Section 5.2 Lecture for Honors & Prep Chemistry

1. Bellwork- draw orbitals
Draw the following atomic orbitals
to scale
1s
2s
3s
three 2p orbitals
Three 3p orbitals

3. Electron configurations show
where each electron in an atom is
located.
Three rules —the aufbau
principle, the Pauli exclusion
principle, and Hund’s rule— tell
you how to find the electron
configurations of atoms.

4. According to the aufbau principle,
electrons occupy the orbitals of
lowest energy first.
In the aufbau diagram below, each box
represents an atomic orbital.

5. The higher an orbital is on the
orbital chart, the higher its energy,
so orbitals fill from bottom to top.

6. According to the Pauli exclusion
principle, an atomic orbital may
hold at most two electrons. To
occupy the same orbital, two electrons
must have opposite spins.
 
1 e- in this orbital 2 e-

7. Hund’s rule states that electrons occupy
orbitals of the same energy in a way that
makes the number of electrons with the
same spin direction as large as possible.
For orbitals of equal energy, 1 e-
per orbital before you double up!
3p  NOT 3p 

8. Fill in an orbital diagram for
phosphorus, boron and silicon.
Energy level # of e- in that
sublevel
sublevel type

9. Fill in an orbital diagram for
phosphorus, boron and silicon.
Energy level # of e- in that
sublevel
P 1s2 2s2 2p6 3s2 3p3
sublevel type
The superscripts will add up to the
number of e- in the atom.