Occurrence of Elements

Study Notes

Boron exists naturally as ores such as borax, colemanite, boracite, kernite, tusionite, berborite, and fluoborite.
Aluminum exists as bauxite (Al2O3.2H2O) and aluminosilicate (Al2SiO5) in rocks or clays.
Gallium is found in ores like bauxite, sphalerite, and minerals like diaspore and germanite.
Indium is found in minute quantities in very few indium-containing minerals such as Indite and in zinc, copper, and lead ores.
Thallium is found in many sulphide ores of iron, zinc, and cobalt, and in minerals like crookesite, lorandite, routhierite, and sabatierite.
Nihonium has never been found in nature.

Boron has an abundance of about 0.001% or 10 ppm in the earth's crust.
Aluminum has an abundance of about 8.2% or 82,000 ppm in the earth's crust, making it the third most abundant element.
Gallium has an abundance of about 0.0018% or 18 ppm in the earth's crust.
Indium has an abundance of about 0.000005% or 0.05 ppm in the earth's crust.
Thallium has an abundance of about 0.00006% or 0.6 ppm in the earth's crust.

Boron is a non-metal (metalloid) while the other members of the group are poor metals.
Aluminum is light, the third most abundant element in the earth's crust, and the most abundant metal.
The elements in this group are softer, have lower melting points, and are less conductive than transition metals.
They are fairly reactive in nature and are silvery white.
Aluminum is stable in air due to the formation of an oxide film that protects the metal from attack.

Boron does not react with non-oxidizing acids like HCl, but reacts with strong oxidizing acids like a mixture of hot concentrated tetraoxosulphate (VI) acid and trioxonitrate (V) acid to give boric acid.
The other members of the group react with both oxidizing and non-oxidizing acids to liberate hydrogen gas.
The action of concentrated HNO3 on aluminum and gallium renders them inert or passive by forming a protective layer of oxide on them.

The basicity and reactivity of the elements increase down the group, while the acidity decreases.
The (+1) oxidation state becomes more stable due to the inert pair effect as we move down the group.
The elements exhibit the oxidation state of (+3) which results in the small size of the ions, high charges, and large values for the sum of the first, second, and third ionization energies.
This explains why the elements are largely covalent, as observed in boron and the anhydrous forms of AlCl3 and GaCl3.

The first member of each group on the periodic table exhibits a slightly different property from the other members of the group, known as an anomalous behavior.
This is due to the small size and high electronegativity values of each first member of each group compared to the other members of the group.