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✅ TOPIC 1: ATOMIC STRUCTURE — FULL CONTENT

1.1 Meaning of an Atom

• An atom is the smallest particle of an element that can take part in a chemical reaction.

• All matter is made up of atoms.

1.2 Subatomic Particles

1.3 Atomic Number and Mass Number

• Atomic number (Z) = number of protons

• Mass number (A) = protons + neutrons

• Number of neutrons = A – Z

Example:

Carbon → Z = 6, A = 12
Neutrons = 12 – 6 = 6

1.4 Isotopes

• Isotopes are atoms of the same element with the same number of protons but different number of neutrons.
  Example: Carbon-12 and Carbon-14.

1.5 Electron Arrangement

Electrons fill shells in order:
1st shell → 2 electrons
2nd shell → 8 electrons
3rd shell → 8 electrons

Examples:

• Sodium (11): 2, 8, 1

• Oxygen (8): 2, 6

Activities

• Draw structure of atom of Magnesium

• Calculate neutron numbers for Na, K, Cl

Assessment Questions

1. Define an isotope.

2. What is the electron arrangement of sulfur?

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✅ TOPIC 2: THE PERIODIC TABLE — FULL CONTENT

2.1 Meaning of the Periodic Table

• A systematic arrangement of elements in order of increasing atomic number.

2.2 Groups and Periods

• Groups → vertical columns (1–18)

• Periods → horizontal rows (1–7)

2.3 Classification of Elements

• Metals: Good conductors, shiny, malleable

• Non-metals: Poor conductors, brittle

• Metalloids: Have both metal and non-metal properties (e.g., Si, B)

2.4 Trends in the Periodic Table

Across a period:

• Atomic size decreases

• Reactivity of metals decreases

• Reactivity of non-metals increases

Down a group:

• Atomic size increases

• Reactivity of metals increases (e.g., Group 1)

• Reactivity of non-metals decreases (e.g., Group 7)

2.5 Special Groups

• Group 1: Alkali metals (very reactive)

• Group 7: Halogens (reactive non-metals)

• Group 18: Noble gases (unreactive)

Activities

• Identify elements in Group 1 and their properties

• Classify given elements as metal or non-metal

Assessment Questions

1. Why are noble gases unreactive?

2. State two properties of Group 1 elements.

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✅ TOPIC 3: ACIDS AND BASES — FULL CONTENT

3.1 Meaning of Acids

• An acid is a substance that produces H⁺ ions in solution.

• Examples: Hydrochloric acid, sulfuric acid, lemon juice, vinegar.

Properties of acids

• Sour taste

• Turn blue litmus paper red

• pH < 7

• React with metals → hydrogen gas

• React with carbonates → CO₂ gas

3.2 Meaning of Bases

• A base produces OH⁻ ions in solution.

• Examples: Sodium hydroxide, potassium hydroxide, wood ash.

Properties of bases

• Bitter taste

• Turn red litmus blue

• pH > 7

• Feel slippery

• Neutralize acids

3.3 Indicators

• Show whether a substance is acidic or basic
  Examples:

• Litmus paper

• Methyl orange

• Phenolphthalein

• Natural indicators (hibiscus, red cabbage)

3.4 Reactions of Acids

1. Acid + Metal → Salt + Hydrogen
   Mg + HCl → MgCl₂ + H₂

2. Acid + Base → Salt + Water
   (Neutralization)

3. Acid + Carbonate → Salt + CO₂ + H₂O

Activities

• Test household substances using litmus (lemon, ash, soap)

• Prepare a natural indicator from hibiscus

Assessment Questions

1. Give two properties of bases.

2. What is produced when acids react with carbonates?

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✅ TOPIC 4: SALTS — FULL CONTENT

4.1 Meaning of a Salt

• A salt is a compound formed when hydrogen in an acid is replaced by a metal or ammonium ion.

Examples:

• NaCl (common salt)

• CuSO₄ (copper(II) sulfate)

• CaCO₃ (calcium carbonate)

4.2 Types of Salts

• Normal salts (all H replaced) → NaCl

• Acid salts (partly replaced H) → NaHSO₄

• Basic salts → Pb(OH)Cl

• Double salts → Alum

4.3 Preparation of Salts

1. Neutralization

Acid + Base → Salt + Water

2. Metal + Acid

Metal + Acid → Salt + Hydrogen

3. Carbonate + Acid

Carbonate + Acid → Salt + CO₂ + Water

4. Precipitation Method (for insoluble salts)

Mix two soluble salts → insoluble salt forms as a precipitate.

4.4 Solubility Rules (Simple)

• All nitrates are soluble

• All sodium, potassium, ammonium salts are soluble

• Most chlorides are soluble except silver and lead

• Most sulfates are soluble except barium, lead, calcium

Activities

• Prepare copper(II) sulfate crystals

• Classify salts as soluble or insoluble

Assessment Questions

1. Write the products of H₂SO₄ + Mg.

2. Name two soluble salts and two insoluble salts.