The p-block Groups 13–14 (supplementary)

Group 13 — boron family

Supplementary note: some CBSE Class 11 schedules no longer examine this full chapter. Use only if your school still teaches it.

B, Al, Ga, In, Tl: three valence electrons. Boron is non-metal; others are metals. Al is the workhorse (bauxite → Hall–Héroult aluminium).

Boron: electron-deficient compounds (BF₃ accepts NH₃). Borax and boric acid are syllabus names. Aluminium: amphoteric Al₂O₃ and Al(OH)₃ react with acids and bases.

Down the group: increasing metallic character; +1 state stabilises for Tl (inert pair effect) — a trend question favourite.

Group 14 — carbon family

C, Si, Ge, Sn, Pb: four valence electrons. Carbon catenates; silicon forms silicates and silicone polymers at intro level.

Allotropes of carbon: diamond (3-D network, hard), graphite (layers, lubricant, conductor), fullerenes and nanotubes (intro mention). CO and CO₂: CO is toxic (binds haemoglobin); CO₂ is acidic oxide.

Silicones: R₂SiO chains; inert, water-repellent. Silicates: SiO₄ tetrahedra in minerals — know the tetrahedron picture, not every mineral name.

Oxides and acid–base character

Across a period, oxides become more acidic; down a metal group, oxides become more basic. Al₂O₃ and ZnO (if you met them) are amphoteric bridges.

Boric acid H₃BO₃ is weak Lewis acid; carbonic acid from CO₂ + water is weak diprotic in theory. Compare with nitric and sulphuric acids in later groups when you reach Class 12 p-block.