Occurrence and position of boron and silicon in periodic table

Boron (B) is the first member of group 13 of the periodic table and is the only non-metal of this group. It has an electronic configuration of 1s2 2s2 2p1 with only three electrons in its valence shell.

Dissimilarities of boron with other elements of this group are:

  • Boron is a non-metal while all other elements of this group are metals.
  • Boron forms only covalent compounds, while other elements of this group form both covalent and ionic compounds.
  • Boron shows a maximum covalency of four, while other elements of this group show a maximum valency of six.
  • Boron forms electron-deficient compounds.
These dissimilarities are due to:
  • Small atomic size
  • High ionization energy
  • Low electronegativity.
Boron occurs in the Earth's crust to an extent of about 0.001% mainly as borates and orthoboric acid. The chief minerals of boron are:
  • Borax or tincal Na2[B4O5(OH)4.8H2O
  • Colemanite Ca2[B3O4(OH)3]2.2H2O
  • Kernite Na2[B4O5(OH)4]
Minerals rich in borates are found in California (U.S.A.) and Turkey.

Silicon is present in nature in the form of silica (SiO2) and silicates. Rocks and clays consist of silicate minerals. Silicon is the second most abundant element (~ 27.2 wt%) on the earth's crust after oxygen {45.5wt%}.

1 comment:

rishabh pandey said...

why does silicon dioxide is written as sio2......yet silicon combine with four oxygen atom in tetrahedral manner.......