3
Question Question 3
Differentiate between:
(a) Reactants and products
(b) Chemical reaction and chemical equation
(c) A balanced and a skeletal chemical equation
(a) Difference between reactants and products :
| Reactants | Products |
|---|---|
| The substances that undergo chemical change are called reactants. | The new substances formed as a result of reaction are called products. |
| Reactants are written on the left hand side of the equation. | Products are written on the right hand side of the equation. |
| In equation C + O2 ⟶ CO2, C and O2 are reactants. | In equation C + O2 ⟶ CO2, CO2 is product. |
(b) Difference between chemical reaction and chemical equation :
| Chemical reaction | Chemical equation |
|---|---|
| Any chemical change in matter which involves its transformation into one or more new substances is called a chemical reaction. | A chemical reaction can be represented with the help of symbols or the formulae of the elements and the compounds taking part in the reaction in the form of a chemical equation. |
| Example of chemical reaction is burning of candle. | Example — 2H2 + O2 ⟶ 2H2O |
(c) Difference between a balanced and a skeletal chemical equation :
| Balanced chemical equation | Skeletal chemical equation |
|---|---|
| In balanced chemical equation the total number of atoms on the reactant side as well as the product side are equal. | In skeletal chemical equation the total number of atoms on the reactant side and product side are not equal. |
| Example: Zn + H2SO4 ⟶ ZnSO4 + H2 | Example: H2 + O2 ⟶ H2O |
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