Hund's Rule

Summary

This script explains electron configuration using electron-box diagrams, starting with 1s orbital holding two electrons spinning in opposite directions. It follows the Aufbau principle, filling lower orbitals first, then discusses filling 2p orbitals using Hund's Rule, which states that degenerate orbitals are half-filled before being completely filled. The script emphasizes understanding electron configurations for different elements by following the periodic table or Aufbau diagram.

Takeaways

• 📚 Electron configuration involves filling electron orbitals according to specific rules.
• 🔵 Each s sublevel can hold two electrons with opposite spins (1s²).
• 📈 Following the Aufbau principle, fill lower energy orbitals before moving to higher ones.
• 🔵 The 2s sublevel also holds two electrons, one spinning up and one down.
• 🌀 In the 2p sublevel, there are five electrons to be distributed among three orbitals.
• 📝 Hund's Rule states that degenerate orbitals are half-filled before being completely filled.
• 🔵 Degenerate orbitals have the same energy, which applies to all three 2p orbitals.
• 📌 Half-fill the 2p orbitals first with electrons spinning up, then fill the rest spinning down.
• ⚠️ 1s and 2s orbitals are not degenerate; they have different energies due to different principal quantum numbers.
• 🔑 Understanding the periodic table and Aufbau diagram is crucial for determining electron configurations.
• 📝 Mastering electron configurations is essential for answering questions about various elements.

Q & A

What are electron-box diagrams?

Electron-box diagrams are visual representations where electrons within each orbital are physically shown.

How many electrons can an s orbital hold?

An s orbital can hold two electrons, which must spin in opposite directions.

What is the significance of the Aufbau principle in electron configuration?

The Aufbau principle requires filling the lower energy orbitals before moving on to the higher energy orbitals.

How many electrons are in the 2s orbital?

The 2s orbital also holds two electrons, one spinning up and the other spinning down.

How many electrons are typically in the 2p orbitals?

There are five electrons in the 2p orbitals, which are distributed among three p orbitals.

What is Hund's Rule and how does it apply to filling the 2p orbitals?

Hund's Rule states that degenerate orbitals should be half-filled before they are completely filled. This means that each of the three 2p orbitals gets one electron before any orbital gets a second electron.

What does the term 'degenerate' mean in the context of orbitals?

In the context of orbitals, 'degenerate' means that they have the same amount of energy.

Why are the 2p orbitals considered degenerate?

The 2p orbitals are considered degenerate because they are all 2 orbitals and all p orbitals, hence they have the same energy.

How does the energy of 1s and 2s orbitals differ?

The 1s and 2s orbitals have different energies because they have different principal quantum numbers (1 and 2 respectively).

What is the importance of knowing the periodic table version for electron configuration?

Knowing the periodic table version helps in understanding the order in which orbitals are filled, which is crucial for determining the electron configuration of elements.

Can you provide an example of how to fill the 2p orbitals following Hund's Rule?

Following Hund's Rule, you would first place one electron in each of the three 2p orbitals with their spins up. Then you would place the remaining two electrons in the orbitals with their spins down.