Chemistry
What the exam tests
Kankor chemistry spans atomic structure, the periodic table, chemical bonding, moles and stoichiometry, acids and bases, oxidation–reduction, and an introduction to organic chemistry.
Concepts to master
- Atomic structure: protons define the element, neutrons define the isotope, electrons define charge.
- Periodic trends: atomic radius decreases across a period; electronegativity increases across and decreases down.
- Bonding: ionic (metal + nonmetal, electron transfer), covalent (nonmetals, sharing), metallic.
- The mole: one mole = 6.022 × 10²³ particles; molar mass in g/mol.
- Acids and bases: pH scale, neutralization, and the meaning of strong versus concentrated.
Common traps
- Confusing atomic number with mass number.
- Thinking "strong acid" means "concentrated acid" - strength is about dissociation, not amount.
- Forgetting to balance equations before using mole ratios.
- Mixing up oxidation (loss of electrons) with reduction (gain).
- Assuming all covalent compounds are non-conductors in every state - some ionize in water.
Worked example
How many moles are in 18 g of water? Molar mass of H₂O = 2(1) + 16 = 18 g/mol. Moles = mass ÷ molar mass = 18 ÷ 18 = 1 mol. Rule of thumb: always convert grams to moles first, then use the balanced equation's coefficients as the ratio.