Elements can be grouped into two broad categories-metals and non-metals. Metals are elements that are Opaque, lustrous, and good conductors of heat and electricity. lron, gold, and silver are common metals.
Non-metals are elements that cannot conduct electricity or heat very well. Examples of non-metals are oxygen, hydrogen, and carbon. Only 18 elements in the periodic table are generally considered non-metals while there are over 80 metals.
Properties of metals
° Metals have lustre. They are shiny when cut, scratched, or polished.
° They are malleable, that is, they can be hammered into thin sheets without breaking.
° They are good conductors of electricity and heat.
° They are ductile, that is, they can be melted and drawn into thin wires.
° All metals except mercury are solid at room temperature.
° Most metals have high melting points.
Properties of non-metals
° Non-metals have no lustre, that is, they have a dull appearance.
° They are poor conductors of heat and electricity.
° They are brittle, that is, they break easily.
° They are neither ductile nor malleable.
° They have low density and low melting points.
Noble metals
Noble metals are pure metals.They are non reactive and do not combine with other elements to form compounds.They donor corrode easily. Noble metals include copper, palladium, silver, platinum and gold. They are ideal for jewellery and coins.
Alkali metals
Alkali metals are very reactive. They have low melting points. They are soft enough to be cut with a knife. Potassium and sodium are two examples of alkali metals.
Application of metals
There are numerous applications of metals. They are used in building, transportation, aerospace technology, computers, and other electronic devices, satellites, and biomedical applications. They are also used in farming and agriculture in tractors, combines, planters, etc. They are commonly used in household appliances such as vacuum cleaners, pumps, water heaters, ovens, dish washers, washing machines, microwaves, refrigerators, etc. Metals are also used for electric power production and distribution. Boilers, turbines, generators, transformers, power lines, nuclear reactors, oil wells, and pipelines
use metals.
Poor metals
Poor metals become useful only when added to other substances poor metals include aluminium, gallium, tin, thallium, antimony, and bismuth.
Metals of antiquity
Metals were discovered around 5,000 years ago. Cold and copper were one of the earliest metals to be discovered. Seven metals, known as metals of antiquity, were metals upon which ancient civilizations were based. These metals were known to the Mesopotamians, Egyptians, Greeks, and the Romans.The seven metals were: gold (6000 BC), copper (4200 BC), silver (4000 BC), lead (3500 BC), tin (1750
BC), iron (1500 BC), and mercury (750 BC).
Metalloids
Metalloids have properties of both metals and non-metals. Some metalloids such as silicon and germanium are semi-conductors.
Alkaline earth metals
Alkaline earth metals are found in compounds with many different minerals. They are less reactive than alkali metals. They are harder and have higher melting points. Calcium, magnesium, and barium are common examples of alkaline earth metals.
Transition metals
Transition elements commonly refer to any element in the d-block of the periodic table. They include zinc, cadmium, and mercury. All transition elements are metals.Therefore, they are also called transition metals.They are hard, shiny strong, and easy to shape. They are used for many industrial purposes.
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