The p Block Elements : Group 15

Modern Periodic Table

The modern periodic table created by Dmitri Mendeleev arranges all the elements known to man in a systematic order. The elements are arranged according to the ascending order of their atomic numbers. Since no two elements have the same atomic number, every element occupies a predetermined spot on the table. Elements with similar electronic configurations exhibit similar properties and are hence categorised into one group. One curious feature of the modern periodic table is, that it is arranged in such a way that you notice a general trend in the properties of elements in one group. In CBSE Class 11 Chemistry, groups 13 and 14 of the p-block of the periodic table were taught to you. Let’s now explore Group 15 – Pnictogens aka Nitrogen group. 

p Block elements: Group 15

Group 15 in the Periodic table consists of 5 naturally available elements and one that has been manufactured by us; namely Nitrogen, Phosphorus, Arsenic, Antimony and Bismuth. The last one is Ununpentium, it is a synthetic superheavy element which has been observed only in the laboratory and it is very unstable. Antimony was the first of the pnictogens to be obtained in elemental form and recognized as an element. The ancient Egyptians used finely ground Antimony Sulphide for eye makeup (kohl). Arsenic has been known to physicians and professional assassins since ancient Greece. Bismuth has a chequered history because scientists kept confusing it with other elements such as lead, tin, and antimony due to similar appearance. It was finally isolated in the 15th century.

Phosphorus was discovered in 1669 by a German alchemist who distilled the pure element out of putrefied human urine. It was named after its unusual property of glowing in the dark (phos= Light, phoros= bringing). Phosphorus occurs in minerals such as Ca9(PO4)6.CaF2 (Fluorapatite) and is also present in bones as well as living cells. Phosphorus was essential to us to make matchsticks, especially during wartime. Despite its abundance, Nitrogen was the last to be obtained in its pure form. It’s a very inert gas and reacts with very few reactants. In the Earth’s crust, it occurs as Sodium Nitrate aka Chile saltpetre (NaNO3) and Potassium Nitrate (KNO3).  About 90% of the Nitrogen produced is used to provide an inert atmosphere for oxygen-sensitive reactions.

Frequently Asked Questions – FAQs


What are group 15 Elements?

Group 15 elements are also called the Nitrogen family including nitrogen phosphorus, arsenic, antimony and bismuth elements. The p-block elements are also known as the Representative Elements which are placed on the right side of the main periodic table.

Why is group 15 called p block?

It is a p-block element since it takes the physical and chemical properties after that of other p-block elements of the eighteenth group. P-block elements are generally non-metals, while the remaining are metalloids and metals.

Why do all group 15 elements have similar chemical properties?

Each element within a group has similar physical or chemical properties because of its atom’s outermost electron shell (most chemical properties are dominated by the orbital location of the outermost electron).

What do we use nitrogen for?

Nitrogen is important to the chemical industry. It is used to make fertilisers, nitric acid, nylon, dyes and explosives. To make these products, nitrogen must first be reacted with hydrogen to produce ammonia.

How are the elements classified into different blocks in the modern periodic table?

The modern periodic table of elements can be broken down into 4 blocks – the s-block, the p-block, the d-block, and the f-block. This classification is based on the types of orbitals that contain the valence electrons of the element. For example, s-block elements have valence electrons in s-orbitals and d-block elements have their valence electrons in d-orbitals.

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