Quick answer: Le Chatelier’s Principle states that when a system at dynamic equilibrium is disturbed by a change in concentration, pressure, or temperature, the equilibrium shifts to oppose the change. In H2 Chemistry, three rules carry most of the marks: Le Chatelier’s Principle is one of the most heavily examined ideas in H2 Chemistry ChemicalContinue reading “Le Chatelier’s Principle Explained: H2 Chemistry Guide”
Category Archives: Chemistry Tuition
O Level Combined Science Syllabus 2026: Chemistry & Biology Explained
Quick answer: O-Level Combined Science (Chemistry, Biology), syllabus 5088, leaves out several Pure Science topics that come back in JC. In H2 Chemistry, the biggest gaps are: In H2 Biology, the biggest gaps are: Combined Science students can take H2 Chemistry or H2 Biology at many JCs. The students who do best close these specificContinue reading “O Level Combined Science Syllabus 2026: Chemistry & Biology Explained”
Sec 3 Chemistry Tuition Singapore: What to Expect
Quick answer: Sec 3 is the first year of Pure Chemistry. It covers the foundation topics the rest of the course is built on: Students in Sec 3 in 2026 are the first cohort to sit the new Singapore-Cambridge Secondary Education Certificate (SEC) in 2027. They take Pure Chemistry at G3 level, which uses theContinue reading “Sec 3 Chemistry Tuition Singapore: What to Expect”
Electron Affinity Explained: H2 Chemistry Guide
Quick answer: First electron affinity is the enthalpy change when one mole of gaseous atoms each gains one electron to form one mole of gaseous 1− ions. It is usually negative (energy released). The second electron affinity is always positive, because the incoming electron is repelled by the ion’s existing negative charge. Electron affinity explainsContinue reading “Electron Affinity Explained: H2 Chemistry Guide”
Lattice Energy Explained (H2 Chemistry)
Quick answer: Lattice energy is the enthalpy change when one mole of an ionic solid forms from its gaseous ions under standard conditions. It is negative because lattice formation releases energy. Its magnitude increases with higher ionic charge and smaller ionic radius, and you find it from a Born-Haber cycle using Hess’s law. Lattice energyContinue reading “Lattice Energy Explained (H2 Chemistry)”
O Level Chemistry Syllabus 2026 Explained
Quick answer: The 2026 Singapore-Cambridge GCE O-Level Pure Chemistry syllabus (6092) has 12 topics in three sections and is assessed through three compulsory papers: Paper 1 (40 multiple-choice questions, 30%), Paper 2 (structured and free-response, 80 marks, 50%) and Paper 3 (practical, 40 marks, 20%). Chemistry within Combined Science (5086 and 5088) uses the sameContinue reading “O Level Chemistry Syllabus 2026 Explained”
Transition Metals Explained: H2 Chemistry Guide (9476)
Quick answer: A transition element is a d-block element that forms at least one stable ion with an incomplete d subshell — which is why zinc (Zn²⁺ = [Ar]3d¹⁰) doesn’t qualify despite being in the d-block. Chromium ([Ar]3d⁵4s¹) and copper ([Ar]3d¹⁰4s¹) are the two classic exceptions to the expected filling pattern. Transition metals show variableContinue reading “Transition Metals Explained: H2 Chemistry Guide (9476)”
Electronegativity Explained: H2 Chemistry Guide (9476)
Quick answer: Electronegativity is the ability of a bonded atom to attract the shared pair of electrons towards itself. It generally increases across a period — from 0.93 (sodium) to 3.16 (chlorine) on the Pauling scale — because nuclear charge rises while shielding barely changes. It generally decreases down a group, since added shells increaseContinue reading “Electronegativity Explained: H2 Chemistry Guide (9476)”
Atomic Radius Explained: H2 Chemistry Guide (9476)
Quick answer: Atomic radius decreases across a period (rising nuclear charge, shielding barely changes) and increases down a group (extra occupied shells outweigh the higher nuclear charge). Sodium’s atomic radius is 0.157 nm versus chlorine’s 0.099 nm across Period 3; magnesium’s is 0.160 nm versus barium’s 0.217 nm down Group 2. Ionic radius follows theContinue reading “Atomic Radius Explained: H2 Chemistry Guide (9476)”
Shielding Effect Explained: H2 Chemistry Guide (9476)
Quick answer: The shielding effect is the reduction in nuclear attraction felt by an outer electron because inner-shell electrons repel it — the nucleus’s charge hasn’t weakened, the outer electron simply doesn’t experience all of it. Shielding barely changes across a period, since added electrons enter the same principal shell, but increases substantially down aContinue reading “Shielding Effect Explained: H2 Chemistry Guide (9476)”
