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electron-configuration-7

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									Section 11.4
Electron Configurations and Atomic Properties
Objectives
1. Relate the Aufbau Principle, Hund’s Rule, and Pauli’s
   Exclusion Principle to the way in which electrons in
   atoms fill energy levels.

2. Locate and name the four blocks (s, p, d, & f) of the
   periodic table and explain the reasons for these names

3. Write out electron configurations, orbital notation, and
   noble gas configuration for various elements and relate
   it back to their behavior, frequency, wavelength, and
   energy.
Section 11.4
Electron Configurations and Atomic Properties
               Electron Configurations:
          Arrangement of electron in an atom.

 • Order of increasing energies for atomic orbitals:

 • Rules:
    – Aufbau Principle
    – Pauli’s Exclusion Principle
    – Hund’s Rule
Section 11.4
Electron Configurations and Atomic Properties
B. The Wave Mechanical Model: Further Development

    Atoms Beyond Hydrogen
• Pauli Exclusion Principle - No 2electrons in the same atom can have
  the same set of 4 quantum numbers. An atomic orbital can hold a
  maximum of 2 electrons and those 2 electrons must have opposite spins

• Hund’s Rule – every orbital in a subshell is singly occupied with one
  electron before any one orbital is doubly occupied, and all electrons in
  singly occupied orbitals have the same spin.

• Aufbau’s Principal – An electron occupies the lowest energy orbital
  that can receive it, then it will go back and pair up.
Section 11.4
Electron Configurations and Atomic Properties

               Electron configuration Notation:

• Number of electron in a sublevel is shown by adding a
  superscript to the sublevel designation.

• We can use the structure of the periodic table to predict
  the filling order of the subshells when we write the
  electron configuration of an element.

• As you move across the block of two columns,
  electrons are added to an s subshell that has a
  principal quantum number equal to the period number.
Section 11.4
Electron Configurations and Atomic Properties
B. Electron Configurations and the Periodic Table
Section 11.4
Electron Configurations and Atomic Properties
A. Electron Arrangements in the First 18 Atoms on the
Periodic Table
• H atom
   – Electron configuration – electron arrangement – 1s1
   – Orbital diagram – orbital is a box grouped by sublevel
     containing arrow(s) to represent electrons
Section 11.4
Electron Configurations and Atomic Properties

                     Orbital Notation:


• Unoccupied orbital is represented by a line, with the
  orbital’s name written underneath the line.



• EX: Hydrogen and Helium
Section 11.4
Electron Configurations and Atomic Properties
A. Electron Arrangements in the First 18 Atoms on the
Periodic Table
• He atom
   – Electron configuration– 1s2
   – Orbital diagram
Section 11.4
Electron Configurations and Atomic Properties
A. Electron Arrangements in the First 18 Atoms on the
Periodic Table
• Li atom
   – Electron configuration– 1s2 2s1
   – Orbital diagram
Section 11.4
Electron Configurations and Atomic Properties
A. Electron Arrangements in the First 18 Atoms on the
Periodic Table
Section 11.4
Electron Configurations and Atomic Properties
A. Electron Arrangements in the First 18 Atoms on the
Periodic Table
   Classifying Electrons
• Valence electrons – electrons in the outermost (highest)
  principal energy level of an atom

• Core electrons – inner electrons

• Elements with the same valence electron arrangement show
  very similar chemical behavior.
Section 11.4
Electron Configurations and Atomic Properties
B. Electron Configurations and the Periodic Table

• Orbital filling and the periodic table
Section 11.4
Electron Configurations and Atomic Properties

                     Noble-Gas Notation:

 • The first ten electrons in an   •   See Lecture Ex
   atom of each of the 3rd
   period elements have the
   same configuration as neon.
   We can use a shorthand
   notation for the electron
   configurations of the third-
   period elements.

 • Outer main energy level is
   fully occupied, by eight
   electrons (octet rule)

 • Helium – not

								
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