1.1 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

Atomic Radius:

The atomic radius increases from top to bottom in a group. However, a deviation can be seen. Atomic radius of $Ga$ is less than that of $Al$. This can be understood from the variation in the inner core of the electronic configuration. The presence of additional $10\ d$-electrons offer only poor screening effect for the outer electrons from the increased nuclear charge in gallium.

Consequently, the atomic radius of gallium ($135\ pm$) is less than that of aluminium ($143\ pm$).

Ionisation Enthalpy:

The ionisation enthalpy values as expected from the general trends do not decrease smoothly down the group. The decrease from $B$ to $Al$ is associated with increase in size. The observed discontinuity in the ionisation enthalpy values between $Al$ and $Ga$, and between $In$ and $Tl$ are due to inability of $d$- and $f$- electrons, which have low screening effect, to compensate the increase in nuclear charge.

The order of ionisation enthalpies, as expected, is ${\Delta _i}{H_1} < {\Delta _i}{H_2} < {\Delta _i}{H_3}$.

The sequence of $IE_1$ of $13^{th}$ group elements is $B>Al<Ga>In>Tl$.