1.3.4 Sublevels & Orbitals - IB Chemistry

Main energy levels (n) are split into sub-levels (s, p, d, f). Each sub-level contains orbitals - regions of space where there is a high probability of finding an electron. Each individual orbital holds a maximum of 2 electrons.

s-orbitals

Spherical Shape

Found in all levels (n=1+).
1 orbital per sublevel.
Max 2 electrons.

p-orbitals

Dumbbell Shape

Found in n=2 onwards.
3 orbitals per sublevel (\(p_x, p_y, p_z\)).
Max 6 electrons.

Total Sublevel Capacities

                        s-sublevel2 e⁻
                    
                        p-sublevel6 e⁻
                    
                        d-sublevel10 e⁻
                    
                        f-sublevel14 e⁻

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Electrons fill the lowest available energy sublevels first. Notice that the 4s sublevel is slightly lower in energy than the 3d sublevel, so it fills first. When orbitals have the same energy (degenerate), they fill singly first (Hund's rule).

Sublevels & Orbitals

s-orbitals

p-orbitals

Total Sublevel Capacities

Orbital Energy Levels & Aufbau Principle

Orbital Energy Diagram (Example: Iron, Fe)

Exam Practice