⚗️ DAE Mechanical — 1st Year — Subject Code 112
Chemistry
Complete Notes — Easy English
Atomic Structure · Chemical Bonding · Reactions · Organic Chemistry · Complete Curriculum
Atomic Theory
Chemical Reactions
Organic Compounds
Unit 1
Atomic Structure
Fundamental Concepts
Dalton's Atomic Theory
- Matter consists of atoms
- Atoms of element are identical
- Atoms combine in fixed ratios
- Atoms cannot be created/destroyed
Subatomic Particles
| Particle | Charge | Location | Mass |
|---|---|---|---|
| Proton | +1 | Nucleus | 1 amu |
| Neutron | 0 | Nucleus | 1 amu |
| Electron | -1 | Orbitals | 1/1836 amu |
Bohr's Model
- Electrons orbit nucleus in shells
- Energy levels: K, L, M, N...
- Maximum electrons: 2n²
Electron Configuration
Order of filling: 1s² 2s² 2p⁶ 3s² 3p⁶...
✏️ Practice: Write electron configurations for elements
Unit 2
Periodic Table and Properties
Organization and Trends
Periodic Table Structure
- Periods: Horizontal rows (8 periods)
- Groups: Vertical columns (18 groups)
- Blocks: s, p, d, f regions
Periodic Properties
| Property | Trend | Reason |
|---|---|---|
| Atomic Radius | Decreases left to right | Nuclear charge |
| Ionization Energy | Increases left to right | Easier to remove electrons |
| Electronegativity | Increases left to right | Attraction for electrons |
Element Categories
- Metals: Alkali, Alkaline earth, Transition
- Non-metals: Halogens, Noble gases
- Metalloids: Semi-metals
✏️ Practice: Predict element properties using periodic trends
Unit 3
Chemical Bonding
Types and Formation
Ionic Bonding
- Complete electron transfer
- Forms cations and anions
- Example: NaCl (sodium chloride)
Covalent Bonding
- Electrons shared between atoms
- Single, double, triple bonds
- Examples: H₂, O₂, CO₂
Metallic Bonding
- Sea of delocalized electrons
- Properties: Conductivity, malleability
Bond Characteristics
| Type | Electronegativity Diff | Character |
|---|---|---|
| Ionic | >1.7 | Complete transfer |
| Polar Covalent | 0.4-1.7 | Partial transfer |
| Nonpolar Covalent | <0.4 | Equal sharing |
✏️ Practice: Classify bonds and predict compound properties
Unit 4
Chemical Reactions
Types and Equations
Reaction Types
- Synthesis: A + B → AB
- Decomposition: AB → A + B
- Single Displacement: A + BC → AC + B
- Double Displacement: AB + CD → AD + CB
- Combustion: Fuel + O₂ → CO₂ + H₂O
Balancing Equations
Use coefficients to balance atoms on both sides. Practice with examples like:
2H₂ + O₂ → 2H₂O (water formation)
Stoichiometry
- Molar ratios from balanced equations
- Limiting reactant determination
- Percent yield calculations
✏️ Practice: Balance chemical equations and solve stoichiometry problems
Unit 5
Acids and Bases
Properties and Reactions
Arrhenius Definition
- Acids: Produce H⁺ ions (HCl, H₂SO₄)
- Bases: Produce OH⁻ ions (NaOH, NH₃)
pH Scale
- Range: 0-14
- Neutral: pH = 7 (pure water)
- Acidic: pH < 7
- Basic: pH > 7
- pH = -log[H⁺]
Neutralization Reaction
Acid + Base → Salt + Water
HCl + NaOH → NaCl + H₂O
Titration
- Determine concentration of unknown
- Using standard solution
- Indicator color change at endpoint
✏️ Practice: Calculate pH and perform acid-base titrations
Unit 6
Organic Chemistry Basics
Carbon Compounds
Hydrocarbons
- Alkanes: C-C single bonds (CₙH₂ₙ₊₂)
- Alkenes: C=C double bonds (CₙH₂ₙ)
- Alkynes: C≡C triple bonds (CₙH₂ₙ₋₂)
Functional Groups
| Group | Formula | Type |
|---|---|---|
| Alcohol | -OH | Hydroxyl |
| Aldehyde | -CHO | Carbonyl |
| Carboxylic Acid | -COOH | Acidic |
Isomerism
- Structural: Different connectivity
- Geometric: Different spatial arrangement
✏️ Practice: Name organic compounds and identify isomers
Unit 7
Solutions and Concentration
Dissolving Substances
Solution Components
- Solute: Dissolved substance
- Solvent: Dissolving medium
- Solution: Homogeneous mixture
Concentration Units
| Unit | Definition |
|---|---|
| Molarity (M) | mol solute / L solution |
| Molality (m) | mol solute / kg solvent |
| Percent (w/w) | (mass solute / mass solution) × 100 |
Solubility Factors
- Temperature (usually increases)
- Pressure (gases affected)
- Nature of solute and solvent
✏️ Practice: Calculate molarity and prepare solutions
Unit 8
Thermochemistry
Heat and Energy in Reactions
Enthalpy
- ΔH: Change in enthalpy
- Exothermic: ΔH negative (releases heat)
- Endothermic: ΔH positive (absorbs heat)
Types of Reactions
| Type | ΔH | Example |
|---|---|---|
| Exothermic | Negative | Combustion |
| Endothermic | Positive | Melting ice |
Hess's Law
Enthalpy of overall reaction equals sum of steps.
✏️ Practice: Calculate enthalpy changes using Hess's Law
✨ Congratulations!
You've completed Chemistry! Master the science of matter and reactions.
