Author Capstone Axis

Atomic Models and Structure 🔍 Discovery of Subatomic Particles Scientists found that atoms contain smaller particles: Protons (+ charge) were discovered in 1919 as the smallest positive ions from hydrogen gas. Neutrons (no charge) were found by Chadwick in 1932 by hitting beryllium with α-particles. They’re slightly heavier than protons. Particle Symbol Charge (C) Mass […]

Developments Leading to Bohr’s Atomic Model 🚫 Problems with Rutherford’s Model If electrons were stationary, the dense nucleus would pull them in due to electrostatic attraction (like a mini Thomson model). It didn’t explain how electrons are distributed around the nucleus or their energies. 🔍 Key Developments for Bohr’s Model Two breakthroughs helped Bohr improve

🔍 Discovery of Sub-Atomic Particles Scientists learned about atoms by studying electricity in gases! Remember this rule: Like charges repel, unlike charges attract ⚡➡️⚡ ⚡ Discovery of Electron Michael Faraday (1830) found electricity causes chemical reactions in solutions, hinting electricity is made of particles. Later, scientists used cathode ray tubes (glass tubes with 2 metal

Understanding Moles and Chemical Formulas ⚖️ 1. Mole Concept Just like “a dozen” means 12 items, 1 mole = 6.022 × 1023 particles (atoms, molecules, etc.). This number is called Avogadro’s Number (NA). Examples: 1 mole H atoms = 6.022 × 1023 H atoms 1 mole H2O = 6.022 × 1023 water molecules 📊 2.

Stoichiometry and Stoichiometric Calculations 🔍 What is Stoichiometry? Stoichiometry deals with calculating masses (and sometimes volumes) of reactants and products in chemical reactions. It comes from Greek words: stoicheion (element) and metron (measure). ⚖️ Balanced Chemical Equations A balanced equation has the same number of atoms of each element on both sides. Example (combustion of

Mole Concept & Molar Masses 1. Why We Need Moles Atoms and molecules are super tiny! 🧪 Even a small amount of any substance contains a huge number of particles. To count them easily, we use the mole (just like “dozen” for 12 items). 2. What is a Mole? 1 mole (mol) = \(6.022 \times

🔥 Dalton’s Atomic Theory (1808) John Dalton proposed these fundamental ideas about atoms: 💧 Matter is made of atoms – tiny, indivisible particles ⚖️ All atoms of an element are identical – same mass & properties 🧪 Compounds form when atoms of different elements combine in fixed ratios 🔄 Chemical reactions rearrange atoms – no

Atomic and Molecular Masses Dalton’s Atomic Theory (1808) John Dalton proposed that: ✨ Matter is made of indivisible atoms. ✨ Atoms of the same element have identical mass; atoms of different elements have different masses. ✨ Compounds form when atoms combine in fixed ratios. ✨ Atoms are rearranged in reactions but never created/destroyed. Limitation: Couldn’t

Measuring Volume in the Lab We use different tools to measure liquids: 🧪 Graduated cylinder Burette Pipette Volumetric flask (for preparing exact volumes) Density: Mass meets Volume Density tells us how tightly packed a material’s particles are! 🔬 Formula: \( \text{Density} = \frac{\text{Mass}}{\text{Volume}} \) Units: SI unit: \(\text{kg m}^{-3}\) Chemist’s favorite: \(\text{g cm}^{-3}\) (easier for

Unit Conversion Magic ✨ When converting units, we use unit factors (fractions equal to 1). Multiply them to switch units without changing the value! Examples: Inches to cm: $$3 \text{ in} = 3 \text{ in} \times \frac{2.54 \text{ cm}}{1 \text{ in}} = 7.62 \text{ cm}$$ Tip: Cancel matching units! ✅ Liters to m³: $$2 \text{