⚗️ Periodic Table Guide
Master the periodic table with exam-focused explanations and trends
118 Elements Periodic Trends Exam Tips
🔧 1. Organization of the Periodic Table
The periodic table organizes all 118 known elements by their atomic number and electron configuration. It is arranged in rows (periods) and columns (groups).
- Periods (Rows): 7 periods representing electron shells (1-7)
- Groups (Columns): 18 groups representing similar chemical properties
- Blocks: s, p, d, f blocks based on valence electron type
💡 Exam Tip: Remember that period number = number of electron shells. Group number
(in main groups) = number of valence electrons.
📊 2. Periodic Trends
Atomic Radius
- Increases: From right to left (across periods)
- Increases: From top to bottom (down groups)
- Reason: More electron shells = larger atoms
Ionization Energy
- Increases: From left to right (across periods)
- Decreases: From top to bottom (down groups)
- Highest: Noble gases (filled orbitals = most stable)
- Lowest: Alkali metals (easily lose one electron)
Electronegativity
- Increases: From left to right (across periods)
- Decreases: From top to bottom (down groups)
- Highest: Fluorine (F = 3.98)
- Lowest: Francium (Fr = 0.7)
Electron Affinity
- More negative: Nonmetals (gain electrons easily)
- Noble gases: Positive or near-zero (don't gain electrons)
- Halogens: Highest affinity (1 electron away from stable octet)
🧠 NEET Mnemonic: "Trends go LEFT for radius, RIGHT for ionization energy."
🎨 3. Groups and Element Categories
Group 1: Alkali Metals
- Valency: +1
- Highly reactive, soft metals
- React violently with water
- Examples: Li, Na, K, Rb, Cs, Fr
Group 2: Alkaline Earth Metals
- Valency: +2
- Reactive but less than alkali metals
- Examples: Be, Mg, Ca, Sr, Ba, Ra
Group 17: Halogens
- Valency: -1 (normally)
- Diatomic nonmetals (F₂, Cl₂, Br₂, I₂)
- Highly reactive, especially fluorine
- Form 1:1 salts with metals
Group 18: Noble Gases
- Valency: 0 (or variable for heavier ones)
- Inert, filled valence shells
- Examples: He, Ne, Ar, Kr, Xe, Rn
Transition Metals (d-block)
- Variable oxidation states (common: +2, +3)
- Form colored compounds
- Good catalysts
- Examples: Fe (+2, +3), Cu (+1, +2), Zn (+2)
🎯 JEE Focus: Master variable oxidation states and electron configuration of
transition metals. Remember: (n-1)d¹⁰ ns² for transitions.
⬜ 4. s, p, d, f Blocks
- s-block: Groups 1-2, 2 valence electrons max
- p-block: Groups 13-18, 6 valence electrons max
- d-block: Transition metals, 10 d-electron positions
- f-block: Lanthanides & Actinides, 14 f-electron positions
🎓 5. JEE Preparation Tips
- Memorize periodic trends: radius ↓→, IE ↓→, EN ↓→
- Focus on exceptions: Cr, Cu, Mn half-filled d-orbitals
- Understand redox potential and reactivity series
- Master coordination complex notation
- Study ionic charge determination from period/group
- Practice oxidation state calculations
🧪 6. NEET Preparation Tips
- Learn atomic structure: protons, neutrons, electrons
- Understand electron configuration and orbital diagrams
- Focus on commonly tested elements: C, N, O, H, S, P, Cl, Na, K, Ca, Fe
- Master valency for bonding predictions
- Learn biological importance: Ca (bones), Fe (hemoglobin), I (thyroid)
- Study common compounds: NaCl, CaCO₃, H₂SO₄
🚀 Explore Interactive Tools
Use our Periodic Table Explorer to search elements, apply filters, and see detailed properties with exam-focused insights.
Try our Chemistry Quiz to test your knowledge on periodic table concepts.