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Question We get the following information from the given chemical equation:
- Hydrogen and Chlorine are reactants.
- The reaction is irreversible.
- The product formed is hydrochloric acid.
- The equation is balanced i.e. number of atoms of each element on reactants and products sides are equal.
ICSE Class VII Chemistry Chapter 4 12 Marks
Language of Chemistry — Quick Study Guide
Chemical symbols, formulae, and equations are the language chemists use to describe substances and reactions.
Key Concepts
- Chemical symbol: Shorthand for an element (first letter capital, second lowercase)
- Chemical formula: Shows types and numbers of atoms in a molecule
- Cross-multiplication: Write symbols → valencies → cross → simplify
- Balanced equation: Same number of each atom on both sides
- Combination reaction: A + B → AB
- Decomposition reaction: AB → A + B
Latin-Origin Symbols to Memorise
Na (Sodium), Fe (Iron), Au (Gold), Ag (Silver), K (Potassium), Cu (Copper), Hg (Mercury), Pb (Lead), Sn (Tin)
Exam Tips
- Never change subscripts when balancing — only change coefficients
- Use brackets for polyatomic ions when subscript > 1
- Practice writing formulae using cross-multiplication daily
- CO ≠ Co (carbon monoxide vs cobalt)
Bright Tutorials | ICSE Class VII Chemistry | Chapter 4: Language of Chemistry | Contact: 9403781999