Title: Lesson 6 Electron Configurations of Ions Learning Objectives: Know how to write full electron configurations of ions using ideas of subshells

Recap – Rules for drawing electron configuration THE AFBAU (BUILDING UP) PRINCIPLE “Electrons enter the lowest available energy level.” PAULI’S EXCLUSION PRINCIPLE “Max number in each orbital is 2. Must have opposite spins.” HUND’S RULE OF MAXIMUM MULTIPLICITY “When in orbitals of equal energy, electrons will try to remain unpaired.” Starter Activity

ELECTRONIC CONFIGURATION OF IONS Positive ions (cations) are formed by removing electrons from atoms. Negative ions (anions) are formed by adding electrons to atoms. Electrons are removed first from the occupied orbital of highest energy. Ions of s and p block elements are ‘isoelectronic’ with a noble gas but contain a different number of protons and are charged. SODIUM Na1s 2 2s 2 2p 6 3s 1 Na + 1s 2 2s 2 2p 6 1 electron removed from the 3s orbital Ne 1s 2 2s 2 2p 6 CHLORINE Cl1s 2 2s 2 2p 6 3s 2 3p 5 Cl - 1s 2 2s 2 2p 6 3s 2 3p 6 1 electron added to the 3p orbital Ar 1s 2 2s 2 2p 6 3s 2 3p 6

The electron configurations of different ions:

ELECTRON CONFIGURATION OF IONS

Solutions 25.

Solutions 26.

Solutions 27. (a) Full electron configuration for Ne: 1s 2 2s 2 2p 6 (b) Fl - 1s 2 2s 2 2p 6 Na + 1s 2 2s 2 2p 6

Position of element is based on the occupied sub level of the highest energy in a ground state atom. You can use the periodic table to deduce electronic configuration: Cs (Group 1, period 6)  [Xe] 6s 1 I (Group 17, period 5)  [Kr] 5s 2 4d 10 5p 5 (should be written: 4d 10 5s 2 5p 5 )  this will give the correct valency of 7)

Solutions 28.

Solutions 29.

Solutions 30. Look at the periodic table: Tin (Sn) is [Kr] 4d 10 5s 2 5p 2  so it has a total number of 5 p orbitals. 31. Look at the periodic table: Barium (Ba) is [Xe] 6s2  so has only occupied 3d and 4d orbitals  10 in each = 2 x 10 = 20 electrons in the d orbitals of Barium. 32. Cd: [Kr] 5s 2 4d 10 or [Kr] 4d 10 5s 2 (Write like this because positive ions will take from the 5s shell first) Cd2+: [Kr] 4d 10

Ion energy level diagram Draw the energy level diagram for Cu + Draw the energy level diagram for Cl - Remember the following the rules. Electrons are removed first from the occupied orbital of highest energy. ACTIVITY