1️⃣ #ALKENES
✔️ Unsaturated hydrocarbons
✔️ Contain one or more C=C double bond
📌 General formula:
✔️ CₙH₂ₙ (one double bond)
📌 Hybridisation:
✔️ Carbon of C=C → sp²
📌 Geometry:
✔️ Trigonal planar (120°)


2️⃣ #NOMENCLATURE
✔️ Longest chain containing C=C
✔️ Lowest number to double bond
✔️ Suffix → –ene
📌 Example:
✔️ CH₂=CH₂ → Ethene


3️⃣ #ISOMERISM ⭐
✔️ Chain isomerism
✔️ Position isomerism
✔️ Geometrical isomerism (cis–trans) ⭐⭐
📌 Condition for geometrical isomerism:
✔️ Each C of C=C attached to two different groups


4️⃣ #PHYSICALPROPERTIES
✔️ Colourless
✔️ Insoluble in water
✔️ Slightly soluble in organic solvents
📌 Boiling point:
✔️ Increases with molar mass
✔️ cis > trans (due to polarity) ⭐


5️⃣ #PREPARATIONOFALKENES
(a) #DEHYDRATIONOFALCOHOL ⭐
✔️ Alcohol → Alkene + H₂O
📌 Reagent:
✔️ Conc. H₂SO₄ (443 K)
✔️ Al₂O₃ (623 K)
📌 Example:
CH₃CH₂OH → CH₂=CH₂
(b) #DEHYDROHALOGENATION ⭐
✔️ Alkyl halide + alcoholic KOH
📌 Example:
CH₃CH₂Cl → CH₂=CH₂
(c) #DEHALOGENATION
✔️ Vicinal dihalide + Zn
📌 Example:
BrCH₂–CH₂Br → CH₂=CH₂


6️⃣ #CHEMICALPROPERTIES ⭐⭐


7️⃣ #ADDITIONREACTIONS ⭐⭐⭐
✔️ Characteristic reaction of alkenes
(a) #HYDROGENATION
✔️ Alkene + H₂ → Alkane
📌 Catalyst:
✔️ Ni / Pt / Pd
📌 Example:
CH₂=CH₂ → CH₃–CH₃
(b) #HALOGENATION ⭐
✔️ Alkene + X₂
📌 Observation:
✔️ Decolourisation of bromine water ⭐
📌 Example:
CH₂=CH₂ + Br₂ → BrCH₂–CH₂Br
(c) #HYDROHALOGENATION ⭐⭐
✔️ Alkene + HX
📌 Follows Markovnikov’s rule
📌 Example:
CH₃–CH=CH₂ + HBr → CH₃–CHBr–CH₃


8️⃣ #MARKOVNIKOVSRULE ⭐⭐⭐
✔️ H adds to C with more H atoms
✔️ X adds to C with less H atoms


9️⃣ #ANTIMARKOVNIKOVRULE (PEROXIDEEFFECT) ⭐⭐
✔️ In presence of peroxide
✔️ Only with HBr
📌 Example:
CH₃–CH=CH₂ + HBr → CH₃–CH₂–CH₂Br


🔟 #HYDRATIONOFALKENES
✔️ Alkene + H₂O → Alcohol
📌 Catalyst:
✔️ Dil. H₂SO₄
📌 Follows Markovnikov rule


1️⃣1️⃣ #OXIDATIONOFALKENES ⭐⭐
(a) Mild oxidation
✔️ Cold alkaline KMnO₄
✔️ Gives vicinal diol (glycol)
📌 Test:
✔️ Baeyer’s test ⭐
(b) Ozonolysis ⭐⭐⭐
✔️ Alkene + O₃
📌 Product:
✔️ Aldehydes / ketones
📌 Used to locate double bond


1️⃣2️⃣ #POLYMERISATION ⭐
✔️ Many alkene molecules → polymer
📌 Example:
✔️ Ethene → Polyethene


1️⃣3️⃣ #STABILITYOFALKENES ⭐
✔️ More substituted alkene → more stable
📌 Order:
✔️ Tetra > Tri > Di > Mono


1️⃣4️⃣ #NEETIMPORTANTPOINTS
✔️ Alkenes show addition reactions
✔️ Markovnikov rule frequently asked
✔️ Peroxide effect only with HBr
✔️ Baeyer test detects C=C
✔️ Ozonolysis → double bond position


1️⃣5️⃣ #ONELINEREVISION
✔️ Alkenes = unsaturated
✔️ Formula = CₙH₂ₙ
✔️ sp² hybridisation
✔️ Addition reactions dominate
✔️ Ozonolysis identifies structure

1️⃣ #SOLUTION
✔️ Homogeneous mixture
✔️ Consists of solute + solvent
📌 Example:
✔️ Sugar in water


2️⃣ #TYPESOFSOLUTIONS
✔️ Solid in liquid → sugar + water
✔️ Liquid in liquid → alcohol + water
✔️ Gas in liquid → CO₂ in water
✔️ Gas in gas → air


3️⃣ #SOLUBILITY ⭐
✔️ Maximum amount of solute that dissolves in a given amount of solvent
✔️ At given temperature & pressure
📌 Units:
✔️ g / 100 g solvent
✔️ mol L⁻¹


4️⃣ #FACTORAFFECTINGSOLUBILITY ⭐⭐
(a) Nature of solute & solvent
✔️ Like dissolves like
✔️ Polar in polar, non-polar in non-polar
(b) Temperature
✔️ Solid in liquid → solubility ↑ with temp
✔️ Gas in liquid → solubility ↓ with temp ⭐
(c) Pressure
✔️ Significant only for gases
✔️ Solubility ↑ with pressure


5️⃣ #HENRYSLAW ⭐⭐⭐
✔️ Solubility of gas ∝ pressure of gas
📌 Statement:
✔️ At constant temperature, amount of gas dissolved is directly proportional to its partial pressure
📌 Formula:
✔️ p = kₕ x
Where:
✔️ p = partial pressure
✔️ x = mole fraction
✔️ kₕ = Henry’s constant
📌 Applications (PYQ):
✔️ Soft drinks
✔️ Scuba diving
✔️ High altitude sickness


6️⃣ #SOLUBILITYOFGASES ⭐⭐
✔️ Increases with pressure
✔️ Decreases with temperature
📌 Example:
✔️ Cold water holds more oxygen


7️⃣ #RAOULTSLAW ⭐⭐⭐
✔️ For ideal solutions
📌 Statement:
✔️ Partial vapour pressure of each component ∝ its mole fraction
📌 Formula:
✔️ pₐ = xₐ pₐ⁰
✔️ Total pressure = pₐ + pᵦ


8️⃣ #IDEALSOLUTION
✔️ Obeys Raoult’s law at all concentrations
✔️ ΔHmix = 0
✔️ ΔVmix = 0
📌 Example:
✔️ Benzene + toluene


9️⃣ #NON-IDEALSOLUTION
✔️ Deviates from Raoult’s law
📌 Types:
✔️ Positive deviation
✔️ Negative deviation


🔟 #POSITIVEDDEVIATION ⭐
✔️ A–B attraction < A–A or B–B
✔️ Vapour pressure ↑
📌 Example:
✔️ Ethanol + acetone


1️⃣1️⃣ #NEGATIVEDEVIATION ⭐
✔️ A–B attraction > A–A or B–B
✔️ Vapour pressure ↓
📌 Example:
✔️ Chloroform + acetone


1️⃣2️⃣ #COLLIGATIVEPROPERTIES ⭐⭐
✔️ Depend only on number of solute particles
📌 Types:
✔️ Relative lowering of vapour pressure
✔️ Elevation of boiling point
✔️ Depression of freezing point
✔️ Osmotic pressure


1️⃣3️⃣ #OSMOTICPRESSURE ⭐⭐
✔️ Pressure required to stop osmosis
📌 Formula:
✔️ π = CRT
✔️ Used to determine molar mass


1️⃣4️⃣ #NEETIMPORTANTPOINTS
✔️ Henry’s law → gases
✔️ Raoult’s law → ideal solutions
✔️ Gas solubility ↓ with temp
✔️ Colligative properties depend on particles
✔️ Osmotic pressure works at room temp


1️⃣5️⃣ #ONELINEREVISION
✔️ Solution = homogeneous mixture
✔️ Solubility depends on T, P, nature
✔️ Henry’s law → p ∝ x
✔️ Raoult’s law → vapour pressure
✔️ Colligative → number of particles

🌟 Such Type Of Electron Pairs Are – 🌟

Two – sp hybridisation
Three – sp2 hybridisation
Four – sp3 hybridisation
Five – sp3d hybridisation
Six – sp3d2 hybridisation
Seven – sp3d3 hybridisation