Chemical Symbols, Formulae and Naming Compounds

Grade 10 · Chemistry

Semester 1 | Period 1 | Week 3

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Subject: Chemistry

Semester: 1

Period: 1

Week: 3

School Name:
Teacher’s Name:
Subject: Chemistry
Grade Level: Grade 10
Week & Period: Week 3, Period I
Date:
Topic: Chemical Symbols, Formulae and Naming Compounds
Sub-topics:
a) Origin of Symbols
b) Writing Formulae
c) Types of Formulae
d) Naming Compounds

 

Learning Objectives

By the end of the lesson, learners should be able to:

  • State the origin and meaning of chemical symbols
  • Write correct chemical symbols for common elements
  • Write molecular and empirical formulae for compounds
  • Differentiate types of formulae: empirical, molecular, structural
  • Apply basic rules in naming simple chemical compounds

 

Previous Knowledge

Learners have been introduced to atoms, elements, and basic atomic structure in Junior Secondary School Science. They know that each element has a unique symbol and that substances can be combined.

 

Instructional Materials

  • Periodic table
  • Flashcards with chemical symbols
  • Chart showing types of formulae
  • Printed samples of named compounds and their formulas
  • Marker, whiteboard, worksheets

 

Anticipation (Warm-Up) – 5 minutes

Ask:

  • “What does H₂O stand for?”
  • “Why do some elements have symbols that don’t match their English names?”
    (e.g., Na for sodium, Fe for iron)

Lead into: Symbols are based on Latin names, and writing formulas follows strict scientific rules.

 

Building Knowledge (Main Lesson) – 25 minutes

  1. Origin of Symbols:
    • Derived from Latin names (e.g., Fe = ferrum, Na = natrium)
    • One- or two-letter symbols: First letter capitalized, second (if any) lowercase
  2. Writing Chemical Formulae:
    • Combine symbols with correct ratios (e.g., NaCl, H₂O, CO₂)
    • Show use of valency in determining formulae (e.g., Mg²⁺ + Cl⁻ → MgCl₂)
  3. Types of Formulae:
    • Empirical Formula: simplest whole-number ratio (e.g., CH₂O)
    • Molecular Formula: actual number of atoms (e.g., C₆H₁₂O₆)
    • Structural Formula: shows how atoms are bonded (use simple diagrams)
  4. Naming Compounds:
    • Metal + Non-metal = ionic name (e.g., sodium chloride)
    • Use prefixes for covalent compounds (e.g., CO₂ = carbon dioxide)
    • Add rules for acids and bases (briefly introduce HCl, NaOH)

 

Learners’ Activities

  • Match element names to their correct symbols
  • Practice writing formulas based on given ions
  • Name compounds from given formulas and vice versa
  • Group activity: write 5 empirical and molecular formulae for assigned compounds

 

Consolidation (Review and Assessment) – 10 minutes

Oral Questions:

  • “What is the chemical symbol for potassium?”
  • “What does an empirical formula show?”
  • “How would you name the compound CO?”

Homework/Assignment:

  • List 10 elements and their symbols, including 3 whose symbols don’t match their English names
  • Write the formula for 5 compounds given their names and vice versa

 

Short Notes (For Learners)

Chemical symbols are letters used to represent elements. Some are from Latin. Chemical formulae show how elements combine to form compounds. Empirical formulas give the simplest ratio, while molecular formulas give the actual number of atoms. Naming compounds depends on whether they are ionic or covalent.

 

Expanded Notes/Instructions

Use flashcards and periodic tables to reinforce memorization of element symbols.
Demonstrate formula writing with familiar substances like table salt (NaCl) and sugar (C₆H₁₂O₆).
Let learners create their own compound flashcards as a memorization exercise.

 

Inclusive/Differentiation

  • Visual learners: color-coded periodic table and compound charts
  • Kinesthetic learners: card-matching games with symbols and names
  • Auditory learners: chants or mnemonics for memorizing tricky symbols
  • Struggling learners: scaffold formulas with step-by-step guides

 

Teacher’s Reflection (Post-lesson Questions)

  • Were learners able to understand the logic behind chemical symbols and their Latin origins?
  • Did they successfully write and interpret both empirical and molecular formulae?
  • Which formula type did learners struggle with most and why?
  • Was the naming of compounds clearly understood by the entire class?
  • Did I give enough relatable examples to help them connect new concepts with real life?
  • How well did learners perform during the matching and group activities?
  • What follow-up reinforcement might be needed before the next topic?