AP Chemistry orbital diagram review and quiz

⚛️ Quick Study Guide

• 🧪 Orbitals: Regions of space where electrons are likely to be found. Remember s, p, d, and f orbitals have different shapes.
• 🔢 Principal Quantum Number (n): Indicates the energy level of an electron (n = 1, 2, 3...). Higher n means higher energy.
• 🧭 Aufbau Principle: Electrons fill orbitals starting with the lowest energy levels first (1s, 2s, 2p, 3s, 3p, 4s, 3d...).
• ⬆️ Hund's Rule: Within a subshell, electrons individually occupy each orbital before any orbital is doubly occupied. All singly occupied orbitals have the same spin (maximize the total spin).
• ↔️ Pauli Exclusion Principle: No two electrons in an atom can have the same set of four quantum numbers. This means each orbital can hold a maximum of two electrons with opposite spins.
• 💡 Orbital Filling Order Exception: Chromium (Cr) and Copper (Cu) are exceptions. They borrow an electron from the 4s orbital to achieve a more stable half-filled or fully-filled d subshell.
• 📐 Example Configuration: $Cr: [Ar] 4s^1 3d^5$ (instead of $[Ar] 4s^2 3d^4$)

🧪 Practice Quiz

1. Which of the following represents the correct electron configuration for the ground state of nitrogen (N)?
   1. $1s^2 2s^2 2p^2$
   2. $1s^2 2s^2 2p^3$
   3. $1s^2 2s^2 2p^4$
   4. $1s^2 2s^3 2p^2$
2. What is the maximum number of electrons that can occupy a p subshell?
   1. 2
   2. 4
   3. 6
   4. 8
3. According to Hund's rule, which electron configuration is most stable for a $d^4$ configuration?
   1. $\uparrow\downarrow$ $\uparrow\downarrow$ __ __ __ __
   2. $\uparrow\downarrow$ $\uparrow$ $\uparrow$ $\uparrow$ $\uparrow$
   3. $\uparrow$ $\uparrow$ $\uparrow$ $\uparrow$ __
   4. $\uparrow\downarrow$ $\uparrow\downarrow$ $\uparrow\downarrow$ $\uparrow\downarrow$ $\uparrow\downarrow$
4. Which element has the electron configuration $[Ar] 4s^2 3d^4$?
   1. Cr
   2. Mn
   3. V
   4. Ti
5. Which of the following violates the Pauli Exclusion Principle?
   1. $\uparrow\downarrow$
   2. $\uparrow$ __
   3. $\uparrow\uparrow$
   4. $\downarrow$ __
6. What is the correct electron configuration for Chromium (Cr)?
   1. $[Ar] 4s^2 3d^4$
   2. $[Ar] 4s^1 3d^5$
   3. $[Ar] 4s^2 3d^5$
   4. $[Ar] 4s^1 3d^4$
7. Which of the following orbitals is filled first?
   1. 3d
   2. 4s
   3. 4p
   4. 3p