metals and Non-metals

Elements can be classified into the following two groups depending on their physical and chemical properties.
metal such as iron, copper, tin, silver and gold. in general, metals are hard and shiny in appearance. non-metal such as Sulphur and Phosphorus. in general ,they are not so hard and dull in appearance.
there are also certain elements, such as Silicon, arsenic, antimony and Germanium, which have some properties of non-metal and some properties of metals. they are known as metalloids.
from the electronic viewpoint, metals are defined as elements which forms positive ions by losing electrons. they contain 1, 2 or 3 Valence Electrons. for example, a sodium atom loses 1 electron, a calcium atom loses 2 electrons and an aluminium atom loses 3 electrons to form the respective positively charged ions.

non-metal are defined as elements which form Negative Ions by gaining electrons. they contain 5, 6, 4,7 Valence Electrons. for example, chlorine contains seven valence electrons and gain one electron to form a negatively -charged ion . oxygen contains 6 valence electrons and gains 2 electrons to form the negatively-charged Oxygen ion .
elements with four valence electrons are normally metalloids. the noble gases with 8 valence electrons do not form ions and cannot really be classified as a metal or non-metal. however, since they are gases they show the physical characteristic of gases.

occurance of metals

In nature, most metal occur in the combined state as minerals. nearly all Rocks contain some metallic minerals. often the amount of metal present in the rock is so little that it is too expensive to mine these Rock and extract the metal from them. if the amount of a metal is more, it is profitable to mine the Rocks and extract the metals. such rocks are called ores. In ores, the useful metallic mineral is mixed with other minerals which are not of much use. these minerals, present as impurities, are called gangue(pronounced as 'gang').
some metals, such as silver, platinum and gold are not very reactive. they occur in the free state in nature. their ores contain particles of metal mixed with large quantities of impurities. they are also known as a noble metals.
the ores of a very reactive metals, such as sodium or calcium, contain chlorides or carbonate of the metals, for example, rock salt (NaCl), dolomite.
the ores of other metals,such as aluminium, iron copper or zinc, contain mostly oxides or sulphides, for example, bauxite ,iron ,pyrites ,haematite, copper glance and zinc blende .
the series of processes carried out to extract pure metals from their Ores is called a metallurgy.

occurrence of a non-metal and metalloids

hydrogen

hydrogen is the most abundant element in the universe- it is the chief element that makes up the sun and the other stars. on earth, hydrogen mainly occurs in combined form as a constituent of water about 11% by a weight of water is hydrogen , petroleum , natural gas,coal, clay and all animal and plants.

nitrogen

nitrogen mainly occur in the free state in the atmosphere. about 76% by mass of air is nitrogen. In the combined state, it is a constituent of minerals such as Chile saltpetre and nitre.

oxygen

oxygen is the most abundant element in the earth's crust. it occurs in the free state in the atmosphere, forming about 23% by of mass of the atmosphere. In the combined state, it constitutes about 89% by a mass of a water. it also present in the combined state in the earth's crust as oxides, carbonates and silicates of metas

carbon

in the free state, carbon occurs as graphite, diamond and coal. diamond and graphite are pure form of carbon. coal containa 60-90% of carbon. in the combined state it occurs in the atmosphere as carbon dioxide. in the earth's crust, it occurs as carbonates of a metal and as the fossil fuels. carbon is the central element of all living matter.

Silicon

Silicon is the second most abundant element in the earth's crust. it does not occur in a free state. in the combined state, it occurs as Silica and silicates. the most common form the silica is sand.

sulphur

sulphur occurs in the free state in the Earth's crust. in the combined state, it occurs in rocks as a metal sulphates and sulphites. it also occurs as a hydrogen sulphide which is present in petroleum and natural gas.
noble gases, such as Helium, neon, argon, krypton and Xenon occur in elemental form in air.
extraction of non-metal from their sources is equally important. non-metals so obtained help in the production of many useful chemicals.

properties of metal and non-metal

physical properties of metal and non-metal

physical state: metals are generally solid at room temperature. mercury is an exception- it is liquid at room temperature. non-metal occur as solid (carbon, sulphur), liquid (bromine) or gases
(oxygen, nitrogen).

lustre: metal have a metallic lustre, they have a Shiny appearance. non-metals do not have a metallic lustre (graphite is an exception)

hardness and strength :metals are generally hard and strong. exception are Sodium,Potassium and magnesium which are soft and can be easily cut with a knife. non-metals are generally not so hard and strong. diamond is an exception. it is the hardest substance known.
Mellebility and ductility: the property of a metal by which they can be beaten into thin sheets is called a malleability.
the property of metal by which they can be drawn into the thin wire is known as the ductility.
non-metal are neither malleable nor ductile; they are brittle.

uses of some metals

uses of iron

pig iron is a hard and brittle form of iron with high carbon content. it is used to make pipes, sinks,Storage tanks, railings, cylinders, etc., by the process of casting.
articles, such as nails, bolts, chains, wire, net agricultural tools, etc., are made by the hammering heated wrought iron. wrought iron is a torch mealleable form of iron with a very little carbon content.

uses of copper

copper is widely used to make electric wires and cables. copper coil are used in several appilances.

it is it is also used to make heating utensils, car radiator and calorimeters.

it form useful alloys.

uses of aluminium

Aluminium is increasingly replacing copper as an electric conductor, especially in overhead cables.

it is used to make cooking utensils.

aluminium foil is used for packing food.

aluminium powder is used as paint to prevent rusting of iron.

uses of zinc

zinc is used in a dry cells.

it is used in a coating iron sheet to prevent rusting of iron. the process is known as the galvanizing of iron.

it is used in the preparation of useful alloys such as brass, bronze and German Silver.

other metals such as lead is mainly used for making electrodes for automobile batteries. it is also used for making alloys such as solder and type metals.

metals and Non-metals