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# Section 5.3 PowerPoint PPT Presentation

Section 5.3. Electron Configurations. Electron Configurations. Atom is in the ground state 3 rules or laws Aufbau principle Pauli Exclusion principle Hund’s Law. Aufbau Principle. Electrons occupy lowest energy orbital available All orbitals of a sublevel are equal energy

Section 5.3

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## Section 5.3

Electron Configurations

### Electron Configurations

• Atom is in the ground state

• 3 rules or laws

• Aufbau principle

• Pauli Exclusion principle

• Hund’s Law

### Aufbau Principle

• Electrons occupy lowest energy orbital available

• All orbitals of a sublevel are equal energy

• Sublevels have different energies

• s < p < d <f

• Orbitals within one principal energy level can overlap orbitals of another

### Electron Filling Order

Which orbital will fill first, 4s or 3d?

### Pauli Exclusion Principle

• Maximum of 2 electrons in an orbital, but only if they have opposite spin.

### Hund’s rule

• Electrons with same spin must occupy each equal energy orbital before additional electrons with opposite spins can occupy the same orbital.

### Orbital Filling Order

1s 2s 2p 3s 3p 4s

3d 4p 5s 4d 5p 6s

4f 5d 6p 7s 5f 6d 7p

### Electron Configurations

• Three methods

1. Electron Configuration Notation

2. Noble Gas Notation

3. Orbital Diagrams

### Electron Configuration Notation

• Ex: N

• # of electrons?

• Start with the lowest energy, fill to capacity, go to next lowest energy, etc. Stop when you run out of electrons.

• Superscripts = total electrons

### Electron Configuration Notation

• You try … Zinc

### Electron Configuration Notation

1s2 2s22p6 3s23p6 4s23d10

### Assignment

• Write the electron configuration notation for the following elements:

• Boron (B), Neon (Ne), Sulfur (S), Magnesium (Mg), Vanadium (V), Silver (Ag)

### Noble Gas Notation

• Shorthand

• Find the noble gas closest to the element (without going over).

• Ex: For Gold (79): Xenon (54)

• We write [Xe] and start counting from there

• The first orbital after xenon is 6s

### Noble Gas Notation

• [Xe]6s2 4f14 5d9

• Check: (Xe’s atomic number) 54 + 2 + 14 + 9 = 79 (gold’s Atomic number)!

• Silver

• P.147 #79

### Orbital Diagrams

• Draw a line for each orbital

• Designate each electron with an arrow

• = orbital with 1 electron

• = orbital with 2 electrons

### Orbital Diagrams

• Nitrogen: 1s22s22p3

• Write notation of N

• Then we fill them with electrons using the Aufbau principle, Pauli exclusion principle, and Hund’s law

### Orbital Diagrams

• You try another example: Cu

### Assignment

• Draw orbital diagrams for beryllium, aluminum, nitrogen, and sodium, manganese, germanium, and europium.

### Electron Dot Structures

• Valence electrons

• Electrons in outermost energy level.

• Responsible for chemical properties

### Electron Dot Structures

• Valence electrons only

• Place ‘dots’ around element symbol

• 4 sides of element = orbitals

• Fill these orbitals one at a time (Hund’s)

### Assignment

• P.141 #23(yellow box), 26, 28

• P.147 #81