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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
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 thirdperiod elements.
• Outer main energy level is
fully occupied, by eight
electrons (octet rule)
• Helium – not
•
See Lecture Ex