Overview of s-Block Elements

The s-Block elements occupy the leftmost part of the periodic table and include Group 1 (Alkali Metals) and Group 2 (Alkaline Earth Metals). Their valence electrons enter the s-orbital, making them highly reactive and electropositive. Due to their simple electronic configurations and predictable trends, s-Block elements form a crucial and scoring chapter in NEET Chemistry.

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Position and Electronic Configuration

• Alkali Metals (Group 1):
  General electronic configuration → ns¹

• Alkaline Earth Metals (Group 2):
  General electronic configuration → ns²

These configurations explain their strong tendency to lose electrons and form +1 and +2 oxidation states respectively.

Important Alkali Metals (Group 1)

Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs)

Key Characteristics:

• Soft metals with low melting points

• Highly reactive (reactivity increases down the group)

• Strong reducing agents

Important Formulas and Reactions of Alkali Metals

1. Reaction with Water

2Na + 2H₂O → 2NaOH + H₂ ↑

• Produces hydroxide and hydrogen gas

• Reaction becomes more violent down the group

2. Reaction with Oxygen

• Lithium forms oxide

  4Li + O₂ → 2Li₂O

• Sodium forms peroxide

  2Na + O₂ → Na₂O₂

• Potassium forms superoxide

  K + O₂ → KO₂

3. Reaction with Halogens

2Na + Cl₂ → 2NaCl

Important Compounds of Alkali Metals

Sodium Carbonate (Na₂CO₃) – Washing Soda

• Prepared by Solvay Process

• Used in glass, soap, and detergent industries

Sodium Bicarbonate (NaHCO₃) – Baking Soda

NaCl + NH₃ + H₂O + CO₂ → NaHCO₃ ↓ + NH₄Cl

Sodium Hydroxide (NaOH) – Caustic Soda

• Prepared by Electrolysis of Brine

2NaCl + 2H₂O → 2NaOH + H₂ + Cl₂

Important Alkaline Earth Metals (Group 2)

Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba)

Key Characteristics:

• Harder than alkali metals

• Higher melting points

• Less reactive but still electropositive

Important Formulas and Reactions of Alkaline Earth Metals

1. Reaction with Water

• Magnesium reacts slowly

Mg + 2H₂O → Mg(OH)₂ + H₂

• Calcium reacts readily

Ca + 2H₂O → Ca(OH)₂ + H₂

2. Reaction with Oxygen

2Mg + O₂ → 2MgO

Important Compounds of Alkaline Earth Metals

Calcium Oxide (CaO) – Quick Lime

CaCO₃ → CaO + CO₂

Calcium Hydroxide (Ca(OH)₂) – Slaked Lime

CaO + H₂O → Ca(OH)₂

Plaster of Paris (CaSO₄·½H₂O)

CaSO₄·2H₂O → CaSO₄·½H₂O + 1½H₂O

Anomalous Behavior of Lithium and Beryllium

• Lithium shows similarity with Magnesium (Diagonal Relationship)

• Beryllium shows covalent character due to high ionization energy

Examples:

• Li forms Li₃N

• BeCl₂ is covalent

Biological Importance

• Na⁺ and K⁺: Nerve impulse transmission

• Ca²⁺: Bone formation, muscle contraction

• Mg²⁺: Chlorophyll component

NEET Exam Tips for s-Block Elements

• Memorize reaction trends

• Focus on oxide formation

• Practice compound preparation reactions

• NCERT lines are extremely important

• Direct formula-based MCQs are common

Conclusion

s-Block Elements form a high-weightage and scoring chapter in NEET Chemistry. With well-defined trends, simple formulas, and predictable reactions, this topic becomes easy to master with regular revision. Understanding the chemistry of Alkali and Alkaline Earth Metals not only helps in NEET but also builds a strong foundation for advanced inorganic chemistry. These optimized notes by StudentBro are designed to help students revise efficiently and score confidently.