NON-METALS Boron B. Bromine Br. Carbon C. Chlorine Cl. Fluorine F. Hydrogen H. Iodine I. Nitrogen N. Oxygen O. Phosphorus P. Silicon Si. Sulphur S.
The first step in the building-up process consists of the union of a metallic with a non-metallic element. Such compounds are binary compounds, and are distinguished by the termination -ide added to the name of the non-metallic element; for example, copper and oxygen unite to form copper oxide, sodium and chlorine form sodium chloride, iron and sulphur form iron sulphide or sulphide of iron.
A compound containing more than two elements is distinguished by the termination -ate. Most salts fall within this category; thus we speak of acetate of lead and chlorate of potash, also of sodium sulphate and copper sulphate, the latter form being the more correct.
A difficulty arises when two bodies are composed of the same elements combined in different proportions. Then we have to resort to other distinguishing prefixes or suffixes. For this reason we meet with sulphur_ous_ acid and sulphur_ic_ acid, the corresponding salts being sulph_ites_ and sulph_ates_.
Crystals and Water of Crystallization. When a soluble salt is to be recovered from its solution, the latter is reduced in bulk by evaporation until, either by experience or by trial, it becomes evident that the solid will be formed as the liquid cools. In some cases, when time is not an important factor, evaporation is left to take place naturally. Under either set of conditions, the substance generally separates out in particles which have a definite geometrical form. These are spoken of as crystals.
Crystals often contain a definite percentage of water, called "water of crystallization." In washing soda, this combined water forms nearly 63 per cent. of the total weight; in blue vitriol, it is approximately 36 per cent. On being heated to a moderate temperature, the water is expelled from the solid; the substance which is left behind is called the anhydrous (that is, the waterless) salt.
Key Industries. The importance of the chemical industries depends mainly on the fact that they constitute the first step in a series of operations by which natural products are adapted to our needs. The materials which are found in earth, air, and water are both varied in kind and abundant in quantity, but in their natural state they are not generally available for immediate use. Moreover, very many substances now deemed indispensable are not found ready formed in Nature.