Class 11 Chemistry Complete Notes - Physical and Inorganic Chemistry
Comprehensive Class 11 Chemistry notes covering Physical Chemistry (States of Matter, Atomic Structure) and Inorganic Chemistry (Periodic Properties, Chemical Bonding) for NEB.
Table of Contents
Table of Contents
Introduction to Class 11 Chemistry#
Class 11 Chemistry under NEB covers Physical Chemistry, Inorganic Chemistry, and Organic Chemistry basics. This guide focuses on Physical and the next post cover the complete syllabus.
Physical Chemistry#
Unit 1: States of Matter#
Gas Laws
| Law | Equation | Variables | Constant |
|---|---|---|---|
| Boyle's | PV = constant | P, V | T, n |
| Charles's | V/T = constant | V, T | P, n |
| Gay-Lussac's | P/T = constant | P, T | V, n |
| Avogadro's | V/n = constant | V, n | P, T |
| Ideal Gas | PV = nRT | P, V, n, T | R = 0.0821 L·atm/mol·K |
Dalton's Law of Partial Pressures
Ptotal = P1 + P2 + P3 + ... = ΣPi Pi = Xi × Ptotal (where Xi = mole fraction)
Graham's Law of Diffusion
Rate1/Rate2 = √(M2/M1) (inversely proportional to square root of molar mass)
2 moles of gas at 300 K in 10 L. Find pressure. P = nRT/V = 2 × 0.0821 × 300 / 10 = 4.926 atm
Kinetic Molecular Theory
- Gas particles are in constant random motion
- Volume of particles is negligible
- No intermolecular forces
- Collisions are perfectly elastic
- Average KE ∝ absolute temperature
Real Gases - Van der Waals Equation
(P + an²/V²)(V - nb) = nRT
- a: accounts for intermolecular attraction
- b: accounts for molecular volume
Unit 2: Atomic Structure#
Bohr's Model
| Postulate | Description |
|---|---|
| 1 | Electrons in fixed circular orbits |
| 2 | Angular momentum quantized: mvr = nh/2π |
| 3 | Energy change: ΔE = hν = Ef - Ei |
| 4 | Ground state = lowest energy (n=1) |
Energy of Electron in nth Orbit
En = -13.6/n² eV (for hydrogen) rn = 0.529 n² Å
Hydrogen electron from n=3 to n=2. Find wavelength.
ΔE = 13.6(1/4 - 1/9) = 13.6 × 5/36 = 1.89 eV λ = 1240/1.89 ≈ 656 nm (Balmer series, red line)
Quantum Numbers
| Quantum Number | Symbol | Values | Significance |
|---|---|---|---|
| Principal | n | 1, 2, 3... | Shell, energy, size |
| Azimuthal | l | 0 to n-1 | Subshell (s,p,d,f), shape |
| Magnetic | ml | -l to +l | Orbital orientation |
| Spin | ms | +½, -½ | Electron spin |
Electronic Configuration Rules
- Aufbau Principle: Fill lower energy first (1s, 2s, 2p, 3s, 3p, 4s, 3d...)
- Pauli Exclusion: No two electrons with same 4 quantum numbers
- Hund's Rule: Maximize unpaired electrons in degenerate orbitals
- (n+l) Rule: Lower (n+l) fills first; if equal, lower n fills first
- Cr (24): [Ar] 4s¹ 3d⁵ (half-filled d is stable)
- Cu (29): [Ar] 4s¹ 3d¹⁰ (filled d is stable)
- Fe (26): [Ar] 4s² 3d⁶
Unit 3: Chemical Bonding#
Ionic Bond
Formed by complete electron transfer.
| Property | Description |
|---|---|
| Formation | Metal + Non-metal |
| Electronegativity difference | > 1.7 |
| Conductivity | Conducts in molten/aqueous state |
| Melting/Boiling | High |
| Solubility | Soluble in polar solvents |
Covalent Bond
| Type | Electronegativity Diff | Example |
|---|---|---|
| Non-polar covalent | < 0.4 | H₂, Cl₂, O₂ |
| Polar covalent | 0.4 - 1.7 | H₂O, NH₃, HCl |
| Coordinate (dative) | Both electrons from one atom | NH₄⁺, H₃O⁺ |
VSEPR Theory
| Steric Number | Shape | Bond Angle | Examples |
|---|---|---|---|
| 2 | Linear | 180° | CO₂, BeCl₂ |
| 3 | Trigonal planar | 120° | BF₃, SO₃ |
| 3 (1 lone pair) | Bent/V-shaped | ~119° | SO₂, O₃ |
| 4 | Tetrahedral | 109.5° | CH₄, CCl₄ |
| 4 (1 lone pair) | Trigonal pyramidal | ~107° | NH₃, PCl₃ |
| 4 (2 lone pairs) | Bent/V-shaped | ~104.5° | H₂O, OF₂ |
| 5 | Trigonal bipyramidal | 90°, 120° | PCl₅ |
| 6 | Octahedral | 90° | SF₆ |
Hybridization
| Steric No. | Hybridization | Geometry | Example |
|---|---|---|---|
| 2 | sp | Linear | BeCl₂, CO₂ |
| 3 | sp² | Trigonal planar | BF₃, C₂H₄ |
| 4 | sp³ | Tetrahedral | CH₄, NH₃, H₂O |
| 5 | sp³d | Trigonal bipyramidal | PCl₅ |
| 6 | sp³d² | Octahedral | SF₆ |
- CH₄: C (sp³), 4 σ bonds
- C₂H₄: Each C (sp²), 3 σ + 1 π
- C₂H₂: Each C (sp), 2 σ + 2 π
- BF₃: B (sp²), 3 σ bonds
- NH₃: N (sp³), 3 σ + 1 lone pair
Molecular Orbital Theory
- Bond Order = (Nb - Na)/2
- Bond order > 0 → stable
- Paramagnetic if unpaired electrons in MOs
- Diamagnetic if all paired
| Molecule | Configuration | Bond Order | Magnetic |
|---|---|---|---|
| H₂ | σ1s² | 1 | Diamagnetic |
| He₂ | σ1s² σ*1s² | 0 | Unstable |
| N₂ | σ2s² σ*2s² π2p⁴ σ2p² | 3 | Diamagnetic |
| O₂ | σ2s² σ2s² σ2p² π2p⁴ π2p² | 2 | Paramagnetic |
| F₂ | σ2s² σ2s² σ2p² π2p⁴ π2p⁴ | 1 | Diamagnetic |
Unit 4: Periodic Properties#
Trends in Periodic Table
| Property | Across Period | Down Group | Reason |
|---|---|---|---|
| Atomic Radius | Decreases | Increases | Effective nuclear charge / shells |
| Ionization Energy | Increases | Decreases | Nuclear attraction / shielding |
| Electron Affinity | Increases | Decreases | Nuclear attraction / distance |
| Electronegativity | Increases | Decreases | Nuclear attraction / distance |
| Metallic Character | Decreases | Increases | Electron loss tendency |
Exceptions: IE drops from Group 2→13 (Be→B), 15→16 (N→O) due to subshell stability. EA of Cl > F due to small size repulsion in F.
Inorganic Chemistry#
Unit 5: Hydrogen#
| Property | Detail |
|---|---|
| Position | Group 1 and 17 (unique) |
| Isotopes | Protium (¹H), Deuterium (²H), Tritium (³H) |
| Preparation | Zn + 2HCl → ZnCl₂ + H₂↑ |
| Uses | NH₃ synthesis, HCl, hydrogenation, fuel |
Unit 6: Alkali Metals (Group 1)#
| Property | Trend | Note |
|---|---|---|
| Reactivity with water | Increases down | Li < Na < K < Rb < Cs |
| Flame color | Li: Crimson, Na: Golden yellow, K: Lilac, Rb: Red-violet, Cs: Blue | |
| Oxides | Li₂O, Na₂O₂, KO₂, RbO₂, CsO₂ | Peroxide/Superoxide stability increases |
Unit 7: Alkaline Earth Metals (Group 2)#
| Property | Comparison with Group 1 |
|---|---|
| Hardness | Harder |
| Melting/Boiling points | Higher |
| Reactivity | Less reactive |
| Ionization energy | Higher |
| Solubility of hydroxides | Increases down (Be(OH)₂ insoluble) |
| Solubility of sulfates | Decreases down |
| Solubility of carbonates | Decreases down |
Unit 8: Boron Family (Group 13)#
- Boron: Non-metal, electron deficient, forms BF₃, B₂O₃
- Aluminium: Amphoteric, protective oxide layer
- Inert pair effect: +1 oxidation state stability increases down group (Tl⁺ > Tl³⁺)
Unit 9: Carbon Family (Group 14)#
- Catenation: C >> Si > Ge ≈ Sn > Pb
- Allotropes of Carbon: Diamond, Graphite, Fullerenes, Graphene
- Oxidation states: +4 and +2 (stability of +2 increases down: Pb²⁺ > Pb⁴⁺)
Unit 10: Nitrogen Family (Group 15)#
- N₂: Triple bond, inert at room temp
- Ammonia: Haber process: N₂ + 3H₂ ⇌ 2NH₃ (Fe, 450°C, 200 atm)
- Ostwald process: 4NH₃ + 5O₂ → 4NO + 6H₂O → HNO₃
- Oxidation states: -3 to +5
Unit 11: Oxygen Family (Group 16)#
- Oxygen: Paramagnetic, forms O₂, O₃ (ozone)
- Sulfur: Allotropes (rhombic, monoclinic), H₂S, SO₂, SO₃, H₂SO₄ (Contact process)
- Oxidation states: -2, +2, +4, +6
Unit 12: Halogens (Group 17)#
| Property | F₂ | Cl₂ | Br₂ | I₂ |
|---|---|---|---|---|
| State | Gas | Gas | Liquid | Solid |
| Color | Pale yellow | Greenish yellow | Reddish brown | Violet |
| Oxidizing power | Strongest | Strong | Moderate | Weak |
| Reactivity | Highest | High | Moderate | Low |
- Interhalogen compounds: XY, XY₃, XY₅, XY₇ (ClF₃, BrF₅, IF₇)
- Oxyacids: HClO, HClO₂, HClO₃, HClO₄ (acid strength increases)
Unit 13: Noble Gases (Group 18)#
- Inert, monatomic, low boiling points
- Compounds: XeF₂, XeF₄, XeF₆, XeO₃, XeOF₄
- Uses: He (balloons, cryogenics), Ne (signs), Ar (welding), Kr/Xe (lamps)
Important Reactions for NEB#
Preparation of Gases:
- H₂: Zn + 2HCl → ZnCl₂ + H₂↑
- O₂: 2KClO₃ → 2KCl + 3O₂↑ (MnO₂ catalyst)
- N₂: NH₄Cl + NaNO₂ → N₂ + 2H₂O + NaCl
- CO₂: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂↑
- NH₃: 2NH₄Cl + Ca(OH)₂ → 2NH₃ + CaCl₂ + 2H₂O
- Cl₂: MnO₂ + 4HCl → MnCl₂ + Cl₂ + 2H₂O
- SO₂: Cu + 2H₂SO₄ → CuSO₄ + SO₂ + 2H₂O
- H₂S: FeS + 2HCl → FeCl₂ + H₂S↑
Qualitative Analysis (Cations):
- Group I: Pb²⁺, Ag⁺ (HCl → white ppt)
- Group II: Cu²⁺, Cd²⁺, Bi³⁺, Hg²⁺ (H₂S in acidic)
- Group III: Fe³⁺, Al³⁺, Cr³⁺ (NH₄OH + NH₄Cl → hydroxide ppt)
- Group IV: Co²⁺, Ni²⁺, Mn²⁺, Zn²⁺ (H₂S in basic)
- Group V: Ba²⁺, Sr²⁺, Ca²⁺ (NH₄)₂CO₃ → carbonate ppt
Practice Problems#
1. Gas Laws: 500 ml gas at 2 atm compressed to 1 atm. New volume? P₁V₁ = P₂V₂ → 2 × 500 = 1 × V₂ → V₂ = 1000 ml
2. Atomic Structure: Wavelength for n=4→2 in He⁺? (Z=2) 1/λ = RZ²(1/n₁² - 1/n₂²) = 109678 × 4 × (1/4 - 1/16) = 109678 × 4 × 3/16 = 82258 cm⁻¹ λ = 121.5 nm
3. Periodic Properties: IE of Mg > Al? Yes. Mg: [Ne]3s² (stable), Al: [Ne]3s²3p¹ (easier to remove p electron)
4. Bonding: Bond order of O₂⁺? O₂: (8-4)/2 = 2. O₂⁺: (8-3)/2 = 2.5
5. Chemical Equilibrium: For N₂ + 3H₂ ⇌ 2NH₃, Kc = [NH₃]²/[N₂][H₂]³ If [N₂]=1M, [H₂]=3M, [NH₃]=2M at eq: Kc = 4/(1×27) = 0.148
Conclusion#
Class 11 Chemistry requires balancing conceptual understanding with problem-solving skills. Physical Chemistry needs formula mastery and numerical practice. Inorganic Chemistry requires understanding trends and memorizing key reactions. Regular revision of periodic properties and bonding concepts is essential.
The best way to have a good idea is to have lots of ideas.
Good luck with your NEB Chemistry preparation!
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