Atomic Structure & Periodic Table Basics

Grade 9 Science Understanding Atoms and Elements 60-minute lesson

Warm-Up Question

What subatomic particles make up an atom? Think about what you remember from previous science classes Write your answer in your notebook

Key Atomic Definitions

Atomic Number = Number of protons in nucleus In neutral atoms: Protons = Electrons Neutrons = Mass Number - Atomic Number Valence Electrons = Electrons in outermost shell

Reading the Periodic Table

Valence Electrons by Group

{"left":"Group 1: 1 valence electron\nGroup 2: 2 valence electrons\nGroup 13: 3 valence electrons\nGroup 14: 4 valence electrons","right":"Group 15: 5 valence electrons\nGroup 16: 6 valence electrons\nGroup 17: 7 valence electrons\nGroup 18: 8 valence electrons (except He: 2)"}

Build an Atom Model

Work in groups of 3-4 students Choose 2 elements: Lithium and Chlorine Use provided materials to build atomic models Show correct number of protons, neutrons, electrons Identify and highlight valence electrons

Lewis Dot Diagrams

Show valence electrons as dots around element symbol Place dots one at a time around four sides Pair up dots only after each side has one dot Example: Carbon has 4 valence electrons = 4 dots

Check Your Understanding

1. What is the atomic number of an element? 2. How do you find the number of neutrons? 3. How many valence electrons does a Group 2 element have? 4. Draw a Lewis dot diagram for Fluorine