| Element | Atomic number | Electronic configuration |
| Boron | 5 | [He]2s22p1 |
| Aluminum | 13 | [Ne]3s23p1 |
| Gallium | 31 | [Ar]3d104s24p1 |
| Indium | 49 | [Kr]4d105s25p1 |
| Thallium | 81 | [Xe]4f145d106s26p1 |
The boron family are the elements in IIIA Group or group 13 of the periodic table, these include boron (B), aluminum (Al), gallium (Ga), indium (In) and thallium (Tl). The Boron family elements are also called as icosagens. These elements are placed in p – block in the periodic table as their outer most or differentiating electron is present in p – orbital.
These elements have ns2np1 valence shell configuration. The boron family have an oxidation states of +3 and +1. All the elements of boron family, expect boron are soft, reactive and are good conductors at moderate temperatures.
Atomic radius and densities tends to increase going down the group. Ionization energy decreases from boron to aluminum and increases from aluminum to gallium due to the poor shielding in outer electron by penultimate shell electrons of Ga. Tl also has an increased I.P to that of indium due to poor shielding by 14f electrons of Tl.
Occurrence of boron family elements:
Boron is a semi–metal. It is a rare element, is not found in free state in nature. It occurs as concentrated deposits
of borax( Na2[B4O5(OH)4].8H2O) and
kernite( Na2[B4O5(OH)4].2H2O).
Aluminum is the most abundant metal and is the third most abundant element in the Earth's. The most important ore of aluminum is bauxite(Al2O3.H2O and Al2O3. 3H2O) .It also occurs in large amounts in aluminosilicate rocks such as feldspars and micas.
- Indium is a silvery white color, soft, lustrous metal and used mainly in mechanical and electronic industries.
- Thallium is a very soft, malleable, lustrous low–melting, silvery metal that tarnishes in air to the bluish–gray oxide.
Gallium is a rare element, it is not found in many minerals. Traces of gallium are found in bauxite and in minerals diaspore (AlO(OH))and germanite (Cu26Fe4Ge4S32).
Indium is rare element with an abundance of 0.000005%(0.05 ppm) in the earth's crust and is the 61st abundant element. Little amounts of it is found in zinc, copper and lead ores.
Thallium is also a rare element and is 56th abundant element in the earth's crust. It exists mostly in association with potassium minerals in clays, soils, and granites. The major source of commercial thallium is the trace amounts found in copper, lead, zinc and other sulfide ores.
Boron family elements show an increase in reactivity going down the group and form compounds such as oxides, hydrides and halides.
Gallium used light emitting diodes(LEDs)
Uses
- Boron compounds are used in organic synthesis,in textile industries, in the manufacture of a special type of glasses and in aerospace structures.
- Aluminum metal is used world wide. It is used in building, transportation and as a structural component in aerospace industry. Because of its high conductivity and low cost it is used in electrical transmission lines.
- Gallium has semiconductor properties, used as light emitting diodes for electronic display and watches. Gallium is used in high temperature thermometers.
- Indium is used as protective plate for bearings and other metal surfaces.
- Thallium is used for making low–melting point special glass for highly reflective lenses. Thallium salts are used as reagents in chemical research.