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Quiz:   Fullscreen Mode Other note source ⚛️ NUCLEAR MODEL OF THE ATOM 19.1 THE ATOM What is an Atom? ATOM = The smallest unit of a chemical element Structure of Atom ATOM = NUCLEUS + ELECTRONS Part Charge Location Mass Nucleus Positive (+) Center Almost all mass Electrons Negative (−) Orbit around nucleus Very small KEY FACT: Most of atom is EMPTY SPACE! Formation of IONS Neutral Atom: Number of Protons = Number of Electrons LOSE electrons → POSITIVE ION (+) GAIN electrons → NEGATIVE ION (−) Example: - Atom with 11 protons & 11 electrons = neutral - Loses 1 electron → 11 protons & 10 electrons = positive ion (+1) - Gains 1 electron → 11 protons & 12 electrons = negative ion (−1) Gold Foil Experiment (1911) Scientists: Geiger, Marsden, Rutherford Method: Shot alpha (α) particles at thin gold foil Results: Observation Conclusion Most α...

Quiz:   Fullscreen Mode Quiz 2: Fullscreen Mode Chemistry Energy Changes Or Chemical Energetics 🌡️ CHEMISTRY: ENERGY CHANGES 1. Exothermic & Endothermic Reactions Exothermic: Reaction that releases heat to surroundings → Temperature RISES → ΔH is NEGATIVE (ΔH Endothermic: Reaction that absorbs heat from surroundings → Temperature FALLS → ΔH is POSITIVE (ΔH > 0) Type Heat Flow Temperature ΔH Sign Examples Exothermic OUT ↗ RISES ↑ NEGATIVE (−) Combustion, respiration, neutralization Endothermic IN ↘ FALLS ↓ POSITIVE (+) Photosynthesis, thermal decomposition 2. Enthalpy Change (ΔH) Enthalpy Change (ΔH): Transfer of thermal energy during a reaction, measured in kilojoules (kJ) Main Formula: ΔH = Total energy of products − Total energy of reactants Example 1 (Exothermic): Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s) ΔH = −150 kJ (negative = heat released) Example 2 (...

Quiz 1:   Fullscreen Mode Other Quiz 🧪 METALS & REACTIVITY SERIES: Complete Theory & Formulas 🔬 I. FUNDAMENTAL THEORIES OF METALS 1.1 Electronic Theory of Metallic Bonding Sea of Electrons Model: Metals consist of a lattice of positive metal ions surrounded by a "sea" of delocalized electrons. This explains conductivity, malleability, and ductility. Metal Atom → Metal Ion⁺ + e⁻ M(s) → M⁺(aq) + e⁻ (general form) 1.2 Density Theory & Formula Density is a fundamental physical property that measures mass per unit volume. Density = Mass ÷ Volume ρ = m/V (g/cm³ or kg/m³) High Density Examples Gold: 19.3 g/cm³ Lead: 11.4 g/cm³ Copper: 8.9 g/cm³ ...

Quiz Other Quiz Using Moles - Complete Theory & Formulas Cambridge IGCSE Chemistry - Grade 9 1. The Mole Concept - Core Theory Definition of a Mole A mole is the amount of substance that contains as many elementary entities (atoms, molecules, ions) as there are atoms in exactly 12 grams of carbon-12 . Avogadro's Constant N A = 6.022 × 10 23 mol -1 This means 1 mole of any substance contains 6.022 × 10 23 particles Key Principle: One mole of any substance contains the same number of particles, but the mass depends on the type of particle. 2. Fundamental Formulas 2.1 Mole-Mass Relationship Number of moles (n) = Mass (m) ÷ Molar mass (M) n = m/M Mass (g...

Quiz 1:   Fullscreen Mode Quiz 2:   Fullscreen Mode Trigonometri, Peluang dan Statistik 📊 Rangkuman Rumus Matematika SMA Trigonometri, Peluang dan Statistik Oleh: Agus Salim 📈 1. STATISTIK Statistik adalah cabang matematika yang berkaitan dengan pengumpulan, analisis, interpretasi, presentasi, dan organisasi data. Dalam konteks SMA, fokus utama adalah pada ukuran pemusatan data dan ukuran penyebaran data. 🎯 1.1 Ukuran Pemusatan Data 📊 1.1.1 Rata-rata (Mean) a. Data Tunggal x̄ = (Jumlah semua nilai data) / (Banyaknya data) Keterangan: • x̄ = rata-rata • n = banyaknya data b. Data Kelompok x̄ = (Σ(fi × xi)) / (Σfi) Keterangan: • fi = frekuensi kelas ke-i • ...

Frequency Distribution Table - Sturges Method Frequency Distribution Table Generator Sturges Method Enter data values below (separated by semicolons). Maximum 500 values: Calculate Distribution Results New Calculation