DEFINITION:
Chemical element that, in general,
(2) is opaque but good reflector of light when polished,
All metals crystallize under suitable conditions and (except cesium, gallium, and mercury) are solid at normal temperature. Chemically, metals tend to form positive ions (are electropositive) and most have strong reactive-affinity with certain non-metallic elements (such as chlorine and sulfur) with which they form salts. Trace quantities of some metals (such as cobalt, copper, iron, magnesium, potassium, sodium, and zinc) are essential to animal, human, and plant health.
METAL AND THEIR USES:
Like woods each metal has its especial uses and it will depend largely on what you are going to make as to the kind of metal you should make it of.
There are five chief metals and a couple of alloys, which are formed by melting and mixing two or more metals together, which you will find the most useful and I shall describe these for you in detail.
Iron. - This is the most useful metal we have. When it is pure it has a silvery color, is very tenacious, which means that it is tough; it is malleable, that is it can be hammered without cracking, and it is ductile in that it can be drawn out into wire without breaking.
It is hard to get pure iron for nearly all of it contains a small percent of carbon, silica, phosphorus, sulphur or other elements. These substances in iron give it different properties. For instance cast-iron has a large amount of carbon in it; this kind of iron is good to cast into molds but it cannot be hammered or drawn without danger of cracking or breaking.
Wrought iron has very little carbon or other substances in it and this makes it easy to work because it can be hammered or drawn. Steel contains more carbon than wrought iron but it has less carbon than cast iron; steel can be cast, forged, tempered and hardened by heating it red hot and then suddenly cooling it.
Tin. - This is a white metal that looks very much like silver, and it is so malleable that it can be hammered out into very thin sheets and which you know so well as tin-foil.
It is not found in very many places but the ancients called Britain the Tin Islands because they got it chiefly from there. What we ordinarily call tin is really tin plate, that is thin sheet iron coated with tin, and it is used as a covering for other metals because it does not rust or oxidize in air.
Tin is largely used in making alloys such as soft solder, type-metal, pewter, etc. It has a very low melting point.
Zinc. - This is a bluish white metal and though it is sometimes found in a pure state it is usually found in combination with other elements.
When it is heated to different temperatures it behaves in various ways; for instance when it is cold it is quite brittle, but at 100 to 150 degrees Fahrenheit,17 it can be easily rolled into sheets and rods; curiously though when it is heated to 200 degrees or over it gets brittle again.
Lead. - This is the softest metal known and it has a bluish-gray color. It is very heavy and melts at a low temperature.
17 The Fahrenheit thermometer scale is the one generally used in this country. Fahrenheit was a German scientist who lived 200 years ago, and he invented the mercurial thermometer.
Lead was one of the earliest metals known and if you will read the Book of Job you will find it mentioned there. It has been used from time immemorial in making water-pipes, utensils, etc., and the ancient Romans made weights of it. Since it is so soft it can be easily hammered into any shape or it can be rolled or drawn.
It is also largely used in forming alloys with other metals, thus solder is made of 50 parts of lead and 50 parts of tin; type-metal is made of 80 parts of lead and 20 parts of antimony; and pewter is made of 25 parts of lead and 75 parts of tin.
NON-METAL:
Nonmetal, or non-metal, is a term used in chemistry when classifying the chemical elements. On the basis of their general physical and chemical properties, every element in the periodic table can be termed either a metal or a nonmetal. (A few elements with intermediate properties are referred to as metalloids.)
The elements generally regarded as nonmetals are:
hydrogen (H)
In Group 14: carbon (C)
In Group 15(the pnictogens): nitrogen (N), phosphorus (P)
Several elements in Group 16, the chalcogens: oxygen (O), sulfur (S), selenium (Se)
All elements in Group 17 - the halogens
All elements in Group 18 - the noble gases
There is no rigorous definition for the term "nonmetal" - it covers a general spectrum of behaviour.
The elements generally regarded as nonmetals are:
hydrogen (H)
In Group 14: carbon (C)
In Group 15(the pnictogens): nitrogen (N), phosphorus (P)
Several elements in Group 16, the chalcogens: oxygen (O), sulfur (S), selenium (Se)
All elements in Group 17 - the halogens
All elements in Group 18 - the noble gases
There is no rigorous definition for the term "nonmetal" - it covers a general spectrum of behaviour.
Common properties considered characteristic of a nonmetal include:
#Poor conductors of
#They form acidic oxides (whereas metals generally form basic oxides)
#In solid form, they are dull and brittle, rather than metals which are lustrous,ductile or malleable
#Usually have lower densities than metals
#They have significantly lower melting points and boiling points than metals #Non-metals have high electronegativity .
Only eighteen elements in the periodic table are generally considered nonmetals, compared to over eighty metals, but nonmetals make up most of the crust, atmosphere and oceans of the earth. Bulk tissues of living organisms are composed almost entirely of nonmetals. Most nonmetals are monatomic noble gases or form diatomic molecules in their elemental state, unlike metals which (in their elemental state) do not form molecules at all.
METAL AND WATER QUANTITY:
The metals scan includes calcium, magnesium, and iron which play major roles in water chemistry. Other metals include aluminum, barium, cadmium, chromium, lead, manganese, sodium, and zinc, which tend to be present in smaller amounts. The toxicity of metals is dependent on their solubility and this in turn, depends heavily on pH and on the presence of different types of anions and other cations.
Methodology:
Atomic Absorption Spectrometer analysis has been used in the past to identify these metals. However, in addition to atomic absorption, the laboratory now uses Inductively Coupled Plasma Emission Spectroscopy (ICP).
Environmental Impact:
Metal ions are dissolved in groundwater and surface water when the water comes in contact with rock or soil containing the metals, usually in the form of metal salts. Metals can also enter with discharges from sewage treatment plants, industrial plants, and other sources. The metals most often found in the highest concentrations in natural waters are calcium and magnesium. These are usually associated with the carbonate anion (CO32-) and come from the dissolution of limestone rock. As mentioned under the discussion of hardness, the higher the concentration of these metal ions, the harder the water; however, in some waters other metals can contribute to hardness. Calcium and magnesium are non-toxic and normally absorbed by living organisms more readily than the other metals. Therefore, if the water is hard, the toxicity of a given concentration of a toxic metal is reduced. Conversely, in soft, acidic water the same concentrations of metals may be more toxic.
High pH in a stream can cause precipitation of metal salts which makes them temporarily unavailable. Because of this relationship of toxicity to hardness, Warm Water Aquatic Habitat Criteria for metals are calculated by a rather complex mathematical formula employing the natural log of the hardness. As hardness increases, the allowable concentration increases. The metal criteria in this manual were calculated based on a hardness of 100 mg/L. If the hardness values in the test results vary much from 100 mg/L, the criteria can be recalculated.
Even though metal concentrations may be very low (below a toxic level), aquatic organisms can bioaccumulate (or concentrate) certain metals (for example, mercury, lead, and cadmium). If more is absorbed than excreted, the levels can then build up over time to a toxic level.
When looking at the metals individually, the intended use of the water is very important. Industry requires varying amounts of metals and or hardness for many of its manufacturing techniques, while agriculture has its own requirements.
When looking at the metals individually, the intended use of the water is very important. Industry requires varying amounts of metals and or hardness for many of its manufacturing techniques, while agriculture has its own requirements.
