INTRODUCTION. Boron, the first member of group 3A, has atomic number 5 and electron configuration ls22s22p1.

Boron, the first member of group 3A, has atomic number 5 and electron configuration ls22s22p1.

At ground state boron, J3 can make only one bond. But in the excited state; it has three half piled orbitals. That's why excited boron, 5B*, can make three bonds.

In contrast to the other members of this group, the element boron generally forms covalently bonded compounds. Boron has a high melting point (2076 °C) because of the strong covalent bonds in its crystalline structure. Boron is found in nature in the form of various crystalline structures.

Pure boron, with a density of 2.46 g/cm3, is quite hard and brittle. It is the second hardest element after the diamond. It melts at approximately 2076°C and boils at 3927 °C. It is a poor conductor of heat and electricity. Nevertheless, since it is a metalloid its electrical conductivity, in contrast to metals, increases with increasing temperature.

The atomic radius of boron is much smaller than others of the same group. Thus its electron affinity is greater. All of these characteristics express the amphoteric property of boron.