Periodicity Class 11: All Formulas & Formula Sheet with Free PDF Download (Chemistry, JEE & NEET)
Periodicity Class 11 Formula Sheet — Competishun
Periodicity Class 11: All Formulas & Formula Sheet with Free PDF Download (Chemistry, JEE & NEET)
Periodicity Class 11 is the foundation of inorganic chemistry for JEE and NEET.
Every year, 3-4 questions from this chapter appear in these exams.
These questions test your understanding of the modern periodic law, blocks, configuration, and periodic trends.
A clear grasp of Periodicity Class 11 also helps you predict properties of elements and their compounds.
This page gives you a complete Periodicity Class 11 formula sheet.
It covers the development of the periodic table, modern periodic law, blocks and configuration to position, IUPAC naming for elements Z>100, and periodic trends.
Download the free PDF below and keep it handy for quick revision before your JEE Main, JEE Advanced, or NEET exam.
Download the Periodicity Class 11 Formula Sheet PDF
Get all Periodicity Class 11 concepts in one clean PDF, free. Perfect for JEE & NEET revision.
Download Free PDFWhat is Periodicity Class 11 in Chemistry?
Periodicity Class 11 is the study of repeating trends in properties of elements.
These properties repeat when elements are arranged in increasing order of atomic number.
The modern periodic law states that properties are periodic functions of atomic number.
This is the foundation chapter for inorganic chemistry in Class 11.
Development of the Periodic Table for Periodicity Class 11
The periodic table evolved over time as scientists discovered more elements.
Understanding this history helps you appreciate why the modern periodic law is so powerful.
| Scientist | Year | Contribution | Limitation |
|---|---|---|---|
| Döbereiner | 1829 | Triads — atomic mass of middle element is mean of other two | Only a few triads exist |
| Newlands | 1865 | Law of Octaves — every 8th element repeats properties | Valid only up to Ca (Z=20) |
| L. Meyer | 1869 | Atomic-volume curve — peaks are alkali metals | Plotted vs atomic mass |
| Mendeleev | 1869 | Periodic Law (mass) — left gaps, predicted Sc, Ga, Ge | Anomalous pairs; H & isotopes |
| Moseley | 1913 | X-ray spectra — √ν = a(Z − b), Z is fundamental | Corrected anomalous pairs |
| Moseley's work proved that atomic number (Z) is the fundamental property for Periodicity Class 11. | |||
Modern Periodic Law for Periodicity Class 11
The modern periodic law states that the physical and chemical properties of elements are periodic functions of their atomic number.
This is because the outer electronic configuration repeats periodically.
Anomalous pairs (mass order broken): Ar before K, Co before Ni, Te before I, Th before Pa. All four fix themselves when ordered by Z.
The Modern Periodic Table for Periodicity Class 11
7 periods · 18 groups · 4 blocks (s, p, d, f).
Each element's position is determined by its electronic configuration.
| Block | Valence Configuration | Groups | Group Number |
|---|---|---|---|
| s-block | ns1-2 | 1, 2 | no. of s e− |
| p-block | ns2np1-6 | 13-18 | 10 + (s + p) e− |
| d-block | (n−1)d1-10ns0-2 | 3-12 | (n−1)d + ns e− |
| f-block | (n−2)f1-14(n−1)d0-1ns2 | 3 | always 3 |
| Period number = n (principal quantum number of valence shell). This is essential for Periodicity Class 11. | |||
Configuration to Position for Periodicity Class 11
The position of an element in the periodic table can be found from its electronic configuration.
This is one of the most important skills in Periodicity Class 11.
| Element (Z) | Configuration | Block | Period | Group |
|---|---|---|---|---|
| 15 (P) | [Ne]3s²3p³ | p | 3 | 15 |
| 25 (Mn) | [Ar]3d⁵4s² | d | 4 | 7 |
| 33 (As) | [Ar]3d¹⁰4s²4p³ | p | 4 | 15 |
| 64 (Gd) | [Xe]4f⁷5d¹6s² | f | 6 | 3 |
| Always remove ns electrons first during ionisation. This is a key rule for Periodicity Class 11. | ||||
Anomalous Configurations in Periodicity Class 11
Exactly half-filled (d⁵, f⁷) and fully filled (d¹⁰, f¹⁴) sets are extra stable.
This is due to symmetrical charge distribution and larger exchange energy.
These anomalous configurations are frequently tested in Periodicity Class 11 exams.
| Element | Expected | Actual |
|---|---|---|
| Cr (24) | 3d⁴4s² | [Ar] 3d⁵4s¹ |
| Cu (29) | 3d⁹4s² | [Ar] 3d¹⁰4s¹ |
| Mo (42) | 4d⁴5s² | [Kr] 4d⁵5s¹ |
| Ag (47) | 4d⁹5s² | [Kr] 4d¹⁰5s¹ |
| Pd (46) | 4d⁸5s² | [Kr] 4d¹⁰5s⁰ |
| Pt (78) | 5d⁸6s² | [Xe] 4f¹⁴5d⁹6s¹ |
| Au (79) | 5d⁹6s² | [Xe] 4f¹⁴5d¹⁰6s¹ |
| Pd is the only element with no outer s electron. Memorise these for Periodicity Class 11. | ||
IUPAC Naming for Periodicity Class 11 (Z > 100)
Pure decoding — no chemistry involved.
These names are systematic and temporary until a permanent name is approved.
This topic is often asked in Periodicity Class 11 exams.
| Digit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
|---|---|---|---|---|---|---|---|---|---|---|
| Root | nil | un | bi | tri | quad | pent | hex | sept | oct | enn |
| Letter | n | u | b | t | q | p | h | s | o | e |
| Rules: String roots in order of digits of Z, add -ium. Drop final 'i' of bi/tri before -ium. Drop 'n' of enn before nil. | ||||||||||
Important Periodic Trends for Periodicity Class 11
These trends are the most frequently tested in JEE and NEET.
Memorise the direction and reason for each trend in Periodicity Class 11.
| Property | Across Period (→) | Down Group (↓) |
|---|---|---|
| Atomic radius | Decreases (↑ effective nuclear charge) | Increases (↑ shells) |
| Ionisation enthalpy | Increases (↑ nuclear charge) | Decreases (↑ distance from nucleus) |
| Electron gain enthalpy | Becomes more negative | Becomes less negative |
| Electronegativity | Increases | Decreases |
| Metallic character | Decreases | Increases |
| Non-metallic character | Increases | Decreases |
| Exceptions exist (e.g., noble gases have high ionisation enthalpy, electron gain enthalpy is positive). | ||
All Periodicity Class 11 Concepts at a Glance
Here is a quick reference table of all the key concepts from Periodicity Class 11.
| Concept | Key Point |
|---|---|
| Modern Periodic Law | Properties are periodic function of atomic number (Z) |
| s-block | Groups 1-2, valence ns¹⁻² |
| p-block | Groups 13-18, valence ns²np¹⁻⁶ |
| d-block | Groups 3-12, valence (n−1)d¹⁻¹⁰ns⁰⁻² |
| f-block | Lanthanoids (Ce→Lu) and Actinoids (Th→Lr) |
| Anomalous configurations | Cr, Cu, Mo, Ag, Pd, Pt, Au — due to half/full filled stability |
| IUPAC naming | Roots: nil, un, bi, tri, quad, pent, hex, sept, oct, enn |
| Periodic trends | Atomic radius ↓ across, ↑ down; IE ↑ across, ↓ down |
| Memorise these concepts — they are the foundation of inorganic chemistry in Periodicity Class 11. | |
Common Mistakes in Periodicity Class 11
- Confusing atomic number and atomic mass: Modern periodic law is based on Z (atomic number), not mass. This is the most common error in Periodicity Class 11.
- Forgetting anomalous configurations: Cr is 3d⁵4s¹, not 3d⁴4s². Cu is 3d¹⁰4s¹, not 3d⁹4s². These are frequently tested in Periodicity Class 11.
- Getting group number wrong for d-block: Group number = (n−1)d + ns electrons. For Fe (3d⁶4s²), group = 6+2 = 8.
- Misapplying IUPAC naming rules: Drop 'i' from bi/tri before -ium. Drop 'n' from enn before nil.
- Confusing trends: Atomic radius decreases across a period but increases down a group. Ionisation enthalpy is the opposite.
Why Periodicity Class 11 Matters for JEE and NEET
- High weightage: Periodicity Class 11 appears in 3-4 questions in every JEE Main, JEE Advanced, and NEET chemistry paper.
- Foundation for inorganic chemistry: Understanding Periodicity Class 11 helps you predict properties of elements and their compounds.
- Direct scoring: Many questions are direct — block, group, period, configuration, or IUPAC naming in Periodicity Class 11.
- Connects to other topics: Periodicity Class 11 links to chemical bonding, coordination compounds, and p-block chemistry.
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Frequently Asked Questions — Periodicity Class 11
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