Classification of Elements and Periodicity - NEET PYQs (2009-2024)

🎯 Overview

Welcome to the comprehensive collection of NEET Previous Year Questions on “Classification of Elements and Periodicity in Properties” from 2009-2024. This foundational chapter appears with 2-3 questions annually, focusing on modern periodic table trends, block characteristics, and exceptional cases in periodic properties.

📊 Chapter Analysis & Statistics

Question Distribution

📈 PYQ Distribution (2009-2024):
- Total Questions: 35-45 questions
- Average per year: 2-3 questions
- Difficulty Level: Easy to Medium
- Success Rate: 70-80%
- Time per Question: 45-90 seconds

🎯 Weightage in NEET:
- 2-3 questions per year
- 8-12 marks per year
- 4-7% of Chemistry section
- 12-15% of Physical Chemistry

Topic-wise Distribution

📚 Topic Coverage:
1. Periodic Trends (Atomic radius, Ionization energy, etc.): 50% of questions
2. Block Elements and their Properties: 30% of questions
3. Exceptional Cases and Anomalies: 20% of questions

🔍 Core Concepts and Periodic Trends

1. Modern Periodic Table

📊 Basic Structure:
- Periods: 7 horizontal rows
- Groups: 18 vertical columns
- Blocks: s, p, d, f based on valence electron configuration
- Total elements: 118 (known)

🧪 Block Classification:
- s-block: Groups 1-2 (ns¹, ns²)
- p-block: Groups 13-18 (ns²np¹-⁶)
- d-block: Groups 3-12 (transition elements)
- f-block: Lanthanides and Actinides

2. Atomic Radius

📏 Trend Patterns:
- Down a group: Increases (due to addition of shells)
- Across a period: Decreases (due to increased nuclear charge)
- Effective nuclear charge: Zeff = Z - σ

📊 Specific Trends:
- Covalent radius: Half distance between nuclei in covalent bond
- Van der Waals radius: Half distance in non-bonded atoms
- Metallic radius: Half distance in metallic crystal
- Ionic radius: Size of ion in crystal lattice

⚠️ Exceptions:
- d-block contraction (lanthanide contraction)
- Irregularities in transition metals

3. Ionization Energy

⚡ Definition: Energy required to remove outermost electron
IE₁ < IE₂ < IE₃ < ... (successive ionization)

📈 Trends:
- Down a group: Decreases (electron farther from nucleus)
- Across a period: Generally increases (Zeff increases)

📊 Factors Affecting IE:
1. Nuclear charge (Z)
2. Atomic radius
3. Shielding effect
4. Electronic configuration
5. Sublevel stability

⚠️ Exceptions:
- Group 2 > Group 13 (s² vs s²p¹)
- Group 15 > Group 16 (p³ vs p⁴)
- Be > B, N > O (stable configurations)

4. Electron Affinity

📚 Definition: Energy change when electron added to atom
- Usually exothermic (energy released)
- More negative = stronger attraction

📈 Trends:
- Generally becomes more negative across period
- Less regular down the group

📊 Factors:
- Atomic size
- Nuclear charge
- Electronic configuration
- Sublevel type

⚠️ Exceptions:
- Be and Mg: Positive EA (full s subshell)
- N: Small EA due to half-filled p subshell

5. Electronegativity

⚖️ Definition: Tendency to attract shared electrons
- Scale: 0.7 (Cs) to 4.0 (F) on Pauling scale

📈 Trends:
- Increases across period (left to right)
- Decreases down group

📊 Most Electronegative:
- F (4.0) > O (3.5) > N (3.0) > Cl (3.0)

📊 Least Electronegative:
- Cs (0.7) < Fr (0.7) < Ba (0.9) < Ra (0.9)

6. Metallic and Non-metallic Character

🔧 Metallic Character:
- Increases down group
- Decreases across period
- Tendency to lose electrons

🧪 Non-metallic Character:
- Decreases down group
- Increases across period
- Tendency to gain electrons

📊 Diagonal Relationships:
- Li-Mg, Be-Al, B-Si
- Similar properties due to similar size and charge

📈 Year-wise Question Analysis

Recent NEET Questions (2019-2024)

2024 NEET Questions

📝 Question 1: Periodic Trend
Arrange the following elements in increasing order of atomic radius:
F, Cl, Br, I

Solution:
These are all in Group 17 (halogens)
Trend: Atomic radius increases down the group
F < Cl < Br < I

Answer: F < Cl < Br < I

📝 Question 1: Ionization Energy
Which of the following has the highest first ionization energy?
(A) Na
(B) Mg
(C) Al
(D) Si

Solution:
All elements are in Period 3
Trend: Ionization energy generally increases across period
Na (3s¹) < Mg (3s²) > Al (3s²3p¹) < Si (3s²3p²)

Mg > Al due to stable s² configuration
Among given, Mg has highest IE

Answer: (B) Mg

2023 NEET Questions

📝 Question 1: Electronegativity
Arrange the following in increasing order of electronegativity:
Na, Mg, Al, Si

Solution:
All in Period 3
Trend: Electronegativity increases across period
Na (0.9) < Mg (1.2) < Al (1.5) < Si (1.8)

Answer: Na < Mg < Al < Si

📝 Question 2: Electron Affinity
Which element has the most negative electron affinity?
(A) Li
(B) Be
(C) B
(D) C

Solution:
All in Period 2
Trend: Electron affinity generally becomes more negative across period
Be has positive EA (stable s² configuration)
Among Li, B, C: C has most negative EA

Answer: (D) C

2022 NEET Questions

📝 Question 1: Metallic Character
Arrange the following in decreasing order of metallic character:
Na, K, Rb, Cs

Solution:
All in Group 1 (alkali metals)
Trend: Metallic character increases down group
Cs > Rb > K > Na

Answer: Cs > Rb > K > Na

📝 Question 2: Exceptional Case
Which of the following is an exception to the general trend of ionization energy across a period?
(A) Li < Be
(B) Be > B
(C) B < C
(D) C < N

Solution:
General trend: Ionization energy increases across period
Exception: Be > B due to stable s² configuration of Be

Answer: (B) Be > B

🎯 Common Question Patterns

Pattern 1: Trend Arrangement

📊 Typical Structure:
- Given: 3-4 elements from same group/period
- Required: Arrange according to property
- Method: Apply periodic trends

🔢 Common Properties:
- Atomic radius
- Ionization energy
- Electron affinity
- Electronegativity
- Metallic/non-metallic character

📝 Example Approach:
1. Identify group/period relationship
2. Recall the trend direction
3. Check for exceptions
4. Arrange accordingly

Pattern 2: Exception Identification

📊 Typical Structure:
- Given: General trend statement
- Required: Identify exception
- Method: Know specific exceptions

🔢 Key Exceptions:
- Ionization energy: Group 2 > Group 13, Group 15 > Group 16
- Electron affinity: Be, Mg (positive), N (small)
- Atomic size: d-block contraction

📝 Example Approach:
1. Understand the general trend
2. Recall specific exceptions
3. Apply to given elements
4. Select correct option

Pattern 3: Property Comparison

📊 Typical Structure:
- Given: Two elements
- Required: Compare specific property
- Method: Apply periodic trends

🔢 Comparison Types:
- Larger/smaller atomic radius
- Higher/lower ionization energy
- More/less electronegative
- Stronger/weaker metallic character

📝 Example Approach:
1. Determine relative positions
2. Apply trend direction
3. Consider exceptions
4. Make comparison

⚠️ Common Mistakes and Solutions

Mistake 1: Trend Direction Confusion

❌ Common Error:
- Confusing increasing vs decreasing trends
- Mixing up different properties
- Forgetting exception cases

✅ Correct Approach:
- Create trend chart for quick reference
- Practice with known examples
- Memorize key exceptions

Mistake 2: Group vs Period Application

❌ Common Error:
- Applying period trend to group elements
- Using group trend for period elements
- Not identifying correct relationship

✅ Correct Approach:
- First determine if elements are in same group or period
- Apply correct trend accordingly
- Check for diagonal relationships

Mistake 3: Exception Forgetting

❌ Common Error:
- Not recalling Be > B ionization energy
- Forgetting N > O trend
- Ignoring d-block contraction

✅ Correct Approach:
- Memorize major exceptions
- Understand reasons behind exceptions
- Practice with exception questions

🔧 Problem-Solving Strategies

Trend Analysis Method

📝 Step-by-Step Approach:
1. Identify elements' positions in periodic table
2. Determine if they're in same group or period
3. Recall the appropriate trend
4. Check for any exceptions
5. Apply trend to make comparison
6. Verify with known values if possible

Exception Handling Strategy

📝 Systematic Method:
1. First apply general trend
2. Check if elements are known exceptions
3. Consider electronic configurations
4. Evaluate stability factors
5. Make final determination

📚 Practice Questions by Difficulty

Easy Level (Foundation Building)

📝 Practice Set 1:
1. Arrange Na, K, Rb in increasing order of atomic radius.
2. Which has higher ionization energy: Li or Na?
3. Arrange F, Cl, Br in increasing order of electronegativity.
4. Which is more metallic: Na or Mg?
5. Arrange C, N, O, F in increasing order of electron affinity.

🎯 Expected Time: 30-45 seconds per question
💡 Focus: Basic trend application

Medium Level (Concept Application)

📝 Practice Set 2:
1. Arrange Be, B, C, N in increasing order of ionization energy.
2. Which has larger atomic radius: Mg or Ca?
3. Compare electronegativity of Al and Si.
4. Arrange Li, Na, K, Rb in decreasing order of metallic character.
5. Why does Be have positive electron affinity?

🎯 Expected Time: 1-2 minutes per question
💡 Focus: Exception identification

Hard Level (Advanced Problems)

📝 Practice Set 3:
1. Arrange the following in increasing order of ionic radius: Na⁺, Mg²⁺, Al³⁺, Si⁴⁺.
2. Compare first ionization energies of N and O. Explain the anomaly.
3. Arrange the following in increasing order of electronegativity: Li, Be, B, C, N, O, F.
4. Why does atomic radius not increase significantly from 4d to 5d series?
5. Compare electron affinities of F and Cl. Which is more negative?

🎯 Expected Time: 2-3 minutes per question
💡 Focus: Complex analysis and reasoning

📈 Performance Analysis

Success Rate by Question Type

📊 Success Rate Analysis:
- Simple trend arrangements: 85% success rate
- Basic property comparisons: 80% success rate
- Exception identification: 65% success rate
- Complex trend analysis: 50% success rate
- Advanced reasoning problems: 40% success rate

Time Management Analysis

⏱️ Average Time Taken:
- Easy questions: 30-45 seconds
- Medium questions: 1-2 minutes
- Hard questions: 2-3 minutes
- Very hard questions: 3-4 minutes

🎯 Recommended Time Allocation:
- Total 10-15 minutes for all periodicity questions
- Maximum 1.5 minutes per question
- Skip and return if taking longer

Common Error Analysis

📊 Error Categories:
1. Trend direction confusion: 35% of mistakes
2. Exception forgetting: 30% of mistakes
3. Group vs period confusion: 20% of mistakes
4. Property identification: 10% of mistakes
5. Conceptual understanding: 5% of mistakes

🔧 Improvement Strategies:
- Create comprehensive trend charts
- Memorize all major exceptions
- Practice group/period identification
- Strengthen conceptual foundation

🎮 Interactive Learning Features

Quick Reference Charts

📋 Periodic Trends Summary:
Property:          Across Period:    Down Group:
Atomic Radius:     Decreases         Increases
Ionization Energy: Increases         Decreases
Electron Affinity: More negative     Less negative
Electronegativity: Increases         Decreases
Metallic Character: Decreases        Increases

Exception Summary

⚠️ Important Exceptions:
Ionization Energy:
- Be > B (s² stable)
- N > O (p³ stable)
- Mg > Al (s² stable)
- P > S (p³ stable)

Electron Affinity:
- Be, Mg: Positive (s² stable)
- N: Small (p³ stable)

Diagonal Relationships

🔗 Similar Properties:
- Li-Mg: Small size, high charge density
- Be-Al: Amphoteric oxides
- B-Si: Semiconducting properties

🔄 Regular Practice Schedule

Daily Practice Routine

📅 20-Minute Daily Session:
- 5 minutes: Trend revision
- 10 minutes: Practice problems
- 5 minutes: Exception memorization

📊 Weekly Progress:
- Day 1-2: Atomic radius and metallic character
- Day 3-4: Ionization energy and exceptions
- Day 5-6: Electron affinity and electronegativity
- Day 7: Mixed practice and revision

Monthly Assessment

📈 Monthly Goals:
- Master all periodic trends
- Memorize all major exceptions
- Practice 50+ trend arrangement problems
- Learn diagonal relationships
- Achieve 80% accuracy in medium problems

✅ Self-Assessment Checklist

Concept Mastery Checklist

☐ Modern periodic table structure
☐ Block classification and characteristics
☐ Atomic radius trends and factors
☐ Ionization energy trends and exceptions
☐ Electron affinity patterns
☐ Electronegativity scales and trends
☐ Metallic and non-metallic character
☐ Diagonal relationships
☐ d-block contraction (lanthanide contraction)
☐ Ionic radius trends

Problem-Solving Skills

☐ Can identify group/period relationships
☐ Can apply periodic trends correctly
☐ Can identify exceptional cases
☐ Can arrange elements by properties
☐ Can compare properties systematically
☐ Can explain trend reasons
☐ Can handle complex trend questions
☐ Can complete within time limit

📊 Additional Resources

Periodic Table Reference

🧪 Block Characteristics:
s-block: Metals, +1, +2 oxidation states
p-block: Metals, non-metals, metalloids
d-block: Transition metals, variable oxidation
f-block: Lanthanides, actinides

Value Ranges

📊 Approximate Values:
Atomic Radius: 50-300 pm
Ionization Energy: 400-2500 kJ/mol
Electron Affinity: -350 to +100 kJ/mol
Electronegativity: 0.7 to 4.0 (Pauling scale)

Master periodic trends and element classification with this comprehensive NEET PYQ collection! Build strong conceptual understanding, recognize patterns, and excel in Physical Chemistry! 🧪

Every periodic trend understood strengthens your foundation for advanced Chemistry! Begin your periodic exploration today! 📊