Module 08 · Electron Configuration Diagrams, Quantum Numbers, and Spin
Before you begin
Electron Configuration Diagrams, Quantum Numbers, and Spin
Read what this module is aiming for. Then open the instrument and work through it.
Learning intentions
Curricular competencies
Module 08
Act 1 of 5 · Shell limit
Electron Configuration Diagrams, Quantum Numbers, and Spin
Neon’s shell model sits here the way you’ve drawn it all unit.
Shell model
Two shells for neon — an inner pair and eight on the outer ring. That picture matched the old two-peak prediction.
Ne Shell model
Outer ring = one shell. Nowhere to mark the split.
s orbital
An s subshell is a single box. Two electrons can share that orbital.
1s · empty
Configuration —
AufbauHundPauliSpin
Electrons left
Looking back
Now that you can place valence electrons with orbital diagrams, those diagrams can explain some ionization-energy trends that core charge alone could not.
Why is there a disruption in the trend of ionization energy between Be and B, and between N and O?
First ionization energy · period 2 (MJ/mol)
In your notes, draw the orbital diagrams for Be, B, N, and O. Hypothesize what leads to each drop.
Model answer · compare with yours
Be → B
Beryllium’s valence electrons fill 2s. Boron’s next electron goes into 2p — a different subshell, held less tightly on average — so first ionization energy dips even though core charge rises.
N → O
Nitrogen’s 2p is half-full: three unpaired electrons. Oxygen’s fourth 2p electron must pair in a box. Electron repulsion makes that paired electron easier to remove, so IE₁ drops.
Unique seats
Every electron in an atom has its own address. Four quantum numbers name that seat.
O · 1s² 2s² 2p⁴
Model answer · compare with yours
ElementNe
Placed—
Z10
Continue when you’ve looked at the rings. The next click brings the instrument back.
What this was for
The intentions behind this module, and the competencies you just practised. Read each competency statement and decide honestly how well it fits you right now.