📘 Grade 9 → Unit 3: Structure of the Atom · Unit 4: Periodic Classification of Elements
Atomic theories, subatomic particles (proton, neutron, electron), atomic number, mass number, isotopes, periodic table trends.
📙 Grade 11 → Unit 1: Atomic Structure and Periodic Properties
Electron configuration, quantum numbers, periodic trends (atomic radius, ionization energy, electronegativity).
English: Atomic number (Z) = number of protons. Mass number (A) = protons + neutrons.
Isotopes = same Z, different A. Electron configuration follows Aufbau, Hund’s rule, Pauli exclusion.
Across a period: atomic radius decreases, ionization energy increases. Down a group: radius increases, ionization energy decreases.
A = Z + N | Example: 12C and 14C are isotopes
Bohr Model of a Carbon atom (Z=6): 2 electrons in shell 1, 4 in shell 2
በጣም ግልፅ አማርኛ (ከEnglish ጋር):
Atomic number (Z) = የፕሮቶን ቁጥር። Mass number (A) = ፕሮቶን + ኒውትሮን። Isotopes = ተመሳሳይ Z፣ የተለያየ A (ምሳሌ፡ 12C እና 14C)።
Electron configuration፡ Aufbau → Hund’s rule → Pauli exclusion።
በperiod ውስጥ ከግራ ወደ ቀኝ፡ atomic radius ይቀንሳል፣ ionization energy ይጨምራል።
“Protons decide the element (Z). Neutrons change the isotope (A).”
📘 Grade 9 → Unit 5: Chemical Bonding
Ionic bond, covalent bond, metallic bond — basic ideas.
📙 Grade 11 → Unit 2: Chemical Bonding
Lewis structures, VSEPR theory, polarity, intermolecular forces (hydrogen bond, dipole-dipole, London forces).
English: Ionic bond = transfer of electrons (metal + non-metal). Covalent bond = sharing of electrons (non-metal + non-metal).
VSEPR predicts molecular shape. Electronegativity difference: large → ionic, small → covalent.
Hydrogen bonding is the strongest intermolecular force (in H₂O, NH₃, HF).
Na → Na⁺ + e⁻ | Cl + e⁻ → Cl⁻ | Na⁺ + Cl⁻ → NaCl
በጣም ግልፅ አማርኛ (ከEnglish ጋር):
Ionic bond = electron ማስተላለፍ (metal + non-metal)። ምሳሌ፡ NaCl። Covalent bond = electron ማጋራት (non-metal + non-metal)። ምሳሌ፡ H₂O, CO₂። Hydrogen bond = በጣም ጠንካራ intermolecular force (በH₂O, NH₃, HF)።
Ionic vs covalent, Lewis structures እና hydrogen bonding በentrance ላይ በጣም ብዙ ጊዜ ይመጣሉ!
3. Chemical Reactions እና Stoichiometry
📗 Grade 10 → Unit 1: Chemical Reactions and Stoichiometry
Types of reactions, balancing equations, mole concept, molar mass, stoichiometry calculations.
English: 1 mole = 6.022 × 10²³ particles (Avogadro’s number).
Molar mass = mass of 1 mole (g/mol). From balanced equation, mole ratios give the amounts of reactants/products.
Always balance the equation first before any calculation.
2H₂ + O₂ → 2H₂O | n = mM | NA = 6.022 × 10²³
በጣም ግልፅ አማርኛ (ከEnglish ጋር):
1 mole = 6.022 × 10²³ particles (Avogadro’s number)። Molar mass (M) = የ1 mole ክብደት (g/mol)።
ቁጥር n = mM (m = mass በgram)።
ስሌት ከመጀመርዎ በፊት equation ማመጣጠን (balance) ግዴታ ነው።
“Mole is the bridge between mass and number of particles.” Always start from the balanced equation.
📗 Grade 10 → Unit 4: Energy Changes and Electrochemistry
Exothermic/endothermic reactions, enthalpy, galvanic cells, electrolysis.
English: Exothermic = heat released (ΔH negative). Endothermic = heat absorbed (ΔH positive).
In a galvanic cell: oxidation at anode, reduction at cathode (OIL RIG: Oxidation Is Loss, Reduction Is Gain of electrons).
Electrolysis uses electricity to drive non-spontaneous reactions.
ΔH < 0 → exothermic | ΔH > 0 → endothermic
በጣም ግልፅ አማርኛ (ከEnglish ጋር):
Exothermic = ሙቀት ይወጣል (ΔH አሉታዊ)። Endothermic = ሙቀት ይገባል (ΔH አዎንታዊ)።
Galvanic cell፡ oxidation በanode፣ reduction በcathode።
OIL RIG = Oxidation Is Loss, Reduction Is Gain (of electrons)።
“OIL RIG — Oxidation Is Loss, Reduction Is Gain of electrons.” Anode = oxidation, Cathode = reduction.
📙 Grade 11 → Unit 4: Chemical Kinetics · Unit 5: Chemical Equilibrium
Rate of reaction, factors affecting rate, collision theory, equilibrium constant (Kc, Kp), Le Chatelier’s principle.
English: Rate increases with concentration, temperature, surface area, and catalysts.
At equilibrium, forward rate = reverse rate. Kc = [products] ÷ [reactants] (with stoichiometric powers).
Le Chatelier: if you stress a system at equilibrium, it shifts to relieve the stress.
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