5.1 Physical Properties

1.1 Physical Properties
1.2 Chemical Properties

3.1 Borax
3.2 Orthoboric acid ($H_3BO_3$)
3.3 Diborane ($B_2H_6$)
3.4 Boron Halides $(BX_3)$

5.1 Physical Properties
5.2 Chemical Properties

6.1 Diamond
6.2 Graphite
6.3 Fullerene

7.1 Carbon Monoxide $(CO)$
7.2 Carbon Dioxide $(CO_2)$

8.1 Compounds of Silicon

9.1 Important compounds of Nitrogen

10.1 Nitrogen Oxide $N_2O$ or Laughing gas (Neutral)
10.2 Nitric Oxide $NO$ (Neutral)
10.3 Nitrogen trioxide $N_2O_3$
10.4 Nitrogen dioxide or Di-nitrogen tetroxide $NO_2$ or $N_2O$
10.5 Nitrogen pentaoxide $N_2O_5$

11.1 Nitric acid $HNO_3$
11.2 Oxidation of Metalloid and Inorganic compounds by Nitric acid
11.3 Action of Metals & Proteins

13.1 Ozone

14.1 Oxides of Sulphur
14.2 Oxyacids of Sulphur

Covalent Radii: There is an increase in covalent radii from $C$ to $Si$, thereafter from $Si$ to $Pb$ a small increase in radius due to the presence of completely filled $d$ and $f$ orbitals in heavier members.

Ionisation Energies: The higher ionization energies than group $13$ is due to the higher nuclear charge and smaller size of atoms of group $14$ elements. While moving down the group, the ionisation energies decreases till $Sn$. From $Sn$ to $Pb$ as a consequence of poor shielding effect of intervening $d$ and $f$ orbitals and increase in size of the atom, ionisation energy increases. $$C>Si>Ge>Sn<Pb$$

Catenation: It is the ability of the atoms to link with one another through covalent bonds. Its tendency decreases from $C$ to $Pb$ due to the decreasing $M-M$ single bond energy.

Allotropy: Except lead all other elements exhibit allotropy. Allotropic forms are:

$C$: crystalline and microcrystalline

$Si$: crystalline and amorphous

$Ge$: $2$ crystalline forms

$Sn$: $3$ solid forms (grey tin, white tin and rhombic tin)