What is Hydrogen atom?

      Position of Hydrogen in the periodic table:

Hydrogen Atom

• Hydrogen is the first element in the periodic table.  Its atomic number is 1 and atomic mass       1.008 a.m.u.  
• The nucleus of the hydrogen atom contains one proton but no neutron. 
• The hydrogen atom has a tendency to lose this electron and change into H+ ion.
• Hydrogen therefore,has an electropositive character like alkali metals.
• The hydrogen atom has also a tendency to gain an electron to complete the 1s subshell and thus has an electonegative character like the halogens.
• Thus in some respects it resembles alkali metals (Group 1) while in some other respects it resembles the halogens (Group 17).
• The points of resemblance and the points of difference of hydrogen with alkali metals on one hand and the halogens of the other hand. 

      Uses of Hydrogen:

• Hydrogen Generators:  The metallic hydrides, such as NaH and LiH, are used in portable hydrogen generators since, when put in water, they release large amounts of hydrogen.  Tin and silicon hydrides have high heats of combustion.  They are being examined as rocker fuels.  The complex borohydrides, such as sodium borohydride, NaBH4, on account of their solubility in organic solvents, are used as reducing agents in a number of organic reaction.
• Hydrogenation Processes:  Hydrogen gas is largely used in hydrogenation processes,that is processes in which hydrogen gas is added as such to compound in the presence of a catalyst.  
• Vegetable oils,such as coconut oil, groundnut oil, which are liquid at ordinary temperatures, are treated with hydrogen at 170⁰C in the presence of finely divided nickel.  They take up hydrogen and change into semi-solid fats which are used as a cooking medium in several countries.
• Carbon monoxide take up hydrogen under pressure in the presence of a catalyst consisting of a mixture of zinc oxide and finely divided copper, to give methyl alcohol.

                                          

• Reducing Agent:  Hydrogen is used in the reduction of metallic oxides in metallurgical processes.  Molybdenum and tungsten, for instance are prepared by the reduction of their oxides by hydrogen.