E7 Valence Electrons and the Periodic Table

Aug 29, 2024

Mindmap

Lecture on Electrons and Valence Electrons

Overview

  • Focus on electrons in atoms
  • Understanding valence electrons
  • Using the periodic table to determine valence electrons
  • Drawing electron dot diagrams (Lewis diagrams)

Structure of the Atom

  • Nucleus: Contains protons and neutrons
  • Electrons:
    • Located in energy levels or shells around the nucleus
    • Energy levels can be thought of as "parking spots" or "theater seats"
    • Shells vary in distance from the nucleus
  • Energy Levels:
    • First energy level holds 2 electrons
    • Second energy level holds 8 electrons
    • Third energy level holds 8 electrons

Filling Electron Spaces

  • Use the periodic table to fill electrons
  • Focus on the first two and last six columns of the periodic table

Examples

  • Hydrogen:
    • 1 proton, 1 electron
    • Electron fills the first energy level
  • Lithium:
    • 3 protons, 3 electrons
    • First energy level is filled, 1 electron in the second energy level
  • Sodium:
    • 11 protons, 11 electrons
    • First two energy levels filled, starts third energy level

Valence Electrons

  • Electrons in the outermost energy level
  • Important for chemical properties
  • Pattern: Each element in the first column of the periodic table has one valence electron

Drawing Electron Dot Diagrams

  • Represent valence electrons as dots around the element symbol
  • Examples:
    • Lithium (Li): One dot above
    • Beryllium (Be): Two dots (one on top, one on bottom)

Patterns Across the Periodic Table

  • Second Column: Two valence electrons
  • Third Column: Three valence electrons
  • Fourth Column (Carbon, Silicon): Four valence electrons
  • Fifth Column (Nitrogen, Phosphorus): Five valence electrons
  • Sixth Column (Oxygen, Sulfur): Six valence electrons
  • Seventh Column (Fluorine, Chlorine): Seven valence electrons
  • Eighth Column (Helium, Neon, Argon): Full valence shells (Helium has 2, others have 8)

Summary

  • Valence electrons determine an element's chemical behavior
  • The position on the periodic table helps identify the number of valence electrons
  • Electron dot diagrams visually represent valence electrons

This lecture provides insight into understanding the arrangement and significance of electrons in atoms, particularly focusing on valence electrons and how to determine their number using the periodic table.