1. Unit 6, Lesson 4: Electron Configurations

2. Core Notation
Core notation represents the electron configuration for all of the inner shell (core) electrons using the symbol for the last noble gas before the atom. The outer shell electrons are represented as usual.
Examples: Al, Kr
Practice: Pg. 156 #27 (a, c, e, etc.)
20 min

3. Brain Break!

4. Special Exceptions
A filled or half-filled d-subshell is especially stable!
Thus, an atom or ion that is one electron short of a d5 or d10 configuration will “borrow” an electron from the nearest s-orbital in order to gain stability.
Hence, 4s23d4 becomes 4s13d5, and
4s23d9 becomes 4s13d10.

5. Electron Configurations of Ions
For negative ions, simply add electrons to the subshells, continuing from where the neutral atom left off.
For positive ions, remove p, s, and then d electrons!
Examples: O2-, Sn4+
Practice: Pg. 157 #28 (a, c, e, etc.)
20 min