It doesn't take much more to complete the list of "vowels" of the chemical "alphabet". All we have to add are the halogens, the rare gases of the zero group (helium, and its brothers) and three not very well known elements, boron, selenium and tellurium.

   However, it would be wrong to say that all living things On Earth are made up only of non­metals. Scientists have detected more than seventy different chemical elements in the human organism: all the nonmetals and a great number of metals, from iron to the radioactive elements, including uranium.

   The reason why there are more consonants than vowels in the human language has long been a point of controversy among linguists. 

   Chemists are interested in why there are two such different groups as nonmetals and metals in the Periodic System. Each of these groups includes elements which differ greatly from one another, but there is nevertheless some resemblance between them.

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