Group 3rd A elements of priodic table.

Group 3^rd A elements of priodic table.

Boron, aluminium, Galium, indium and thallium are the members of group 3^rd A.In this group boron has small size and high nuclear charge. It is the reason that boron has very hig ionization energy. Thus boron is non-metal and other members of group are metals. The abrupt increase in metallic character from boron to aluminium atom.

Occurrence of boron and aluminium:-

                                                                    Boron is not an abundant element. It is found in traces in soil. It is always found in combined form. Its important minerals are given below.

Borax===========>Na₂B₄O₇-10H₂O                                                                                               

Colemanite=======>Ca₂B₆O₁₁-5H₂O                                                                                                                     

Orthoboric=========>H₂BO₃                                        etc.

 Aluminium:-

                        Aluminium is the third most abundant element after oxygen and silicon.its amount in earth,s crust,s is 8.3%. its does not occur in free state. Generally it is found as alumino-silicate minerals.its important minerals are given below.

Bouxite===========>Al₂O₃.2H₂O                                                                                                                                                      

Cryolite==========>Na₃AlF₆

Corundum=========>AL₂O₃

Kaolin (clay)=======>H₂Al₂(SIO₄)₃ OR KalSi₃O₈    etc.

I have mentioned picular behavior of carbon on my another articale you can read from my new site given above on right  side.now we will discus about compounds of boron.

compounds of carbon:-

                                          boron forms a large numbers of compounds.here will explain borax and some boric acidss.

Borax:- 

borax is the sodium salt of tetraboric acid.it is also called “tincal” its chemical name is tetraborate decahydrate. It is found in dry lake area of tibet (china) and california. The coomon name of borax is “suhaga”

Preparation:-

Here is some explanation of preparation of borax.

1)      Borax is prepared by reaction of soda-ash with ho solution of boric acid(H₃BO₃)

        4H₃BOB₃+Na₂CO₃=================èNa₂B₄O₇+6H₂O+CO₂

2)      Borax is prepared by reaction of finely powdered colemanite with boiling solution of Na₂CO₃Ca₂+Na₂CO₃=============è2CaCO₃+Na₂B₄O₇+2NaBO₂(Colimanite)

The  CaCO₃ settles down as precipitate and clear solution of borax and NaBO₂  is taken off. Its crystallization gives fine crystals of borax.we can get more borax by passing CO₂   through mother liquor.

4NaBO₂+CO₂==================èNa₂B₄O₇+Na₂CO_3.
coming next post soon..