Detailed chapter Notes - Metal and Non-Metal, Class 10, Science PDF Download

Physical Properties of Metals and Non-Metals - Metals & Non-Metals, Class 10 Science

METALS & NON-METALS

INTRODUCTION
All the materials around us are made up of chemical elements, which are found in the earth's crust. Earth is the source of coal, petroleum, graphite, diamond and many other minerals of metals and non-metals. We get various useful things like gasoline, kerosene, wax, coal gas and natural gas from the natural resources, which are made up of many non-metals. These elements occur as minerals and rocks in the earth's crust. Some of these elements like oxygen, nitrogen and carbondioxide occur in atmospheric air.

There are more than 115 elements known at present 80% of these elements are metals and rest are nonmetals. On the basis of their characteristic properties, all of these elements are divided into two main groups : Metals and non-metals.

POSITION OF METALS AND NON-METALS IN THE PERIODIC TABLE
The elements which are placed on the left hand side (except hydrogen) and in the centre of the periodic table are called metals. Such as sodium, potassium, magnesium, calcium, iron, copper zinc etc.
The elements which are placed on the right hand side of the periodic table are called non-metals such as oxygen, nitrogen, chlorine, fluorine etc. These metals and non-metals are separated from each other in the periodic table by a zig-zag line. The elements placed in the zig-zag line show some properties of metals and some properties of non-metals are called metalloids. Such as boron(B), silicon(Si), germanium(Ge), arsenic(As), antimony(Sb), tellurium(Te) and polonium(Po).

The position of metals, non-metals and metalloids are shown in a simple form in figure..
Metals present at the extreme left are known as light metals, while those are present in the centre of the periodic table are called heavy metals or transition metals.

The elements at the extreme left of the periodic table are most metallic and those on the right are least metallic or non-metallic.

POSITION OF METALS, NON-METALS AND METALLOIDS IN THE PERIODIC TABLE
Thus, metallic character decreases on going from left to right side in the periodic table. For example, sodium
is more metallic than aluminium because sodium is on the left hand side of aluminium.
However on going down in a group the metallic character increases. For example, carbon is non-metal while
lead is metal because metallic character increases down in a group.
 

Metals :
The elements which can be polished, drawn into wires (ductile), hammered into sheets (malleable) and good conductor of heat and electricity are called metals. Such as gold, silver and aluminium. Al is the most abundant metal in the earth's crust.

ELECTRONIC VIEW OF METAL
An element is called metal, which forms positive ions (or cations) by losing electron.
Example : Sodium is a metal which form's sodium ion (Na+) by losing one electron.
Similarly, magnesium metal forms Mg2+ by losing of two electrons, Al metal forms Al3+ by lose of three
electrons.
Thus, metals are also known as electropositive elements.
The atoms of metals have 1 to 3 electrons in their outermost shell. For example, all the alkali metals have one
electron in their outermost shell. (Lithium-2, 1, sodium 2, 8, 1, potassium-2, 8, 8, 1, ... etc).

Sodium₍₁₁₎ magnesium₍₁₂₎ and aluminium₁₃ (2, 8, 3) are metals having 1, 2 and 3 electrons respectively in their outermost shell, which lose these electron easily. The number of electrons lost by an atom of a metal is
called its valency.
Thus metals have 1 to 3 electrons in their valence shell of their atoms.
Exceptions : Hydrogen and Helium. Hydrogen is a non-metal having 1 electron in its outermost shell of its
atom. Helium having 2 electrons in its outermost shell of its atom.

PHYSICAL PROPERTIES OF METALS : The important physical properties of metals are given below :
 

PHYSICAL STATE OF METALS
Most of the metals are solid under normal conditions of temperature and pressure (Except mercury which exist in liquid state at room temperature) For example: Iron, Copper, Aluminium, Zinc, Sodium are solid at room temperature.

HARDNESS OF METALS
Most of the metals are hard, but all metals are not equally hard. The hardness of metals varies from metal to
metal.
For example : Iron, Copper, Aluminium, Sodium and Potassium.

MALLEABILITY OF METALS
The property in which metals can be beaten with a hammer into very thin sheets without breaking is called malleability. Gold and silver are the best malleable metals. Alluminium and copper are also highly malleable metals. All of these metals can be beaten with a hammer to form very thin sheets, are called foil.
 

Activity-1.1
Aim : To show that the metals are malleable.

Procedure : Take a iron nail, a piece of zinc, copper, coal, aluminium, place all of above one by one on a block of iron and strike it 4 and 5 times with a hammer.

Observation :
1. Iron nail, aluminium, copper & zinc metals change their shape into thin sheets.
2. Coal is broken into small pieces. i.e. it is not a metal, because it does not show the property of malleability.

Conclusion :
1.Zinc, Fe, Al, Cu, are malleable i.e. they are metals.
2.Coal is non-metal.

LUSTRE OF METALS
Most of the metals, in their pure state, have a shining surface. This property is called metallic lustre. Example,
gold is shining yellow and copper is brown, iron, aluminium and zinc are lustrous grey.

Activity-1.2 : To show that metals have shine or brightness. Take a small piece of iron, copper, aluminium and magnesium. Now clean their surface by rubbing them with a sand paper.
Observation : Iron is shining grey in colour, magnesium and aluminium appear white, gold in yellow in colour and copper is reddish in colour.

Result : Thus metals have shine or brightness.
 

DUCTILITY OF METALS
Ductility is also an important property of metals. The ability of metals to be drawn (stretched) into thin wire generally, wires are made up of iron, copper and aluminium. Gold and silver are the most ductile metals.

For example 100 mg of silver can be drawn into a thin wire of about 200 metres long. Similarly we can draw a wire of about 2 kilometre from only 1 gm of gold. Copper and aluminium are also very ductile, and therefore, they can be drawn into thin wires which are used in electrical wiring.

We are familiar with silver foil used for decorating sweets and aluminium foil are used for wrapping food.

THERMAL CONDUCTIVITY OF METALS
The process in which a metal allows the flow of heat through it is called its thermal conductivity. Most of metals are good conductors of heat, such as silver, gold, iron, copper and aluminium. Silver and copper are the best conductor of heat.
 

Activity-1.3 :
Aim : To show the metals are good conductor of heat.
Procedure : Take a one metal rod and place it's one end in hot water.
Observation : The other end also gets heated soon.
Result : This shows that metals are good conductors of heat.
 

Activity-1.4 :
Procedure : Take a small wire and clamp it on a stand as shown in figure as below. Then fixed a pin to the free end of the wire with the help of wax. Now heat the copper wire with a candle or burner near its clamped end.

Observation : After some time the other end will also become hot and wax will melt and nail will fall down.

Result : This shows that metals are good conductors of heat. This experiment also shows that metal wire does not melt. i.e. metals have high melting points. Repeat this activity with aluminium & iron metal. Now an important point is arises that "How do metals conduct heat" Metals conduct heat when a portion of an object made of metal is heated, its atoms gain energy. The energetic atoms vibrate vigorously and transfer energy to the other adjacent atoms. In this way the entire object and any thing in its contact also become hot.

ELECTRICAL CONDUCTIVITY OF METALS
The property in which metal facilitates the flow of electric current through it is called electrical conductivity. All metals are good conductors of electricity because they contain free or mobile electrons. These free electrons conduct electric current. Silver is the best conductor of electricity. Since silver is expensive, therefore, copper
and aluminium are commonly used for making electric wires. These metals are next best conductor of electricity.

However, iron and mercury offer greater resistance to the flow of current. Therefore, they have low electrical
conductivities.

Activity-1.5 :
Aim : To show that metal is a good conductor of electricity.
Procedure : Take a dry cell, a bulb fitted in a holder, connecting wires (copper wire), crocodile clips and a switch. Set up all apparatus an electric circuit as shown in figure.

Observation : The bulb glows at once when switch is on.
Result : This shows that copper metal conducts electric current, i.e. it is a good conductor of electricity.
 

SONOROUS 

The property of metals in which metals produce sound when they strike a hard object or other surface are called sonorous. Some metals like copper, silver, gold, aluminium give musical sound when they are struck by
themselves or any other object.

USES OF SOME METALS
Many metals and their compounds are useful in our daily life. These are as follows : Aluminium is used to prepare utensils and house hold equipments like vacum cleaner. Aluminium is extensively used in making bodies of rail, cars, automobiles, trucks and aircraft. Aluminium wires are widely used in electrical work. Aluminium foil is used to wrap chocolate cigarette and medicines and to seal milk bottles.

Major use of copper is in making electrical wires. Copper is also used in making utensils, steam pipes, coin
and in electroplating.

Steel is an alloy of iron which is used for making parts of machines, as building material and in the construction of fridges. As a matter of fact steel is said to be the back bone of industry.

Gold and silver called noble metals (or coinage metals) are used in jewellery.

Mercury is used in thermometers barometers and to prepare amalgams.

Platinum is used to make crucibles and electrodes.

Zinc is used to galvanize iron, to prepare roofing material, container of dry cells and to make brass when
mixed with copper.

Metal like sodium, titanium and zirconium find their applications in atomic energy and space science projects.

Titanium (Ti) and its alloys are used in aerospace, marine equipments, aircraft frames, chemical industries and chemical reactors. The wide application of titanium is attributed to its resistance to corrosion, high melting points and high strength.

The metals such as titanium, chromium, manganese and zirconium are called strategic metals because these metals play an important role in the country's economy and defence. These metals and their alloys are used in high grade steels, jet engines, space science projects and atomic energy.

NON-METALS AND THEIR GENERAL PROPERTIES
Non-metals are present on the right hand side of the periodic table (exception : Hydrogen). Among the total known elements, there are only 22 non-metals, out of which 11 are gases like oxygen, nitrogen, hydrogen one is a liquid (Bromine) and the rest 10 are solids such as sulphur, phosphorus and the allotrops of carbon (Diamond and graphite).

ELECTRONIC VIEW OF NON-METALS
An elements is called non-metal which form ions by gaining electrons. For example, oxygen is a non-metal which form O^2– ions by gaining two electrons. Similarly, nitrogen form N^3– ions by gaining three electrons.
Thus, non-metals also known as electronegative elements.

The atoms of non-metals have usually 4 to 8 electrons in their outer most shell. For example, Carbon (At No. 6), Nitrogen (At. No. 7), Oxygen (At. No. 8), Fluorine (At. No. 9) and Neon (At. No. 10), have respectively 4, 5, 6, 7 and 8 electrons in their outermost shell. However, there are two exceptions namely hydrogen and helium which have one and two electrons in their valence shell or outer most shell, but they are non-metals.

PHYSICAL PROPERTIES OF NON-METALS
The important physical properties of non-metals are given below :
1. Non-metals may be solids, (such as sulphur, phosphorus and diamond), liquid (Bromine), or gases (such as
oxygen, nitrogen, hydrogen, neon, argon, etc.) at room temperature.
2. Non-metals are usually brittle and can not be used to make sheets and wires.
3. Non-metals are non lustrous and can not be polished. (Exception : Graphite and iodine are lustrous nonmetals).

4. Non-metals are generally bad conductor of heat and electricity.
Exception : Graphite which is a good conductor of electricity. Non-metals do not conduct the electric current
due to absent of free or mobile electrons.
5. Non-metals can be easily broken due to its low tensile strength.
6. Non-metals are generally light and have low densities.
7. Unlike metals, non-metals do not produce any sound when struck with an object.
8. Non-metals are soft (Exception : Diamond)
9. Non-metals have low melting and boiling points. (Exception : Graphite has very high melting point (3730°C))
On the basis of the above discussion of the physical properties of metals and non-metals, we have concluded
that elements can not be grouped according to the physical properties alone, as there are many exceptions.

For example,

1. All metals except mercury are solids at room temperature. We know that metals have very high melting points but  gallium (Ga) and caesium (Cs) have very low melting points. These two metals will melt if we keep them on our palm.
2. Iodine is a non-metals but it is lustrous.
3. Alkali metals such as Lithium, Sodium and Potassium are soft, so, that they can be easily cut with a knife. i.e.,  they have low densities and low melting points.
4. Carbon is a non-metal that can exist in different forms. Each form is called an allotrope Diamond, an allotrope  of carbon is the hardest natural substance. which has very high melting and boiling point. Graphite is another  allotrope of carbon which is good conductor of electricity.

The elements can be more clearly classified as metals and non-metals on the basis of their chemical properties.

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Chemical Properties of Metals - Metals and Non Metals, Class 10, Science

CHEMICAL PROPERTIES OF METALS
Reaction of metals with oxygen : Almost all metals combine with oxygen to form metal oxides.
Metal + Oxygen Metal oxide
But all metals do not react with oxygen at the same rate. They show different reactivity towards oxygen. Such
as sodium and potassium react so vigorously that they catch fire if kept in the open. Hence they are kept in
kerosene for protection.

4Na(s) + O₂(g) 2Na₂O
4K(s) + O₂(g) 2K₂O

Sodium and potassium react with oxygen of air, burns with a golden yellow colour and form sodium and
potassium oxides, which dissolve with water to form alkali called sodium hydroxide and potassium hydroxide.

These turn red litmus blue.

Na₂O(s) + H₂O   2NaOH(aq)
K₂O(s) + H₂O 2KOH(aq)
Zinc react with oxygen only when strongly heated to form zinc oxide.
2Zn(s) + O₂(g) 2ZnO
Since, it is less reactive than sodium and potassium.
Copper does not react with oxygen even on strong heating. It react very slowly on prolonged heating to form
cupric oxide (black oxide)

2Cu(s) + O2(g) 2CuO(s)

Similarly, Aluminium forms aluminium oxide.

4Al(s) + 3O2(g) 2Al₂O₃.

At ordinary temperature, the surface of metals like magnesium (Mg), Aluminium (Al), Copper(Cu), Zinc(Zn), lead etc. are covered with a thin layer of oxide. The protective oxide layer prevents the metals from further oxidation. Silver and gold does not react with oxygen due to this silver and gold are called noble metals.

 NATURE OF METALLIC OXIDE
Generally, metallic oxides are basic in nature except aluminium and zinc oxides which are amphoteric in
nature. That means these oxides (Al₂O₃, ZnO) react with base as well as acid. The basic oxide of metals react
with acid to give salt.
For example :
CuO      +        H2SO4            CuSO₄ + H₂O
Copper(II)oxide                              Copper(II) sulphate
Some oxide of metals dissolve in water and form alkalis.
Example for :
Na₂O(s) + H₂O   2NaOH(aq)
                                  Sodium hydroxide
K2O(s) + H2O 2KOH (aq)
                                 Potassium hydroxide

Reaction showing amphoteric in nature of Al₂O₃ and ZnO.
Al₂O₃(s) + 6HCl(aq)                                2AlCl₃(aq) + 3H₂O 

           Hydrochloric acid                                Aluminium chloride
Al2O3(s)            +           2NaOH(aq)                   2NaAlO2(aq) + H2O
                                    Sodium hydroxide(base)           Sodium meta aluminate
Similarly,
ZnO(s) + 2HCl(aq) 2ZnCl₂(aq) + H₂O
Hydrochloric acid Zinc-chloride
ZnO(s) + 2NaOH(aq) Na₂ZnO2(aq) + H₂O
Sodium hydroxide Sodium Zincate

REACTION OF METALS WITH WATER
Metal react with water and produce a metal oxides and hydrogen gas. Metal oxides that are soluble in water
dissolve in it to form metal hydroxide. But all metals do not react with water.
Metal + Water Metal oxide + Hydrogen gas
Metal oxide + Water Metal hydroxide
The following activity clears this reaction properly.

Activity : 1.7 :
Procedure : Take the samples of common metals such as copper, iron, calcium, aluminium, sodium and potassium. Put small of the samples separately in beakers which half-filled with water.
Aim : To study about the reactivity of metals with water & zinc.

Observation : Sodium and Potassium calcium react with cold water. Sodium and Potassium react violently with cold water, making a hissing sound. These reactions are exothermic and evolved hydrogen gas which catches fire and leads to little explosion.
Calcium react less violently and the piece of calcium starts floating in water because the bubbles of hydrogen gas formed stick to the surface of the metal. Now put the metals which do not react with cold water in beaker which is half filled with hot water. Magnesium reacts rapidly with hot water. It also starts flaoting due to the bubbles of hydrogen sticking to its surface. [The rest samples of metals which do not react with cold and hot water.

To study its reactivity with steam, to set up an experiment as shown in figure as below.

A lump of wet glass wool is placed at the bottom of a boiling tube. Then placed the metals samples in the middle of the horizontally kept boiling tube one by one now start at the bottom of a boiling tube with a help of burner. The water present in glass wool forms steam on heating. This steam then pass over the metal. Observe that aluminium react with steam and iron does not react under ordinary conditions but it reacts only when steam is passed over hot iron. Copper do not react with water either at ordinary temperature or at higher temperature. The following reaction occur from the above activity.

1.(i) Na and K metals react vigorously with cold water to form NaOH and H₂ gas is liberated.
2Na(s)     +         2H₂O 2NaOH(aq)         +             H₂(g)
Sodium              Cold water Sodium hydroxide Hydrogen gas
(ii) 2K(s) + 2H₂O 2KOH(aq) + H₂(g)
Potassium cold water Potassium hydroxide
This reaction is so vialent and exothermic that the H2 gas evolved catches fire.

(iii) Calcium reacts with cold water to form Ca(OH)2 and H2 gas. It is less violent.
Ca(s) + 2H2O Ca(OH)2(aq) + H2(g)
                                  Calcium hydroxide

(iv) Aluminium does not react either with cold or hot water. But it react only with steam to form aluminium oxide and hydrogen gas.
2Al(s) + 3H2O(g) Al2O3(s) + 3H₂

              Steam              Aluminium oxide

(v) Similarly, Zinc react with steam to form zinc oxide and H2 gas.
Zn(s) + H2O(g) ZnO(s) + H 2 Steam Zinc oxide

(vi) Magnesium react with hot boiling water to form MgO and H2 gas.
Mg(s) + H₂O MgO(s) + H₂(g)
boiling water Magnesium oxide
(vii) Iron metal react when steam is passed over red hot iron and form iron oxide and H2 gas.
3Fe(s)                +       4H₂O(g)                      Fe₃O₄(s)      +        H₂(g)
Iron (Red hot)             Steam                                     Iron(II, III) oxide
(viii)Copper do not react with even under strong conditions. Similarly, gold and silver also do not react with
water. The above reactions indicates that sodium and potassium are the most reactive metals while copper is
less reactive.

REACTION OF METALS WITH ACIDS
The highly reactive metals react with dilute acid to displace hydrogen from acid. The reactivity of different
metals is different with same acid.

AQUA REGIA (ROYAL WATER)
Aqua regia is a Lattin word it means " royal water". It is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3 : 1. It is a highly corrosive, fuming liquid and it used for dissolve gold and platinium.

REACTION OF METALS WITH SOLUTIONS OF OTHER METAL SALTS
When a more reactive metal is placed in a salt solution of less reactive metal, then the more reactive metal
displaces the less reactive metal from its salt solution . This reaction is also known as displacement reaction.

Activity :
Aim : To compare the reactivity of the metals.
Procedure : Take a clean wire of copper and an iron nail, two test tube. Now dissolve copper sulphate in water in one test tube and ferrous sulphate in another test tube. Place iron nail in the blue coloured copper sulphate solution with the help of a thread and copper wire in the greenish colour ferrous sulphate solution as shown in figure as below.

Observation : The blue colour of copper sulphate has faded and becomes greenish. The green colour of the
solution is due to the formation of iron (II) sulphate and copper is displaced. A reddish-brown coating is
formed on the surface of iron nail. The reaction is represented by the chemical equation.
Fe(s) + CuSO4(aq)  FeSO4(aq) + Cu(s)
Iron Copper sulphate solution Ferrous sulphate
But the greenish colour of FeSO4 do not change. That means no reaction take place.
Conclusion : These activities show that iron metal is more reactive than copper.
Similarly,
Reaction of copper with silver nitrate solution :
When a strip of copper metal is placed in a solution of AgNO3. The solution becomes gradually bule and a
shining coating of silver metal gets deposited on the copper strip. The reaction may be written as :
2AgNO3(aq) + Cu(s)  Cu(NO3)2 + 2Ag
Silver nitrate Copper nitrate Silver
(colourless solution) (blue colour)
However, if we place silver wire in a copper sulphate solution no reaction occurs. This means copper can
displace silver from its salt solution but silver cannot displace copper from its solution. i.e. copper is more
reactive metal than silver.

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The Reactivity Series - Metals and Non Metals, Class 10, Science

The reactivity series :
The arrangment of metals in order of decreasing reactivities is called reactivity series or activity series of
metals. After performing displacement experiments the following series has been developed.

REACTIVITY SERIES OF METALS

in this table the most reactive metal is placed at the above of hydrogen and the less reactive metal is placed below of hydrogen. It may be noted that hydrogen is not a metal but even then it has been placed in the reactivity series. Due to hydrogen can also lose electron and form positive ion (H+)

Reaction of metals with non-metals :
Atoms of elements combine to form stable molecules. The combining power of an atom is expressed as
valency. Each atom has a tendency to attain a completely filled valance shell. The noble gases, which have a
completely filled valence shell or outermost shell, so they are very stable. The electronic configuration of
noble gases and some metals and non-metals are given in the following table.

outermost shell. Which represent a highly stable electronic configuration. Due to this stable configuration,
the noble gases have no any tendency to lose or gain electrons. So they exist monoatomic, sodium atom has
one electron in its outermost shell. If it loses the electon from its M shell the its L shell becomes the outermost
shell. which has stable octet like noble gases. The nucleus of this atom still has 11 protons but the number of
electrons has 10. Therefore, if becomes positively charged sodium ion or cation (Na+).
Na lose 1. electron  Na+ + e–
2, 8, 1 2, 8
Sodium cation
On the other hand chlorine has seven electrons in its outer most shell and it require one more electron to
complete its octet. The nucleus of chlorine atom has 17 protons and the number of electrons become 18.
This makes chloride ion, Cl– as negatively charged
Cl gain 1. electron Cl–
2, 8, 7 2, 8, 8
Chloride ion
So, Na+ and Cl– ions being oppositely charged atoms which attract each other and are held by strong
electrostatic forces of attraction to exist as NaCl. In other words, Na+ and Cl– ions are held together by
electrovalent or ionic bond.

The formation of one more ionic compound magnesium chloride :
The electronic configuration of magnesium (Mg) and chlorine atoms are :
Mg12 : 2, 8, 7
Cl17 : 2, 8, 7
Magnesium atom has two electrons in its valence shell. It has a tendency to lose both of its electrons to attain
the nearest noble gas configuration (i.e. Ne). Mg  Mg2
2,8,7 2,8
.
On the other hand, chlorine has only one electron less than the nearest noble gas (i.e. Ar) configuration. The
magnesium loses its both the valence electrons to two chlorine atoms, each of which is need of one electron
to form Cl– ion.
M g  Mg2+ , Cl  2Cl–
2, 8, 2 2, 8, 7 2, 8, 8

The compounds formed by the transfer of electrons from a metal to a non-metal are known as ionic compound
or electrovalent compounds. The structure of some common ionic compounds are given below :
Structure of some common ionic compounds :

ROPERTIES OF IONIC COMPOUNDS
To learn about the properties of ionic compounds. Let us perform the following activity.
Activity : 1.10 : 1. Take the samples of NaCl, KCl, BaCl2 and CaCl2.
Dissolve small quantity of each solid one by one (a) in water (b) in kerosene and observe.
Observations & conclusion : (a) Each salt is soluble in water. (b) Each salt is insoluble in kerosene. 2. Take small quantity of each salt one by one on a metallic spatula and heat carefully in the top flame of a bunsen burner.

Observations : These salts do not melt on heating in the flame of bunsen burner.
NaCl salt shows yellow colour flame of burner. KCl salt shows violet colour flame, CaCl2 salt shows brick
colour flame and BaCl2 salt shows apple green colour flame of burner.

3. Aim : To show that aqueous solution of ionic compounds conduct electricity.
Procedure : Dissolve a salt (NaCl) in water and make the experimental set up as shown in figure below :

Observations : When the key is pressed it is observed that the bulb glows : Result : This activity shows the current is passing through the circuit as well as through the aqueous solution.

rom the above observations the following general properties are present in the ionic compounds.
Physical state : Ionic compounds are solids and relatively hard because of the strong force of attraction between the positive and negative ions. This attraction of force is also known as strong electrostatic force of attraction. These compounds are generally brittle and break into pieces when pressure is applied.
Solubility : Electrovalent compounds are generally soluble in water and insoluble in solvents such as Kerosene, Petrol, etc.
Melting and boiling points : Ionic compounds have high melting and boiling points, due to the strong electrostatic force of attraction between the oppositely charged ions. Therefore, large amount of energy is needed to break these bonds.

CONDUCTION OF ELECTRICITY
Ionic compounds in the solid state do not conduct electricity because movement of ions in the solid is not
possible due to their rigid structure. But ionic compounds conduct electricity in molten state. In the molten
state, the ions become free and therefore, they conduct electricity due to mobility of ions.

OCCURRENCE OF METALS
The earth's crust is the major source of metals. They are present in nature in the free state as well as in
combined state. Aluminium is the most abundant metal in the earth's crust. The second most abundant metal
is iron and third one is calcium.
NATIVE AND COMBINED STATES OF METALS
Metals occur in the crust of earth in two states : native state and combined state. A metal is said to occur
native or free state when a metal is found in nature in the elementary or in combined form or metallic state.
The metals at the bottom of the activity series are the least reactive. They are often found in a free state.
For example : Gold, Silver, Copper and Platinum are found in free state because they are very unreactive
metals due to they have no tendency to react with oxygen and not attacked by moisture, CO2 of air or other
non-metal. Copper and Silver are also found in the combined state as their suphide or oxide ores.

Distinction between Metals and Non-metals

COMBINED STATE
A metal is said to occur in a combined state if it is found in nature in the form of its compounds.
The very reactive metals which have a tendency to react with moisture, oxygen, sulphur, helogens etc. occur
is the crust of the earth in the form of their compounds. Such as : oxides, sulphides, halides, silicates,
carbonates, nitrates, phosphates etc.
For example : Sodium, Potassium, Calcium, Aluminium, Magnesium etc. are very reactive metals. All of these
are laying at the top of activity series. These are never found in the free state. The metals in the middle of the
activity series such as zinc, iron, lead etc. are moderately reactive. They are found in the earth crust mainly as
oxides, sulphide or carbonates. On the basis of reactivity metals are divided into the following three categories:-

Fig. Activity Series and related metallurgy

MINERALS AND ORES
The natural substances (elements or compounds) in which metals are their compound occur either in native
state ore combined state are called minerals.
For example : Aluminium occur in the earth's crust in the form of two will known mineral, bouxite
(Al2O3, 2H2O) and clay (Al2O3 . 2SiO2 . 2H2O). At some places, minerals may contain a large percentage of
metal where as others may contain only a small percentage of the metal. The mineral from which metal can be
conveniently and profitably extracted, is called an ore. All ores are minerals but all the minerals are not ores.
For example : Copper occurs in nature in the form of several mineral like copper pyrites, copper glance
(Cu2S) and cuprite (Cu2O). But copper can be conveniently extracted from copper pyrites (CuFeS2). Therefore,
ore of copper is copper pyrites. Some common ores ore listed below.

Since, ores of many metals are oxides due to highly reactivity of oxygen and it is very abundant on the earth crust.