Elements and Compounds
Basic chemistry concepts about elements, compounds and mixtures. Important element types, atomic number, mass number and key compounds for TNPSC exams.
Learning Content
🔬 Elements (Elements) - Introduction!
Element = made up of the same type of atoms | A total of 118 elements
📊 Element types - MASTER TABLE
| Type | count | Properties | Example |
|---|---|---|---|
| Metals | 91 | Electrical conductor, luster, flexibility | Fe, Cu, Au, Ag, Al |
| Metals | 22 | Non-conductive and brittle | C, N, O, S, P |
| Forgings | 5 | Both properties | B, Si, Ge, As, Te |
⚛️ Major Elements – Atomic Number
| H (Hydrogen) | 1 | Light element |
| He (Helium) | 2 | First coloring gas |
| C (Carbon) | 6 | Organic compounds are basic |
| N (Nitrogen) | 7 | 78% in air |
| O (Oxygen) | 8 | 21% in air, biogas |
| Na (Sodium) | 11 | is in salt |
| Fe (Iron) | 26 | The most common metal |
| Cu (Copper) | 29 | Electrical conductor |
| Au (gold) | 79 | Precious metal |
💡 MEMORY TRICK - Top 10 Elements
"H He Li Be B C N O F Ne"
🎯"Hi Hero Little Baby Boy Come Near Auhar Best Name"
🧪 Compounds & Compounds!
📊 Element vs Compound vs Compound
| feature | the element | compound | composition |
|---|---|---|---|
| structure | single atoms | different atoms | Different products |
| Can it be separated? | Can't | Chemical method | Physical method |
| ratio | - | Fixed rate | will change |
| Example | Fe, Cu, O₂ | H₂O, NaCl, CO₂ | Air, sea water |
🔬 Key compounds - MASTER TABLE
| compound | formula | Another name | benefit |
|---|---|---|---|
| Water | H₂O | - | Survival |
| Salt | NaCl | Sodium Chloride | Food, processing |
| lime | CaCO₃ | Calcium carbonate | Construction |
| Soda | Na₂CO₃ | Sodium carbonate | Laundry |
| Baking soda | NaHCO₃ | Sodium bicarbonate | Food, medicine |
| Gypsum | CaSO₄.2H₂O | Calcium sulfate | Plaster, cement |
| Ammonia | NH₃ | - | Compost, clean up |
| Carbon dioxide | CO₂ | - | Soda, Fire |
🎯 Combination types
| Equivalent composition | Homogeneous | Air, salt water, sugar water |
| Asymmetric mixing | Heterogeneous | Sand + water, oil + water |
⚙️ Metal vs Metal - Comparison!
📊 MASTER COMPARISON TABLE
| trait | Metal | Metal |
|---|---|---|
| condition | Solid (except Hg) | Solid/Liquid/Gas |
| Conduction of electricity | transmit | Nonconductive (except C) |
| Heat conduction | Good conductor | Bad conductor |
| Shine | has | No (except I₂, C) |
| to beat | Malleable | will break |
| to pull | Ductile | will not |
| the sound | sonorous | Does not sound |
| density | A lot | less |
🥇 Major Metals - Specialties
| Au (gold) | A very ductile metal |
| Ag (Silver) | Excellent electrical/heat conductor |
| Cu (Copper) | Useful for electrical wires |
| Al (aluminum) | Light metal, aircraft |
| Fe (Iron) | Very useful |
| Hg (Mercury) | liquid metal |
| W (tungsten) | High melting point (3422°C) |
💡 Memory SHORTCUTS
🎯"MDSS"= Malleable, Ductile, Sonorous, Shiny - metallic properties!
🎯Liquid metal = Hg (mercury)- Mercury thermometer!
🎯Conductive metal = C (graphite)- Pencil lead!
📝 TNPSC Main Questions & Shortcuts!
🎯 Frequently Asked Questions
| Q: How many total elements are there? | ✅ 118 |
| Q: Light element? | ✅ Hydrogen (H) |
| Q: Heaviest element? | ✅ Osmium (Os) |
| Q: Liquid metal? | ✅ Mercury (Hg) |
| Q: Liquid metal? | ✅ Bromine (Br) |
| Q: What is the most common gas in air? | ✅ Nitrogen (78%) |
| Q: Biogas? | ✅ Oxygen (O₂) |
| Q: Best electrical conductor? | ✅ Silver (Ag) |
| Q: Chemical name of NaCl? | ✅ Sodium Chloride |
| Q: Baking soda formula? | ✅ NaHCO₃ |
| Q: High melting point metal? | ✅ Tungsten (W) - 3422°C |
| Q: Metal in electric bulb? | ✅ Tungsten (W) |
💡 SUPER SHORTCUTS
🔵 Composition of Air:
N₂ = 78%
O₂ = 21%
Others = 1%
💡 "78-21-1"
🔴 Counterfeit Metals (5):
B, Si, Ge, As, Te
💡 "PCJESTE"
🔢 Atomic Number - QUICK MEMORY
| H=1, He=2, Li=3, Be=4, B=5 |
| C=6, N=7, O=8, F=9, Ne=10 |
| Na=11, Mg=12, Al=13, Si=14, P=15 |
| S=16, Cl=17, Ar=18, K=19, Ca=20 |
| Fe=26, Cu=29, Zn=30, Au=79, Ag=47 |
🎯 The formula is MATCH
| Water | H₂O |
| Salt | NaCl |
| lime | CaCO₃ |
| Baking soda | NaHCO₃ |
| Soda | Na₂CO₃ |
| Ammonia | NH₃ |
| Sulfuric acid | H₂SO₄ |
| Hydrochloric acid | HCl |
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