Chemistry > p Block Elements > 3.0 Compounds of boron
p Block Elements
1.0 Group $13$ – The Boron Family
2.0 Boron
3.0 Compounds of boron
4.0 Compounds of Aluminium
5.0 Group $14$ – The Carbon family
6.0 Allotropes of Carbon
7.0 Compounds of Carbon
8.0 Properties of Silicon
9.0 Group $15$-The Nitrogen Family
10.0 Oxides 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 $N_2O_5$
11.0 Oxyacids of Nitrogen
11.1 Nitric acid $HNO_3$
11.2 Oxidation of Metalloid and Inorganic compounds by Nitric acid
11.3 Action of Metals & Proteins
12.0 Phosphorus
13.0 Oxygen
14.0 Sulphur
3.4 Boron Halides $(BX_3)$
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 $N_2O_5$
11.2 Oxidation of Metalloid and Inorganic compounds by Nitric acid
11.3 Action of Metals & Proteins
Trihalides of boron are planar molecule in which central atom is $sp^2$ hybridized and has an empty $p$-orbital which can accept a pair of electron. Therefore, trihalides are lewis acids.
The B-F bond in BF3 is shorter and stronger than normal B-F single bond due to $p\pi - p\pi $ back bonding which is the main reason for the decrease in acidic strength of $BF_3$.
Preparation:
1. From Boron: $2B + 3C{l_2} \to 2BC{l_3}$
2. From Boron trioxide $(B_2O_3)$: ${B_2}{O_3} + 3Ca{F_2} + 3{H_2}S{O_4}$
Properties:
1. Boron halides are hydrolysed readily by water and product is $H_3BO_3$.
2. Forms adduct with lewis bases e.g., $H_3N$, $H_2S$ etc.
3. Boron halides are lewis acids and acidic strength is: $$BF_3\ <\ BCl_3\ <\ BBr_3\ <\ BI_3$$
