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Metals and Non-Metals - Part II |
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2.
Physical
and chemical properties of metals Metals display the following physical properties : 1.
Metals are malleable : Metals can be hammered or beaten into thin
sheets without breaking. Malleable means that metallic bonds in the metals do not break easily. Gold (Au), silver (Ag) are highly malleable elements. Metals can be made into thin foils
because they are malleable.
2.
Metals are ductile : Metals can be melted and drawn into thin wires.
Because of this property, metals are known as ductile. The ductility
property follows from the malleability property. While being drawn into wires, metals are stretched. Because of the
strong metallic bonds,
the metal atoms do not separate easily. Silver (Ag), copper (Cu), aluminum
(Al) are very ductile, very thin wires can be made out of these elements.
3.
Metals are good conductors of heat and electricity : In metals, the
bonds are formed by excess or free electrons moving around large array of
atoms. These electrons are able to conduct electricity and heat. Silver
(Ag), copper (Cu), aluminum (Al) are good conductors of heat and
electricity. Amongst metals, lead (Pb) is a poor conductor of electricity.
4.
Metals have lustre : Metals generally can be highly polished. The
electronic structure of metals is such that the metals are able to reflect
incident light. This gives metal the characteristic metallic lustre. Gold
(Au), silver (Ag), copper (Cu), platinum (Pt) can be polished and give off a
good lustre.
5.
Metals are highly tensile : Due to their ductility and malleability
properties, metals are very strong. Their bonds do not break easily as the
electrons are shared over an array of metal atoms. This gives metals a very
high tensile strength, and metals do not break easily. 6.
Physical state : Metals are solids at room temperature. Mercury (Hg)
is the only exception - it is liquid at room temperature. Density of metals is
high. Only sodium (Na) and potassium (K) have densities less than water.
Thus all metals are hard materials except sodium and potassium which are
soft metals. Lead is also considered to be a soft metal.
7.
Brittleness : Metals are not brittle. But Zinc (Zn) is an exception.
Metals do not break easily because of their metallic bonds.
8.
Melting and boiling points : All metals, other than sodium (Na) and potassium (K), have high
melting and boiling points. The melting points of sodium (Na) and potassium
(K) are below 100°C.
The melting point of iron is about 1540°C.
9.
Solubility of metals : Pure metals are insoluble in solvents like
water or in any organic solvent. Metals can be dissolved only in acids. 10.
Metals are sonorous : Metals make a characteristic sound when hit with an
object. Thus metals are sonorous. The sonorousness of metals depends on the
temperature and density.
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