Unit 7 Overview
Engineering Chemistry Unit 7 focuses on Periodic Properties. These properties change regularly in the periodic table and depend on atomic number, electronic configuration, nuclear charge and shielding effect.
This unit is scoring for RGPV exams because definitions, trends and simple numerical problems based on effective nuclear charge are repeatedly asked.
Unit 7 Syllabus
- Periodic Properties
- Effective Nuclear Charge
- Shielding Effect
- Orbital Energies of s, p, d and f Orbitals
- Electronic Configuration
- Aufbau Principle
- Pauli Exclusion Principle
- Hund’s Rule
- Atomic Size
- Ionic Size
- Electron Affinity
- Electronegativity
- Polarizability
- Oxidation States
Most Important Topics for Exam
Effective Nuclear Charge
Most important definition and numerical topic.
Electronic Configuration
Repeated question based on Aufbau, Pauli and Hund’s rule.
Atomic & Ionic Size
Important periodic trend question.
Electron Affinity & Electronegativity
Frequently asked comparison and variation topic.
Short Notes for Quick Revision
1. Periodic Properties
Periodic properties are properties of elements which change regularly in the periodic table. These properties depend on atomic number, electronic configuration, nuclear charge and shielding effect.
2. Effective Nuclear Charge
Effective nuclear charge is the net positive charge experienced by the outermost electron after the shielding effect of inner electrons.
3. Shielding Effect
Shielding effect is the reduction in attraction between nucleus and outer electrons due to repulsion by inner electrons.
4. Orbital Energies
The energy order of orbitals is generally s < p < d < f. The s-orbital has highest penetration power and lowest energy.
5. Electronic Configuration
Electronic configuration is the arrangement of electrons in different orbitals of an atom according to Aufbau principle, Pauli exclusion principle and Hund’s rule.
6. Atomic Size
Atomic size is the distance between nucleus and outermost electron. Across a period it decreases, while down a group it increases.
7. Ionic Size
Ionic size is the size of ion formed after gain or loss of electrons. Cations are smaller than atoms, while anions are larger than atoms.
8. Electron Affinity
Electron affinity is the energy released when an electron is added to a neutral atom.
9. Electronegativity
Electronegativity is the tendency of an atom to attract shared electron pair towards itself.
10. Polarizability
Polarizability is the ability of an electron cloud to get distorted by an external electric field.
11. Oxidation State
Oxidation state is the apparent charge present on an atom in a compound.
Important Formula & Trends
| Topic | Key Point |
|---|---|
| Effective Nuclear Charge | Zeff = Z − S |
| Shielding Order | f > d > p > s |
| Penetration Power | s > p > d > f |
| Atomic Size Across Period | Decreases |
| Atomic Size Down Group | Increases |
| Electron Affinity Across Period | Increases |
| Electronegativity Across Period | Increases |
| Electronegativity Down Group | Decreases |
Important Questions
- Explain effective nuclear charge.
- Explain shielding effect.
- Explain variation of atomic size and ionic size.
- Explain electronic configuration with rules.
- Explain variation of electron affinity.
- Explain variation of electronegativity.
- Explain orbital energies of s, p, d and f orbitals.
- Explain polarizability.
- Explain oxidation states.
- Solve numerical problems on effective nuclear charge.
PYQ Analysis Table
| Topic | Repeated Pattern | Importance |
|---|---|---|
| Effective Nuclear Charge | Definition + numerical | Very Important |
| Electronic Configuration | Rules + examples | Very Important |
| Atomic and Ionic Size | Trend explanation | Very Important |
| Electron Affinity & Electronegativity | Definition + variation | Important |
| Orbital Energies | s, p, d, f order | Important |
| Polarizability | Definition + factors | Important |
Effective Nuclear Charge Numerical
Formula: Zeff = Z − S
Question: Find effective nuclear charge for sodium where Z = 11 and S = 10.
Solution: Zeff = 11 − 10
Final Answer: Effective nuclear charge = 1
Download Chemistry Unit 7 PDFs
Download complete notes, important questions and PYQ analysis for Engineering Chemistry Unit 7.
Download Notes PDFHow to Prepare Unit 7
- Learn periodic trends carefully.
- Memorize Zeff = Z − S formula.
- Practice electronic configuration examples.
- Use tables for atomic size, ionic size and electronegativity trends.
- Prepare effective nuclear charge numerical.
- Write clear definitions for better marks.
Frequently Asked Questions
Is Chemistry Unit 7 important for RGPV exams?
Yes, Unit 7 is important because effective nuclear charge, electronic configuration and periodic trends are frequently asked.
Which topic is most important in Unit 7?
Effective nuclear charge, electronic configuration, atomic size, ionic size, electron affinity and electronegativity are most important.
What is the main formula in Unit 7?
The important formula is Zeff = Z − S, where Z is atomic number and S is shielding constant.
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