Lesson Plan : Electron Configuration

Teacher Name:
  Bonnie Stevenson-Tapper
 Grade 11-12

 A set of three rules can be used to determine the electron arrangement of 90% of the elements.
  Aufbau Principle - the German word aufbauen, which means to build up. This principle states that each electron occupies the lowest energy orbital available. Pauli Exclusion Principle - states that a maximum of two electrons can occupy single atomic orbital, but only if the electrons have opposite spins. Hund's Rule - states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbital(every one gets a candy bar, before you get seconds.) Quantum number, orbital diagram, electron configuration, and ion.
 National Standards: UCP.1, UCP.2; A.1, A.2, B.1, B.6, E.2, F.6, G.2 G.3. St.Paul Public School: Atomic Structure
 Apply the Pauli exclusion principle, the aufbau principle and Hund's rule to write electron configurations using orbital diagrams, and electron configuration.
 Aufbau Diagram Cards (one for each group) Practice Problem Cards PowerPoint Presentation introducing the 3 principles.
 Have students draw the basic electron energy model diagrams for elements H, He, and Li. This exercise is a review for the concept of electrons located in specific areas away from the nucleus, as well as, checking for studentsf prior understanding.
 Review and highlight previous information: Bohr related movement of electrons in a circular path (orbit), and he assigned a number called a quantum number (1-7) to each orbit. Continue to explain that electrons closest to the nucleus have the lowest energy, and energy increases as you move away. Have students verbally explain their drawings using the vocabulary, quantum number, and locate lowest and higher energies. Next introduce the new ideas: Pauli Exclusion Principle, electrons can spin in one of two directions. In chemistry we use arrows ª« to represent spin directions, and a box to represent an orbital. Write the ways the orbital will look, unoccupied orbital (empty box), a filled orbital (2 arrows in opposite directions), and both ways a half filled orbital. Now explain the Aufau diagram (have fun with the name, it helps the students remember the term). Give them the s, p, d, and f sublevels. Then using the Pauli Exclusion Principle have the students calculate how many boxes each sublevel will contain. Stress no matter what the quantum number is with the sublevel that the sub levels will always have 1, 3, 5 and 7 boxes. Now give them the diagram, and have the students crate the electron configurations for H, He, and Li. Once they have the configurations, create the orbital diagrams introduce the last concept, Hundfs Rule. That each orbital of equal energy needs to get one electron, same direction, before the orbital can have a second electron. This is the sharing of candy, before taking seconds.
 Have the students make an electron configuration, and orbital diagram of the element Ti. When they are finished have them explain using the new terms, and show them how to check the electron configuration in the Handbook of Chemistry. Usually I have copies for the students to use. They should notice a difference between the electron configuration and the filling of the aufbau diagram.
 Make a foldable to help summarize the three rules that define how electrons are arranged in an atom. Fold a piece of paper in half making the back edge about 2 cm longer than the front edge. Fold in thirds and then cut along the folds in front. Write the words gElectron Configurationh on top of back, and the one concept (Aufbau Principle, Pauli Exlcusion Principle,, and Hundfs Rule) on each flap. Students can use to help explain their diagrams.
Checking For Understanding:
 When the group is comfortable with configuration and orbital diagrams, I give them ion cards. The topic of ions was previously covered, so students have to dig into their memories and translate the Na+, or a Cl-. These cards read gGive the electron structure for Ni+2.h
 Have student volunteers do a variety of problems on the board, and have the students explain the process they used to solve the problems. Use this time to clear any misconceptions. Also stress to the students the need for atoms to be stable to highlight the gbehaviorsh of ions.
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