Chemistry of Hydrogen.


Hydrogen is the most abundant element in the Universe. It is the lightest element. It has only one one proton in the nucleus and one electron. It is the only element having no neutrons. The chemistry of this element is given in brief in this article.

Introduction

Hydrogen is the most abundant element in the universe. It is the element with lowest atomic mass. It is a simple element which has only one proton and one electron and no neutrons. It is everywhere in the universe. It is a colorless and odorless gas at room temperature. About 75% of the universe is composed of hydrogen. The stars we see in the sky are nothing but dumps of hydrogen gas only. These produce enormous amounts of energy through the fusion of hydrogen atoms. In smaller stars, hydrogen atoms will colloid and fuse to form helium and other light elements like nitrogen and carbon (essential for life). In the larger stars, fusion products are the lighter and heavier elements like calcium, oxygen, and silicon.

The hydrogen on Earth is mostly found in the form of water only. Hydrogen as an element is only about 0.5 ppm only. This is boon of God to us otherwise hydrogen is very highly flammable and we might have seen hydrogen burning in the atmosphere.

Hydrogen gas forms explosive mixtures with air in concentration between 4 to 74%. and with chlorine in between 5-95%. The reaction can be triggered by a electric spark, heat or sunlight.

  • Atomic number (the number of protons or electrons present in the atom of the element) : 1
  • Atomic symbol : H
  • Atomic weight (the number of protons and neutrons present in the atom of the element) : 1.008
  • Electronic configuration : 1s1
  • Oxidation State (Electrons that can be donated or accepted for stability) - +1 and -1


Elemental classification - Non Metal

The Name hydrogen has come from Greek origin which means water producer. It is first identified in the year 1766 by Mr. Cavendish, a well-known scientist.

Properties

Even though hydrogen is very abundant on earth, very little is found in its elemental form. The reason for this is its low density and very high reactivity. Majority of hydrogen is in water and hydrocarbons.

It is a non-metal. It has the configuration of ns1. This configuration is similar to that of alkali metals. But it has many differences from alkali metals. Hydrogen is placed above these metals in Periodic Table.
Sometimes the hydrogen is placed above halogens in periodic table. But it is very different from halogens also. The ionisation energy is higher than alkali metals. The electron affinity of hydrogen is lesser than that of halogens. Hydrogen reactions are very slow at room temperature due to the strength of H-H bond. It will get activated on heating and reacts with many substances.

Manufacturing Methods

Hydrogen is mainly produced in Industry using two methods.
  • Process 1 - Treatment of methane gas with steam
  • Process 2 - Reaction of coal with steam in the production of water gas.


Isotopes of Hydrogen

There are three isotopes:
  • Protium - It is the main constituent of earthly available hydrogen. The concentration of this isotope in natural hydrogen is about 99.98% The nucleus of this hydrogen contains only one proton.
  • Deuterium - This is another isotope of Hydrogen. The percentage of this isotope in naturally occurring hydrogen is about 0.0156% This is also known as heavy hydrogen and symbol is D. The nucleus of this hydrogen contains one proton and one neutron.
  • Tritium - It is a radioactive isotope of hydrogen. It will have two neutrons in the nucleus. It occurs heavily in upper atmosphere due to cosmic rays. Its half-life is about 12.3 years. It can be produced by bombarding lithium ions with neutrons. This isotope is used in hydrogen bomb It is also used in thermonuclear weapons and experimental fusion reactors.


Uses

  • Mainly hydrogen is consumed in the manufacture of ammonia by Haber process.
  • The second area where it will be consumed is hydro-cracking.
  • Hydrogen is used in hydrogenation reactions.
  • Liquid hydrogen and liquid oxygen are used in combination as rocket fuel.
  • Keeping the depleting stocks of fossil fuels and its effect on environment, lot of studies are going on to use hydrogen as a source of energy. The main advantage in using this as a source of energy the gases come out from burning are mostly gases of oxygen and hydrogen only and no carbon emission in this . So problems of environmental pollution will not be there. All combustion products in hydrogen reactions are green only.


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