This "alphabet" also contains "vowels" and "consonants." The chemical elements have for ages been divided into two groups: nonmetals and metals.

   Nonmetals are much less numerous than metals. The ratio between them resembles a basket­ball score - 21 : 83. - also quite like in human speech, which has much fewer vowel than consonant sounds.

   A combination of only vowel sounds inhuman speech rarely expresses anything articulate. It is most often something like a senseless howl. In the chemical language combinations of only "vowels" (nonmetals) are rather common. All life on Earth owes its existence to compounds of the nonmetals with each other.

   Not in vain do scientists call the four main nonmetals - carbon, nitrogen, oxygen, and hydrogen - organogens, meaning substances which give rise to organic life. If we add phosphorus and sulphur, these six "bricks" just about exhaust the list of materials used by nature to build proteins and hydrocarbons, fats and vitamins - in a word, all vital chemical compounds.

   Two nonmetals, namely, oxygen and silicon (two "vowels" of the chemical "alphabet") combine to form a substance written SiO₂ and read silicon dioxide in the language of chemistry. This substance is the ultimate foundation of the Earth's firmament, a kind of cement which keeps all the rocks and minerals from falling apart.
 

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