Metals & Non-Metals
Metals
A metal is an element that is malleable and ductile, and
conducts electricity. Some of the examples of Metals are : Iron, Copper,
Aluminium, Zinc, Silver, Gold, Platinum, Chromium, Sodium, Potassium,Magnesium,
Nickel, Cobalt, Tin, Lead, Cadmium, Mercury, Antimony, Tungsten, Manganese and
Uranium.All the metals are solids except one metal mercury, which is a liquid.
 |
| Metals and Non-Metals |
Properties of Metals
The important physical properties of metals are given below
:
1. Metals are Malleable.
This means that metals can
be beaten into thin sheets with a hammer (without breaking). Gold and silver
metals are some of the best malleable metals. Aluminium and copper metals are
also highly malleable metals. All these metals can be beaten with a hammer to
form very thin sheets called Foils. For example, silver metal can be hammered
into thin silver foils because of its high malleability. The Silver foils are
used for decorating sweets. Similarly, aluminium metal is quite malleable and
can be converted Into thin sheets called aluminium foils. Aluminium foils are
used for packing food items like biscuits,Chocolates, medicines, cigarettes,
etc. Milk bottle caps are also made of aluminium foil. Aluminium sheets are
used for making cooking utensils. Copper metal is also highly malleable. So,
copper sheets are used to Make utensils and other containers. Thus,
malleability is an important characteristic property of metals.
2. Metals are Ductile.
This means that metals can
be drawn (or stretched) into thin wires. All the Metals are not equally
ductile. Some are more ductile than the others. Gold and silver are among the
best Ductile metals. For example, just 100 milligrams of a highly ductile metal
like silver can be drawn into a Thin wire about 200 metres long. Copper and
aluminium metals are also very ductile and can be drawn into Thin wires which
are used in electrical wiring. Thus, ductility is another important
characteristic property Of metals. From the above discussion we conclude that
metals are malleable and ductile. It is due to the Properties of malleability
and ductility that metals can be given different shapes to make various
articles.
3. Metals are Good Conductors of Heat and Electricity.
This means that metals allow heat and electricity to pass through
them easily. Metals are generally good conductors of heat (The conduction of
heat is also Called thermal conductivity). Silver metal is the best conductor
of heat.It has the highest thermal conductivity. Copper and aluminium metals
are also very good conductors of heat. The cooking utensils and water Boilers,
etc., are usually made of copper or aluminium metals because They are very good
conductors of heat. The poorest conductor of heat Among the metals is lead.
Mercury metal is also a poor conductor of Heat.
Metals are good conductors of electricity.
The metals offer
very little Resistance to the flow of electric current and hence show high
electrical Conductivity. Silver metal is the best conductor of electricity.
Copper Metal is the next best conductor of electricity followed by gold,
aluminium And tungsten. The electric wires are made of copper and aluminium
Metals because they are very good conductors of electricity. The metals Like
iron and mercury offer comparatively greater resistance to the flow Of current,
so they have lower electrical conductivity.
4. Metals are Lustrous (or Shiny), and can be Polished.
For example, gold, silver and copper are shiny Metals and they can be
polished. The property of a metal of having a shining surface is called
metallic Lustre (chamak). The shiny appearance of metals makes them useful in
making jewellery and decoration Pieces. For example, gold and silver are used
for making jewellery because they are bright and shiny. The Shiny surface of
metals makes them good reflectors of light. Silver metal is an excellent reflector
of light.
5.
Metals are Generally Hard (except sodium and
potassium which are soft metals). Most of the metals are hard. But all the
metals are not equally hard. The hardness varies from metal to metal. Most of
the Metals like iron, copper, aluminium, etc., are very hard. They cannot be
cut with a knife. There are some Exceptions. Sodium and potassium are soft
metals which can be easily cut with a knife.
6. Metals are Usually Strong.
They Have High Tensile Strength. This means that metals can hold Large weights without breaking. For example, iron metal (in the form of steel) is very strong having a high Tensile strength. Due to this iron metal is used in the construction of bridges, buildings, railway lines,girders, machines, vehicles and chains, etc. Though most of the metals are strong but some of the metals are not strong. For example, sodium and potassium metals are not strong. They have low tensile strength. Metals are Solids at the Room Temperature (except mercury which is a liquid metal).
All the metals like iron,
copper, aluminium,silver and gold, etc., are solids at the room temperature.
Only one metal,mercury, is in liquid state at the room temperature.
Metals Generally Have High Melting Points and Boiling Points.
This means that most of the metals melt and vaporise
at high temperatures. For example, iron is a metal having a high melting point of
1535°C. This means that solid iron melts and turns into liquid iron(or molten
iron) on heating to a high temperature of 1535°C. Copper metal has also a high
melting point of 1083°C. There are, however, some exceptions. For example,
sodium and potassium metals have low melting points (of less than 100°C).
Another metal gallium has such a low melting point that it starts melting in
hand (by the heat of our body).
Metals Have High Densities.
This means
that metals are heavy substances. For example, the density of iron metal is 7.8
g/cm3 which is quite high. There are, however, some exceptions. Sodium and
potassium metals have low densities. They are very light metals.
Metals are Sonorous.
This means that
metals make a ringing sound when we strike them. It is due to the property of
sonorousness of metals that they are used for making bells, plate type musical
instruments like cymbals (manjira), and wires (or strings) for stringed musical
instruments such as violin, guitar, sitar and tanpoora, etc.
Metals Usually Have a Silver or Grey Colour (except copper and gold).
Copper has a reddish-brown colour whereas gold
has a yellow colour.Metals are widely used in our daily life for a large number
of purposes. The cooking utensils, electric fans, sewing machines, cars, buses,
trucks, trains, ships and aeroplanes, are all made of metals or mixturesof
metals called alloys. In fact, the list of articles made of metals which we use
in our daily life is unending.
NON-METALS
A non-metal is an element that is neither
malleable nor ductile, and does not conduct electricity.Some of the examples of
non-metals are : Carbon, Sulphur, Phosphorus, Hydrogen,Oxygen,Nitrogen,Fluorine,
Chlorine, Bromine, Iodine, Heliumare also non-metals. They are the allotropic
forms of carbon. All the non-metals are solids or gases, except Bromine which
is a liquid non-metal at room temperature bromine which is a liquid non-metal
at room temperature.
Properties of Non-Metals
The physical properties of non-metals are
just the opposite of the physical properties of metals. The
Important physical properties of non-metals
are given below :
1.
Non-Metals are Not Malleable. Non-Metals are Brittle.
This means that non-metals cannot be beaten Into thin sheets with a hammer.
Non-metals break into small pieces when hammered. For example, sulphur and
phosphorus are solid non-metals which are not malleable, they cannot be beaten
into thin sheets with a hammer. Thus, we cannot get thin sheets from
non-metals. Sulphur and phosphorus non-metals are Brittle. When beaten with a
hammer, they break into small pieces. Brittleness is a characteristic property Of
solid non-metals.
2.
Non-Metals are Not Ductile. This means that
non-metals cannot be drawn into Wires. They are easily snapped on stretching.
For example, sulphur and phosphorus are non-metals and they are not ductile.
When stretched, sulphur and phosphorus Break into pieces and do not form wires.
Thus, we cannot get wires from non-metals.From the above discussion we conclude
that : Non-metals are neither malleable nor Ductile. Non-metals are brittle.
3.
Non-Metals are Bad Conductors of Heat and
Electricity. This means that non-Metals do not allow heat and electricity to
pass through them. For example, sulphur and phosphorus are non-metals which do
not conduct heat or electricity. Many of the Non-metals are, in fact,
insulators. There are, however, some exceptions. A form of the Carbon element,
diamond is a non-metal which is a good conductor of heat. And Another form of
carbon element, graphite is a non-metal which is a good conductor Of
electricity. Being a good conductor of electricity, graphite is used for making
Electrodes (as that in dry cells).
4.
Non-Metals are Not Lustrous (Not Shiny). They
are Dull in Appearance. Non-Metals do not have lustre (chamak) which means that
non-metals do not have a shining Surface. The solid non-metals have a dull
appearance. For example, sulphur and Phosphorus are non-metals which have no
lustre, that is, they do not have a shining Surface. They appear to be dull.
There is, however, an exception. Iodine is a non-Metal having lustrous
appearance. It has a shining surface (like that of metals).
5.
Non-Metals are Generally Soft (except diamond
which is extremely hard non-metal). Most of the Solid non-metals are quite
soft. They can be easily cut with a knife. For example, sulphur and phosphorus
are solid non-metals which are quite soft and can be easily cut with a knife.
Only one non-metal carbon (in the form of diamond) is very hard. In fact,
diamond (which is an allotropic form of carbon) is the hardest Natural
substance known.
6.
Non-Metals are Not Strong. They Have Low Tensile
Strength. This means that non-metals cannot hold large weights (without
breaking). For example, graphite is a non-metal which is not strong. It has a Low
tensile strength. When a large weight is placed on a graphite sheet, it breaks.
7.
Non-Metals may be Solid, Liquid or Gases at the
Room Temperature. Non-metals can exist in all the three physical states :
solid, liquid and gaseous. For example, carbon, sulphur and phosphorus are
solid Non-metals; bromine is a liquid non-metal; whereas hydrogen, oxygen,
nitrogen and chlorine are gaseous Non-metals.
8.
Non-Metals Have Comparatively Low Melting Points
and Boiling Points (except graphite which is a non-metal having a very high
melting point). This means that non-metals melt and vaporise at Comparatively
low temperatures. For example, sulphur is a non-metal having a low melting
point of 119°C.Only one non-metal graphite has a very high melting point (of
3700°C). The majority of non-metals have Very low boiling points due to which
they exist as gases at room temperature.
9.
Non-Metals Have Low Densities. This means that
non-metals are light substances. For example,Sulphur is a solid non-metal
having a low density of 2 g/cm3, which is quite low. The density of gaseous Non-metals
is very, very low. One non-metal iodine has, however, high density.
10.
Non-Metals are Not Sonorous. This means that
solid non-metals do not make a ringing sound When we strike them.
11.
Non-Metals Have Many Different Colours. For
example, sulphur is yellow, phosphorus is white or Red, graphite is black,
chlorine is yellowish-green, bromine is red-brown whereas hydrogen and oxygen
are Colourless.Though non-metals are small in number as compared to Metals, but
they play a very important role in our daily life. In Fact, life would not have
been possible without the presence Of non-metals on the earth. For example,
carbon is one of the Most important non-metals because all the life on this
earth is Based on carbon compounds. This is because the carbon Compounds like
proteins, fats, carbohydrates, vitamins and Enzymes, etc., are essential for
the growth and development of Living organisms. Another non-metal oxygen is
equally important For the existence of life. This is because the presence of
oxygen Gas in air is essential for breathing to maintain life. It is also necessary
for the combustion (or burning) of fuels which provide us energy for various
purposes.
0 Comments