons

1s2

sublevel

1s

2s

2p

1s22s22p3

### Practice

• Draw the orbital diagram for oxygen

• Write the electron configuration for oxygen

1s

2s

2p

1s22s22p4

### Shortcuts!!

• Shortcut (shortened) Notation:

• Use closest Noble Gas before the element

• For bromine:

• Closest Noble Gas before the element:

• Argon:

• Shortcut Notation:

1s22s22p63s23p6

4s23d104p5

1s22s22p63s23p6

[Ar] 4s23d104p5b

### What is the electron configuration of potassium?

• 1s22s22p63s23p63d1

• 1s22s22p23s23p24s1

• 1s22s22p63s23p3

• 1s22s22p63s23p64s1

Each period number in the periodic table corresponds to _______A)an atomic massB)an energy level

C)an energy sublevelD)an atomic number