Define anomalous behaviou of boran

Like Li and Be, boron – the first member of group 13 – also shows anomalous behavior due to its low size and high nuclear charge/size ratio, high electronegativity and non – availability of d electrons. The main point of differences is:-
1.   Boron is a typical non-metal whereas other members are metals.
2.   Boron is a bad conductor of electricity whereas others are good conductors.
3.   Boron shows allotropy and exists in two forms—crystalline and amorphous. Aluminum is a soft metal and does not exist in different forms.
4.   Like other non metals, the melting point and boiling point of boron are much highr than those of others elements of group 13.
5.   Boron forms only covalent compounds whereas aluminum and other elements of group 13 also do form some ionic compounds.
6.   Hydroxides and oxides of boron are acidic in nature whereas those of others are amphoteric and basic.
7.   The trihalides of boron exist as monomers. On the other hand, aluminium halides exist as dimmers.
8.   The hydrides of boron i.e. boranes are quite stable while those of alumimium are unstable.
9.   Dilute acids have no action on boron. Other members of group 13 liberate h2 from dilute acids.
10.  Borates are more stable than aluminates.
11.  Boron exhibit maximum covalency of four e.g., BH4- ion while other members exhibit a maximum covalency of six e.g.
12.  Boron does not decompose steam while other members do so.