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The world’s no 1 online tuition center 🔬 Unit 04 – Periodic Table 📘 Topic: How to Find Group Number and Period Number Using Electronic Configuration ✅ Step-by-Step Guide 🔹 1. Write the Electronic Configuration of the Element Start by writing the electronic configuration of the element using the shell-wise distribution (K, L, M, N…) or subshell notation (1s², 2s²…). 🔹 2. Determine the Period Number 👉 The number of shells (energy levels) used in the configuration indicates the period number. 📌 Example: Na (Atomic No. 11) → 2, 8, 1 → 3rd shell used → Period = 3 🔹 3. Determine the Group Number (for s- and p-block elements) Group Number = Number of electrons in outermost shell (valence electrons) If it is a p-block element, add 10 to the number of valence electrons for group number. 📌 Examples: Mg (Atomic No. 12) → 2, 8, 2 → 2 valence electrons → Group = 2 Cl (Atomic No. 17) → 2, 8, 7 → p-block → 7 + 10 = Group 17 🔹 4. For d-block Elements (Transition Elements) Group number is generally the sum of electrons in the (n-1)d and ns orbitals. 📌 Example: Fe (Atomic No. 26) → 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶ → (3d⁶ + 4s² = 6 + 2) → Group 8, Period = 4 🧠 Pro Tips: Always count shells for period. For Group, check the block of the element: s-block: Group 1 or 2 p-block: Group 13–18 (valence e⁻ + 10) d-block: (n-1)d + ns electrons Exceptions may exist for some transition elements. 📚 Get Live Concept Clearing Classes with Expert Chemistry Teachers 🎥 One-on-One Zoom Sessions | 📖 Class Recordings | 💡 Topic-wise Practice 🔗 www.wisetutorhub.com 📞 Call/WhatsApp: 0313-7901158 | 0325-8155588. #Wisetutorhub #ChemistryMadeEasy #PeriodicTable #ElectronicConfiguration #GroupAndPeriod #OnlineTuition #FederalBoard #MatricChemistry #ScienceClass #LearnOnline