Kerala SSLC Chemistry: Periodic Trends, Moles, Electrochemistry and Organic Naming
Kerala SSLC Chemistry (Science Part 2) rewards application: predict a periodic trend, convert mass ↔ moles ↔ gas volume, decide a displacement or cell reaction, and name a carbon compound.
What the exam tests
Questions are short-answer and structured, built on the SCERT Kerala Class 10 Chemistry units: periodic table and periodic properties, mole concept and stoichiometry, reactivity series and electrochemistry, and nomenclature and isomerism of organic compounds.
Periodic trends
Modern periodic law: properties are periodic functions of atomic number, so elements are ordered by Z, not atomic mass. Across a period nuclear charge rises while shell number stays constant: atomic radius falls, ionisation energy and electronegativity rise, metallic character falls. Down a group a shell is added, so radius rises and ionisation energy falls. Group 1 alkali metals; group 17 halogens; group 18 noble gases.
Moles
One mole contains 6.022 × 10²³ particles; molar mass in g mol⁻¹ equals the formula mass in u; one mole of any gas occupies 22.4 L at STP (273 K, 1 atm). n = m/M and, for a gas at STP, n = V/22.4.
Reactivity and cells
K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Ag, Au. Metals above hydrogen displace H₂ from acids, and a metal higher in the series displaces a lower one from its salt solution. Oxidation is at the anode, reduction at the cathode; the anode is negative in a galvanic cell but positive in an electrolytic cell.
Organic naming
Alkane CnH2n+2, alkene CnH2n, alkyne CnH2n−2. Number the longest chain to give the lowest locant set. Suffixes: -ol alcohol, -al aldehyde, -one ketone, -oic acid carboxylic acid. Isomers share a molecular formula but differ in structure.
Worked example
Burning 8 g of methane: what mass of CO₂ forms? CH₄ + 2O₂ → CO₂ + 2H₂O. M(CH₄) = 16, so n = 8/16 = 0.5 mol. One mole CH₄ gives one mole CO₂, so n(CO₂) = 0.5 mol. Mass = 0.5 × 44 = 22 g.
Traps
- Ordering by atomic mass instead of atomic number.
- Using 22.4 L mol⁻¹ for solids or non-STP gases.
- Setting mole ratios from an unbalanced equation.
- Swapping anode signs for galvanic vs electrolytic cells.
- Numbering a chain from the end giving higher locants.