Section 5.3

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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

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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

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)!
Assignment
• 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