Electron Configuration – AP Chemistry | ShowMeClass

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Electron Configuration

AP Chemistry · Unit 1: Atomic Structure

Learning Objectives

Write electron configurations using spdf notation

Apply Aufbau, Pauli exclusion, Hund's rules

Identify valence electrons and core electrons

Relate config to periodic table position

Three Rules

Aufbau: Fill lowest energy orbitals first

Pauli Exclusion: Max 2e⁻ per orbital, opposite spins

Hund's Rule: Fill degenerate orbitals singly first

Aufbau Order

        1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d → 5p → 6s → 4f → 5d → 6p
      

Electron ConfigAufbauAP Chemistry

Select Element (Z=1–36)

Element—

Z (protons)—

Electrons—

Valence e⁻—

Period / Group—

Configuration:

📝 Quick Quiz▼

1. The electron configuration of Na (Z=11) is:

1s²2s²2p⁶3s² 1s²2s²2p⁶3s¹ 1s²2s²2p⁵3s² 1s²2s²2p⁴3s²3p¹

2. How many valence electrons does Cl (Z=17) have?

1 5 7 17

3. Which rule states that electrons fill degenerate orbitals singly before pairing?

Aufbau principle Pauli exclusion Hund's rule Heisenberg principle