Lecture Notes: Periodic Properties of Elements

Introduction

• Topic: Periodic properties of elements
• Personal story shared about feeling old
• Fun fact: Silicon gas is toxic (learned from Dan Brown's Digital Fortress)
• Humor: "Chemistry Cat of the Day"
  • Joke: Two men walk into a bar, one orders H2O, the other H2O2, the latter dies

Lecture Goals

• Cover sections 4-6 of Chapter 7
• Outcomes expected for students:
  1. Understand isoelectronic series
  2. Derive electron configurations for ions
  3. Know periodic trends in ionization energies
  4. Understand periodic trends in electron affinities
  5. Familiarize with characteristics of metals, non-metals, metalloids
• Note: Sections 7 and 8 will be skipped

Isoelectronic Series

• Definition: Ions with the same number of electrons
• Example: Ions with same electron configuration as neon
• Example problem discussed: Comparing fluoride and sodium cation size
• Encouragement to solve problems independently, additional video link provided

Electron Configurations of Ions

• Deriving configurations for ions similar to neutral atoms
• Example: Sodium cation
  • Neutral sodium configuration derived first
  • Remove electrons from outermost orbital to form cation
  • Sodium plus ion is isoelectronic with neon
• For negatively charged ions, add electrons to outermost orbitals
• Example problems provided, additional video link for answers

Ionization Energies

• Energy required to remove an electron from an atom
• Definitions:
  • First ionization energy: Energy to remove first electron
  • Second ionization energy: Energy to remove second electron
• Trend: Higher energy orbitals have electrons easier to remove
• Example: Sodium ionization energies
  • 496 kJ/mol to remove first electron
  • Much higher energy for second electron
• Trend across periodic table:
  • Ionization energy generally increases across a row
  • Exceptions noted (e.g., aluminum)
  • Increase due to additional protons attracting electrons more tightly
• Thought questions provided for self-study

Problem Set Questions

• Comparison of ionization energies between elements (e.g., lithium vs sodium)
• Relationship between atom size and ionization energy
• Prediction tasks based on periodic table positions
• Encouragement to attempt questions independently

Conclusion

• Teaser for next video on electron affinities
• Encouragement to have a good day

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These notes capture the key points from the lecture on periodic properties, focusing on the isoelectronic series, electron configurations, and ionization energies. Students are encouraged to engage with problem sets and additional resources for deeper understanding.