Electron Configurations 3 Types Electron Configuration Notation Shorthand Notation Orbital Notation

Electrons: or superscripts Orbitals: or ____ Symbols Electrons: or superscripts Orbitals: or ____ Spin of electrons will be represented by the direction of the arrow

Each orbital can hold at most 2 electrons. Every s sub levels have only 1 orbital = p sublevels have 3 orbitals = d sublevels have 5 orbitals = f sublevels have 7 orbitals = Total of 2e- 6 10 14

Key Terms Ground State: refers to electrons having the lowest possible energy Excited State: refers to electrons having gained energy. An excited electron will return to its ground state and when it does it will emit light. Quantum numbers: specifies the properties and location of an electron

Quantum numbers n refers to the energy level; n can be 1-7 l refers to the sublevel and describes the shape of the orbital. l can be 0-3 with 0 representing s shaped orbitals, 1 representing p shaped orbitals, 2 representing d shaped orbitals 3 representing f shaped orbitals m refers to magnetic quantum number or refers to the spin of the electron

Electron Configuration….. …. refers to the distribution of electrons among orbitals of an atom. ….is determined by distributing electrons among levels, sublevels and orbitals according to these rules: Aufbau Principle Pauli Exclusion Principle Hund’s Rule

The Rules for Electron Configurations Aufbau Principle: Electrons are added one at a time to the lowest energy orbitals until all electrons have been included. “Lazy Tenant Rule”

Rules (cont’d): Pauli Exclusion Principle Each orbital can hold at most 2 electrons; when the orbital holds 2 electrons they will have opposite spins.

Rules (cont’d) WRONG RIGHT Hund’s Rule: each orbital of a sublevel must have at least one electron before adding a second electron Within a sublevel, place one e- per orbital before pairing them. “Empty Bus Seat Rule” WRONG RIGHT

Orbital Filling Order This diagram shows how the complex orbitals of large atoms overlap and fill “out of order.” You should memorize the patterns shown in the diagram and be able to redraw it without looking at it.

To write the orbital notation for Vanadium: To write the electron configuration notation for Vanadium:

Electron configuration demonstrations http://intro.chem.okstate.edu/WorkshopFolder/Electronconfnew.html

Orbital Diagrams 1s 2s 2p H Electron Configuration 1s1

Write the orbital notation for silver. 2. Write the electron configuration for silver.

Orbital Diagrams

Orbital Diagrams

Orbital Diagrams Your turn….. Practice on worksheet

Writing Electron Configurations H 1s1 He 1s2 Li 1s2 2s1 C 1s2 2s2 2p2 S 1s2 2s2 2p6 3s2 3p4

Exceptions to the Aufbau Principle Recall that some orbitals are very close in energy. This is especially true for large atoms having lots of d and f orbitals. This causes certain orbitals to fill before one would normally expect. Chromium and Copper illustrate the exceptions (page 153). A certain amount of energy stability results from half-filled orbitals, and this accounts for the orbital filling order in Cr and Cu.

Exceptions Chromium Instead of: Copper 1s2 2s2 2p6 3s2 3p6 4s2 3d4

Periodic Table vs. Configurations Last electron filling . . . http://www.uky.edu/~holler/html/orbitals_2.html

The Periodic Table- e configuration

CONGRATULATIONS! WOW! We sure covered a lot of territory! You have finished a very important, concept in Chemistry. CONGRATULATIONS!