Boron family of elements contains five elements namely boron, aluminum, gallium, indium and thallium. Except boron which is classified as a non metal all other elements of this group are metals. The general electronic configuration of these elements is ns2np1. These elements belong to p block of the periodic table.
The p-block is the most typical amongst all the blocks of the periodic table. It consist of nonmetals, metals and metalloids which exist under normal temperature conditions in all three states of matter, solid or liquid or gas.
Boron Family ElementsBack to Top
These elements do not occur free in nature, rather they are generally found as oxides in many locations around the earth.
Boron Family NameBack to Top
- Increase in atomic size
- Increase in density
- Increase in ionic character
- Decrease in polarity
Among all the members of this family boron is a nonmetal while the rest are metals whose metallic characteristic increases down the group. The non metallic character of boron is due to its small size and high ionization energy.
Atomic Weight of BoronBack to Top
||Atomic weight (amu)
Boron CompoundsBack to Top
The compounds that boron forms are held together by covalent bonds. In covalent bonding valence electrons are shared between atoms. The attraction of each atom on the shared electrons is what binds the atoms together.
Fluoroboric acid is a strong acid and [BF4-] ion is tetrahedral.
Boric AcidBack to Top
By acidifying an aqueous solution of borax with hydrochloric acid or sulfuric acid boric acid is prepared.
Boric Acid Uses
Boric acid is used in
- The manufacture of enamels and glazes for pottery.
- Making heat resisting and shock resisting glass.
- Washing eyes.
Boron NitrideBack to Top
It is prepared by the action of nitrogen or ammonia on boron at 1000oC
Boron Family Periodic TableBack to Top
The members of this family are collectively known as boron family and some times as aluminum family.
Boron Family 3 Valence Electrons
Boron Family FactsBack to Top
- Homburg in 1702 first isolated Boron by distilling borax with green vitriol.
- Boron exist in amorphous and crystalline allotropic forms. The amorphous form is reactive while crystalline form is inert.
- Boron never forms cation and coverts to anion only.
- Boron salicylic acid is an optically active compound.
- Boron is used in making light composite materials for the aircraft.
- Boron is a semiconductor and used in electronic devices.
Boron Family PropertiesBack to Top
The boron family characteristics are discussed below in physical and chemical properties of boron family.
Physical Properties of Boron
- Electronic configuration configuration -There are three electrons in the outer most orbit of each element of this group and that is why their orbit general electronic configuration is ns2np1.
- Atomic and ionic radii -Atomic and ionic radii and atomic volume increase from top to bottom in the group.
- Density -In general on moving down the group the density decreases from B to Tl because increase in size of the atom.
- Melting and boiling point -Melting point do not show a regular trend. Boron has high melting point and it decrease from B to Ga and then increases.
- Oxidation state -A common oxidation state of all these elements is +3 and they exist as M3+ ions.
- Ionization energy and electropositive nature -The ionization energy values of these elements are low as compared to s-block elements of comparable atomic number. These elements are electropositive in nature but less compared to s-block elements. Down the group electropositive character increases.
- Hydration of ions - Only ions of metallic elements get hydrated with six molecules of water and form as octahedral structure.
Chemical Properties of BoronBack to Top
2Al + 2NaOH + 2H2O $\rightarrow$ 2NaAlO2 + 3H2
Boron Family UsesBack to Top
- As a catalyst for polymerization process
- As a reducing agent in organic reactions
- For welding torches
- In high energy fuels and propellants an their combustion leads to a strongly exothermic reaction.
- Boric acid is used as preservative in making potteries, earthen pots and glasses.
- In dying leather and as cleansing and stiffening agent in laundry.
- It is used in borax bead test.
- As a flux in soldering welding and metallurgical processes.