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METAL NON METAL

INTRODUCTION

 

  • You have already studied about elements as being pure substances that each are made up of one kind of atoms only.
  • For convenience of study, these elements are divided into two broad classes: Metals and non-metals.
  • This division of elements is based on the fact that there are certain properties that are found only in metals and certain others that are found only in non-metals.
  • But, there are also some elements that show the properties of both metals and non-metals. They are known as metalloids.
  • Some common metalloids are arsenic, antimony and silicon. The noble (inert) gases from the fourth category of elements.
  • The majority of the elements known to us are metals.
  • For example gold, silver, platinum, copper, iron aluminium, tin, nickel chromium, mercury, calcium, magnesium, lithium, sodium, potassium, zinc, and many more.

METALLOIDS

These elements have characteristics common to metals and non-metals. Example: Arsenic, tin, bismuth etc.

The semimetals or metalloids include silicon and germanium and other elements which possess properties intermediate between those of metals and non-metals. Silicon, for example, possesses a metallic luster, yet it is inefficient conductor and is brittle. The boiling points, melting points, and densities of the metalloids vary widely. The intermediate conductivity of metalloids means they tend to make good semiconductors.

DIFFERENCES IN PHYSICAL PROPERTIES OF METALS AND NON-METALS

 

Metals Non Metals
1.   State: Metals are crystalline solids (except mercury, which is a liquid)

 

2.   Metallic lustre: In their pure state, metals shine. This property is called metallic lustre. In other words, metals can be polished.

 

3.   Density : Metals has high density (except sodium, potassium and lithium)

 

4.   Hardness : Metals and hard solids (except sodium and potassium, which are soft and can be cut with a knife).

 

 

 

5.   Melting point: Metals have high melting points and high boiling points

 

 

 

6.   Malleability : Metals are malleable, i.e., they can be hammered into sheets. Gold, silver, copper, aluminium and tin can be beaten into very thin sheets called foils. (But zinc is brittle, i.e., it breaks into pieces when it is hammered).

 

7.   Ductility : Metals are ductile, i.e., they can be drawn into wires. Gold, silver, copper and aluminium are highly ductile metals, gold being the most ductile of all metals. [Exception : Zinc, arsenic & antimony cannot be drawn into wires].

 

8.   Tensile strength: Metals have high tensile strength, i.e., they can bear a lot of strain [Exception : Zinc].

 

9.   Thermal and electrical conductivity: Metals are good conductors of heat and electricity. Silver is the best conductor of heat and electricity. The poorest metallic  conductor of heat is lead, and the poorest metallic conductors of electricity are iron and mercury.

 

10. Sonority: Metals produce a twangy sound when they are struck with a hard object, i.e., they are sonorous substances.

 

11. Solubility: Metals are usually insoluble in water or inorganic solvents.

Non-metals are either gases or solids [Exception: Bromine is a liquid]

 

Non-metals are dull to look at, i.e., they cannot be polished [Exceptions: Graphite and iodine are lustrous].

 

Non-metals have low density [Exception : Diamond has high density].

 

Non-metals are not hard. If solid they are soft and brittle. For example, phosphorus and sulphur are soft solids and iodine is brittle [Exception : Diamond is the hardest natural substance].

 

Non-metals have both low melting and low boiling points [Exceptions : Carbon, silicon and boron have both high melting and high boiling points].

 

Non-metals are non-malleable. When they are hammered they turn into a powder, i.e., non-metals are of a brittle nature.

 

 

 

Non-metals are not ductile [Exception: Carbon fibre, a recently developed allotrope of carbon, is ductile]

 

 

 

Non-metals have low tensile strength [Exception: Carbon fibre has high tensile strength].

 

Non-metals are band conductors of heat and electricity [Exceptions: Graphite and good conductor of heat and electricity. Gas carbon is a good conductor of electricity].

 

 

 

Solid non-metals do not produce a sound when they are struck, i.e., they are not sonorous substances.

 

With regard to solubility in water or organic solvents there is no fixed rule that applies to the non-metals. For example, chlorine is soluble in water, but sulphur, carbon and phosphorus are not.

 

 

Illustration 1:  Explain the meanings of malleable and ductile.
Solution: i) Metals are malleable, that is, can be hammered (or beaten) in the very thin sheets with a hammer, without breaking.
                   ii)  Metals are ductile, i.e., can be drawn (or stretched) to form thin wire.

 

Illustration 2: Why is sodium kept immersed in kerosene oil?
Solution: Sodium is kept immersed in kerosene oil because on exposure to moist air the surface of sodium is tarnished due to the formation of sodium carbonate layer.
 

CHEMICAL PROPERTIES OR CHARACTERISTICS OF METALS AND
NON-METALS

 

METALS

The chemical properties of the metals are determined by their:

  1. i) Electronic configuration
  2. ii) valency
  3. ii) reducing nature.
  4. i) Electronic configuration of metals: The distribution of electrons in the orbits (energy shells) of the atom of an element is known as the electronic configuration of that atom/element.

A metal has 1 or 2 or 3 electrons in its valence shell. These valence electrons are easily lost during chemical combination.

  1. ii) Valency: Valency refers to the number of electrons that are lost or gained by an atom during chemical combination. Metals have valencies +1  or + 2 or +3. They lose their valence electron during chemical combination to form cations (Positive ions).

 

iii) Reducing nature: Since metals lose their valence electrons, so they are good reducing agents.

  1. Reaction of metals with oxygen
  2. i) In the presence of heat, most metals react with oxygen (or air) to form their respective oxides. These metallic oxides are of a basic nature. Therefore they are known as basic oxides. Basic oxides form salt and water when they react with acids.

Metal + Oxygen  Oxide (basic)

2 Cu + O2  2 CuO (basic oxide)

CuO + H2SO4  CuSO4 (salt) + H2O (water)

 

  1. ii) On the other hand, metals like sodium and potassium react vigorously with oxygen (even in the absence of heat) to form their respective oxides.

Calcium too forms its oxide without being heated. The metallic oxides so formed being soluble in water, they form their respective metallic hydroxides, which are called alkalis. They turn red litmus (an indicator) blue.

E.g.:

 

 

 

 

.

               Note: Alkalis are soluble bases. All alkalis are bases but all bases are not alkalis. This is because all bases are not soluble in water.

iii) Metals like magnesium, aluminium, zinc, iron, lead, copper and mercury react with oxygen on heating to from oxides that are basic in nature but insoluble in water, i.e., they are not alkaline [but magnesium hydroxide is alkaline in nature].

E.g.:

 

 

Metals like silver, gold and platinum do not react with oxygen even on strong heating. Therefore they are called noble metals.

 

  1. Reaction of metals with water

Depending upon their level of reactivity, metals react with water or steam to form their corresponding metallic hydroxides or oxides, along with hydrogen gas.

  1. i) Metals like sodium and potassium react violently with cold water to form their hydroxides as well as hydrogen gas.

The reaction is so vigorous that a fire or an explosion can occur. Calcium too reacts with cold water to from its hydroxide and hydrogen, but the reaction is a moderate one.

Metal + metallic hydroxide + Hydrogen

E.g.:

 

 

  1. ii) Metals like magnesium, aluminium, zinc and iron react with steam to from their respective oxides as well as hydrogen gas.

Metal + Steam  Metal Oxide + Hydrogen

E.g.:

 

Metals like gold, silver, copper and mercury react with neither cold water nor steam.

  1. Reaction of metals with mineral acids.
  • Metals react with dilute hydrochloric acid or dilute sulphuric acid to produce their corresponding salts as well as hydrogen.
  • Nitric acid is not used because, being a strong oxidizing agent, it immediately oxidizes hydrogen to produce water.
  • Sodium and potassium react vigorously with dilute acids, with the liberation of a tremendous amount of heat; magnesium, calcium, zinc and aluminium react only moderately with acids, whereas iron reacts with acids very slowly.

     Salt: A slat is a compound with a metal (or ammonium) ion as its basic radical and a non-metal ion (or a group of non-metallic ions) as its acid radical.

Example:     In sodium chloride, Na+ is the basic radical and C+ the acid radical.

Metal  + Acid (dil)  Salt + Hydrogen

 

 

 

     Note: Lead, copper, silver and gold do not all react with dilute mineral acids.

Metals like Cu, Zn react with concentrated acids.

For example, when Cu react with conc. H2SO4, salt, water an sulphur dioxide gas are produced.

.

 

INDICATORS

  • Indicators are the organic compounds that are used to ascertain the nature of a solution [whether a solution is acidic or basic or neutral].
  • Indicator change colour depending on the nature of the solution in which they are dipped.
  • For example, litmus paper turns blue in basic solution and red in acidic solution.
  • The commonly used indicators are litmus, methyl orange and phenolphthalein.

CHEMICAL PROPERTIES OF NON-METALS

The chemical properties of non-metals are determined by:

  1. i) Electronic configuration.
  2. ii)

iii)      Oxidizing nature.

  1. i) Electronic configuration: Non-metals have 4 or 5 or 6 or 7 electrons in their valence shells. [Exception: Hydrogen and helium are non-metals but they have just one and two electrons in their valence shells respectively].
  2. ii) Valency: Non-metals have valencies –3 or –2 or – 1. They accept electrons in their valence shells to complete their octets, i.e., they form anions during chemical combination.

 

          iii) Oxidising nature: Non-metals tend to gain electrons from metals during chemical combination i.e., they oxidize the metals during chemical combination and themselves get reduced in the process.

Non-metals share electrons during chemical combination with one another as well.

  1. Reaction of non-metals with oxygen
  • Non-metals react with oxygen (air) on heating to form their respective oxides. Most of these oxides are acidic in nature and they turn moist red litmus paper blue.

None – metal + Oxygen  Non-metallic oxide

  1. i) Carbon burns in oxygen to produce carbon dioxide.

 

  1. ii) Sulphur burns in oxygen to produce sulphur dioxide

 

  • Some non-metallic oxides are natural e.g., water (H2O), carbon monoxide (CO), nitric oxide (NO) and nitrous oxide (N2O).

iii) Hydrogen burns in oxygen to produce water, which is a neutral oxide i.e., it does not change the colour of indicators.

.

  1. Reaction of acidic oxides and acids with bases / alkalis
  2. i) Carbon dioxide and sulphur dioxide react with sodium hydroxide to produce the salts sodium carbonate and sodium sulphite respectively, along with water.

Acidic oxide + Base  Salt + Water

 

.

  1. Reaction with water
  2. i) Carbon dioxide dissolves in water and forms carbonic acid.

 

  1. ii) Sulphur dioxide gives sulphurous acid with water.

 

 

  1. Reaction of non-metals with acids
  • Non-metals do not react with dil. HC or H2SO4. But they react with concentrated acids.

Some of the reactions are as follows:

 

 

 

.

METAL REACTIVITY SERIES

The reactivity of metals depends on the ease with which they loose electrons. The metals are placed in increasing order of reactivity into a series called Metal Activity Series.

Metals Activity Series

K > Na > Ca > Mg > Al > Sn > Fe > Sn > Pb [H] Cu > Hg > Ag > Au

Significance of Metal Activity Series

Metal activity series is a series in which

  1. a) the metals are arranged in decreasing order of reactivity.
  2. b) {H} is the demarcating element.
  3. c) metals above {H} can displace H from an acid.
  4. d) metals below {H} cannot displace H from an acid.
  5. e) a more reative metal can displace a less reactive metal from a salt.

Reason for reactivity is that metals higher up in the series loose electrons more easily.

Metals below [H] are found free in nature. Those above [H] are not found free in nature.

  • One the basic of the rate of the reaction of metals with oxygen (air), water and dilute acids, they (the metals) have been arranged in the decreasing order of their chemical reactivity
  • A list in which the metals are arranged in the decreasing order of chemical reactivity is called the metal reactivity series.
  • The most active metal (potassium) is kept at the top of the list and the least active metal (platinum) is at the bottom of the list.

Special features of the activity series:

  1. The ease with which a metal in solution loses electron(s) and forms a positive ion decreases down the series i.e., from potassium to gold.
  2. Hydrogen is included in the activity series because, like metals do, it too loses an electron and becomes positively charged (H+) in most chemical reactions.
  3. If facilitates the comparative study of metals in terms of the degree of their reactivity.

 

The reactivity series of metals
Elements Reaction with oxygen Reaction with water Reaction with acid
1. K

2. Na

3. Ca

React with oxygen at ordinary temperature to form oxides (1, 2 & 3) React with cold water vigorously (1 &2); reacts moderately with water (3) React explosively with dilute acids to give hydrogen (1 & 2); reacts less vigorously (3)
4. Mg

5. Al

6. Zn

7. Fe

Form oxides on heating, but aluminium reacts at ordinary temperature (4, 6 & 7) Reacts with hot water or steam (4); react with steam only to form oxide & hydrogen (5, 6 & 7) React moderately with acid, to produce hydrogen (4, 5, 6 & 7)
8. Pb

9. [H]

10. Cu

11. Hg

Form oxides on very strong heating (8, 10 & 11) No reaction with hot water or steam (8, 10 & 11) Reacts with conc. HCl to give H2(8); do nto react with dilute acids (10 & 11)
12. Ag

13. Pt

14. Au

Do not react with oxygen even on strong heating (12, 13 & 14) No reaction with hot water or steam (12, 13 & 14) Do not react with dilute acids (12, 13 & 14)

 

DISPLACEMNET REACTION

It has been found that a more reactive metal always displaces a less reactive metal from the latter’s slat solution. This can be better understood by the following activities.

 

Some more displacement reactions are as follows:

Zn + CuSO4 ZnZO4 + Cu

[Zn is more reactive than Cu]

Mg + FeSO4  MgSO4 + Fe

[Mg is more reactive than Fe].

 

Illustration 3: Write equation for the reactions of:
                   i)   iron with steam
                   ii)  Calcium and potassium with water
Solution: i)  3Fe(s) + 4H2O(g) ¾® Fe3O4(s) + 4H2(g)
                   ii)  Ca(s) + 2H2O(l) ¾® Ca(OH)2(aq) + H2(g)
                        2K(s) + 2H2O (l) ¾® 2KOH(aq) + H2(g) + Heat energy.

 

Illustration 4:  Samples of four metals A, B, C and D were taken and added to the following solution one by one. The result obtained have been tabulated as follows: 

Metal Iron(II) sulphate Copper (II) sulphate Zinc sulphate Silver nitrate
A No reaction Displacement
B Displacement No reaction
C No reaction No reaction No reaction Displacement
D No reaction No reaction No reaction No reaction

                   Answer the following questions about metals A, B, C and D:

  1. i) Which is the most reactive?
  2. ii) What would you observe when B is added to a solution of copper (II) sulphate?

                   iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.

Solution:     i)   B is the most reactive.

  1. ii) When B is added to a solution of copper (II) sulphate, then B displaces copper from copper sulphate solution.

B get coated with red brown layer of copper and the colour of copper sulphate solution fades.

iii) B > A > C > D

 

Illustration 5: Which gas is produced when dilute hydrochloric acid is added to reactive metal? Write a chemical reaction when iron reacts with dilute H2SO4.
Solution: Hydrogen gas is produced when dilute hydrochloric acid is added to a reactive metal.
  Fe(s) + H2SO4(aq) ¾® FeSO4(aq) + H2(g)

 

 

Illustration 6: What would you observe when zinc is added to a solution of iron (II) sulphate? Write the chemical reaction that takes place.
Solution: Zinc displaces iron from iron (II) sulphate solution to form zinc sulphate and ion metal.
 

 

ELECTRON REDISTRIBUTION IN CHEMICAL BONDS

Chemical Bonds can be classified in a very broad way based on whether electrons are transferred or shared into

  1. a) IONIC BOND and
  2. b) COVALENT BONDS.
  3. a) Ionic Bonds or Electrovalent Bond

An Ionic Bond is a chemical bond formed between two atoms (usually a metal and a non-metal) by transfer of electrons from valence shell or one atom to valence shell of another atom.

The transfer of electron takes place in such a way that both the atoms attain inert gas configurations.

The actual bond is formed due to electrostatic force of attraction between the resulting two oppositely charged ions.

Example : Ionic bond formation in NaCl

Consider Na and Cl atoms

Na has a configuration (2, 8, 1), it has a tendency to loose one electron (oxidation)to form Na+ ion. On loosing the electron the Na+ ion that is formed has the stable configuration of Neon-an inert gas. Hence the ion of sodium is more stable than the atom of sodium. This is also the reason why sodium does not occur in the free state as sodium but occurs as compounds of sodium only.

Cl has a configuration (2, 8, 7). It has a tendency to accept one electron (reduction) to form Cl ion. On gaining one electron the Cl ion. On gaining one electron the Cl ion that is formed has the stable configuration of Argon-an inert gas. Hence the ion of Chlorine is more stable than the atom of chlorine. This is also the reason why chlorine will not occur in the free state but occurs as compounds of chlorine only.

The actual bond is formed by attraction of Na+ ion and Cl ion – opposite ions attract each other.

Other examples:

    Cation formation configuration changes Anion formation configuration changes Ionic bond formation
1 Ion formation K – 1e ® K+
(2, 8, 8, 1)® (2, 8, 8,- Argon)
Cl + 1e ® Cl
(2, 8, 7)® (2, 8, 8 – Argon)
K+ + Cl ® KCl
2 Ion formation Mg – 2e ® Mg2+
(2, 8, 2) ® (2, 8 – Neon)
O + 2e ® O2–
(2, 6 ® (2, 8 – Neon)
Mg2+ + O2– ® MgO
3 Ion formation 2Al – 6e ® 2Al3+
(2, 8, 3) ® (2, 8 – Neon)
3O + 6e ® 3O2–
(2, 6) ® (2, 8 – Neon)
2Al3+ + 3O2– ® Al2O3
4 Ion formation Ca – 2e ® Ca2+
(2, 8, 8, 2) ® (2, 8, 8– Argon)
2Cl + 2e ® 2Cl
(2, 8, 7) ® (2, 8, 8 –Argon)
Ca2+ + 2Cl ® CaCl2

Covalent Bond, 1916, Lewis (America)

Sharing of electrons such that each atom donates an electron to the shared pair forms Covalent Bonds. On sharing both atoms get either a duplet or octet configuration. They are also known as Atomic Bond or Electron Pair Bond.

Lewis Dot diagram

To denote the valence shell electrons, dots or crosses around the symbol of the atom are used. This is called Lewis diagram. It is used to represent the bond formation between atoms.

Examples: H2, Cl2, HCl, N2, O2, F2, H2O, NH3, CO2, CH4

H2 molecule : or H – H or H2
Cl2 molecule : or Cl – Cl or Cl2
HCl molecule : or H – Cl or HCl
N2 molecule : or N º N or N2
H­2O molecule : or H2O
CO2 molecule :   or CO2
NH3 molecule : or NH3

Based on covalency

Covalency is the number of shared PAIRS of electrons between atoms in a covalent bond.

It is never greater than 3

Single Covalent Bond molecules have one shared pair of electrons. Their Covalency is 1. Eg.: H2, Cl2 etc.

Double Covalent Bond molecules have two shared pairs of electrons. Their covalency is 2. Eg. : O2

Triple Covalent Bond molecules have three shared pairs of electrons. Their covalency is 3. Eg. : N2.

USES OF SOME COMMON METALS

Copper  

  • Copper was among the first metals discovered by man along with gold and silver. It is reddish brown in colour.
  • It is highly ductile , i.e., capable of being drawn into wires, and also a very good conductor of heat and electricity.

It is used in making:

  1. i) electric wires and cables, utensils and semi-precious ornaments.
  2. ii) coins and statues (in the form of its two alloys, brass and bronze).

iii) electronic devices.

  1. iv) several electroplating operations.
  • The use of copper in the electrical goods industry has declined due to the increasing use of aluminium as its substitute. Also copper is costly.
  • But the most important reason from its decline is its scarcity.

 

Iron

  • Iron is definitely the most useful of all metals. It is among the most ancient metals known to man.
  • There are three different varieties of manufactured iron, depending mainly on the proportion of carbon present in it.

 

These are:

  1. a) pig iron (or cast iron)
  2. b) wrought iron
  3. c) steel

 

  • Wrought iron is the purest form of iron, since it has the least proportion of carbon present in it, while pig iron is the most impure form of iron, since it has the highest proportion of carbon present in it.
  • Steel is the most widely used form of impure iron, to the extent of being the very basis of modern life.

 

Iron is used in the manufacture of:

  1. i) radiators, railings, manhole lids, drain pipes [in the form of pig iron].
  2. ii) tanks, cylinders, smaller pipes, agricultural tools, nails and bolts, furniture, gates, etc. [in the form of wrought iron].

iii)      bridges, ships, machine parts, automobiles, buildings and utensils [in the form of steel].

  1. iv) power transmission towers.

Aluminium

  • Aluminium is definitely the second most useful metal today, after iron.
  • It is silvery white in colour, malleable, ductile, light and strong, and it is a vbery good conductor of heat and electricity as well.
  • Also it is resistant to corrosion. Therefore aluminium finds widerange applications.

          It is used

  1. i) to make utensils, cans for drinks, furniture, window frames, etc.
  2. ii) in making electric wires.

iii) for packaging of foodstuffs (in the form of aluminium foil).

  1. iv) as a paint ingredient (in the form of its powder mixed with linseed oil, which protects against rusting when applied to the surface of iron).
  2. v) to make the bodies of aircraft and automobiles, and a machine parts and tools. This is because, in the form of its alloys duralumin and magnallium, it is light and very strong.
  3. vi) in making mirrors (as reflector material).
  • Cheap and abundant power is a must for the extraction of aluminium from its ore.
  • Therefore, aluminium plants are located near big hydropower stations.

 

Zinc

  • Zinc is a bluish white metal. It is neither malleable nor ductile, rather it is brittle. It is a good conductor of electricity.

Zinc is used

  1. i) to make dry cells and electrodes.
  2. ii) to make alloys like brass and bronze that are used to make utensils, statues, decoration pieces, etc.

iii) to coat (galvanization) iron sheets so as to prevent them from rusting.

  1. iv) in the extraction of silver and gold from their ores.

Lead

  • Lead is a heavy, silver grey metal. It stays unaffected by impure water, steam and dilute acids.
  • It has low melting point.

 

          It is used for:

  1. i) making pipes and other sanitary fittings, bullet tips and tin roofs.
  2. ii) covering underground electric and telephone cables.

iii) making solder and type metal.

  1. iv) the preparation of compounds like lead sulphate, red lead and litharge, which are used in paint and emulsion products.
  2. v) making screens that protect against X-rays and other radioactive radiations.

Magnesium

  • Magnesium is a silvery white metal. It is available in the shape of ribbons.

          It is used:

  1. i) in preparing fireworks, since it burns with a dazzling light.
  2. ii) in the preparation of alloys like duralumin and magnallium.

iii) for making fuse wire.

  1. iv) in nuclear reactors for the absorption of neutrons.

Tin

  • Tin is a silvery white metal. It is highly malleable and ductile. It does not rust.

          It is used:

  1. i) to make cans for storage of foodstuffs.
  2. ii) for coating of utensils made of other metals so as to prevent them from corroding.

 

Calcium

  • Calcium is a white lustrous metal that slowly dulls down on exposure to air.
  • It rarely occurs in free state, but in combined state it is found in the earth’s crust as phosphates, sulphates, carbonates, etc.
  • The sulphate and chloride salts of calcium are present in hard water.

 

In its various combined states, calcium has wide applications

  1. i) Calcium chloride is used as a drying agent, i.e., for physical removal of water.
  2. ii) Calcium carbonate is used in the manufacture of glass, cement, lime, washing soda etc.

iii)      Marble, a non-crystalline form of calcium carbonate, is used for building and laboratory purposes. It is used also to make statues.

  1. iv) Chalk, another form of calcium carbonate, is used for distempering of walls, in toothpastes and talcum powder, and in medicines for indigestion etc.

Gold:

  • Gold is a shiny yellow metal. It is extremely precious owing to its beauty, scarcity and chemical and physical stability.
  • Gold is highly malleable and it is resistant to corrosion. It is a very good conductor of heat and electricity as well.

          Therefore it is used in

  1. i) the manufacture of electronic devices like telephones, computers, etc.
  2. ii) making ornaments and coins.

iii) dentistry to fill into teeth cavities (in the form of amalgam, an alloy made of gold, silver and mercury).

Silver

  • Silver is an half white, lustrous metal. It is the most ductile metal known to man.
  • It is also the best known of all metallic conductors of electricity.

It is used

  1. i) for making jewellery, since it is fairly scarce and therefore semi-precious.
  2. ii) for filling into teeth cavities (in the form of amalgam, an alloy made of gold, silver and mercury).

iii) as a water purifier

  1. iv) for making electrodes and in several electroplating operations.
  2. v) in photography (in the form of silver nitrate and silver bromide).
  3. vi) in the form of silver iodide to seed clouds in order to crate “artificial rain”.

Though silver is the best known metallic conductor of electricity and the most ductile metal, it is not used for making electric wires. This is because it is rather costly and not a chemically stable as is required for transmission of electricity.

Mercury

  • Mercury is a silvery white, liquid metal. It does not moisten glass and it expands a lost on heating.

          Therefore it is used in

  1. i) thermometers (as thermometric liquid):
  2. ii) barometers and other scientific apparatus.

iii) dentistry, for filling into teeth cavities in the form of alloys known as silver amalgam and gold amalgam.

Platinum

  • Platinum is a lustrous and a very precious metal. It is not reactive, just as is god, Platinum is an excellent catalyst.

          It is used

  1. i) for making electrodes and electrolytic cells.
  2. ii) for making expensive ornaments and watches.

THE NEED TO RECYCLE AND CONSERVE METALS

  • Learning the art of isolating the metals from their corresponding minerals was a big step forward for human civilization.
  • Metals find application in almost every field. They are used in utensils, buildings, factories, agricultural equipment, medical equipment, automobiles, locomotives, navigation, aviation and warfare machinery, space programmes and in many other fields.
  • However, it has been observed that metal objects become dull with passage of time.
  • Iron articles get covered with a brown coating, called rust. Aluminimum vessels become a dull grey.
  • Copperware lose their shine and acquire a green coating, and silver ornaments turn black.
  • This causes economic loss because metals that lose their properties are rendered unfit for further use.

The wasting away of a metal layer by layer is called corrosion. The damage of metals by corrosion causes heavy economic loss. Therefore, it becomes necessary to protect  the metals from corrosion and thus conserve them.

  • Metals are prevented from being corroded by applying one or more or the following methods.
  1. Painting:

This is the most common method employed to protect metals. Steel, furniture, iron bridges, railway coaches, machines and the bodies of buses and trucks are coated with paints (make usually from lead or zinc). The layer of paint acts as a shield against corrosion.

  1. Greasing or oiling:

Greasing or oiling of metal articles protects them from corrosion by shielding them from direct contact with air and moisture.

  1. Galvanisation:

The process of coating iron articles with a thin layer of zinc is known as galvanisation. Zinc subsequently changes to zinc oxide, which prevents the contact to iron with air and moisture.

  1. Electroplating:

In this process, the surface of metal to be protected is coated with a layer of another metal by electrolysis. In the case of gold, the process is known as gilding or gold plating.

Metal articles that have become completely useless can be retreated with chemical reagents to       regain them in their pure and usable forms.

 

USES OF SOME COMMON NON –METALS

  • None-metals too play a vital role in everyday life.
  • Proteins, carbohydrates and fats are made mostly of the non-metals carbon, hydrogen, oxygen and nitrogen.
  • We need oxygen to breathe and plants need carbon dioxide for photosynthesis.
  • Non-metals are also important for the manufacture of a number of industrial substances.

 

The uses of some commonly known non-metals are discussed below:—

Oxygen

  • Oxygen is a life-supporting gaseous non-metal. No living thing can survive without oxygen.
  • About 21% by volume and 23% by weight of air is oxygen 88.8% of pure water by weight is oxygen.
  • In combined state, it is present in the earth’s crust as oxides, carbonates, sulphates, etc.

Oxygen is used

  1. i) For respiration and combustion.
  2. ii) For artificial respiration for patients suffering from breathing problems (in the form of carbogen, a mixture of 95% oxygen and 5% carbon dioxide).

iii)      For artificial respiration by people in special occupations. Deep sea divers, mountaineers, astronauts, miners and firemen carry oxygen cylinders with them.

  1. iv) To weld and cut metals.
  2. v) In the extraction of iron and manufacture of steel. Oxygen reacts with the impurities of the crude iron ores to form ferrous oxides.
  3. vi) In the manufacture of sulphuric and nitric acids.

vii)     For blasting of rocks in the mining industry; carbon dust (carbon mixed with liquid oxygen) is used as an explosive, a substitute for dynamite.

viii)    As a propellant for spacecraft; liquid oxygen (LOX) helps to burn hydrogen. Oxygen is carried in containers attached to the spaceships since, in space, there is no oxygen.

 

Nitrogen

  • Nitrogen constitutes about 78% of air by volume. It is a colourless, odourless, tasteless gas.
  • It is slightly lighter than air. It is neither combustible nor supporter of combustion.
  • Nitrogen is an important component of human food nutrients.
  1. i) Nitrogen plays an important role in controlling the rate of combustion. It dilutes the oxygen present in the air that we breathe, otherwise, pure oxygen would burn our lungs.
  2. ii) It is an important constituent of proteins, which are necessary for the growth of animals, plants and human beings. Plants convert nitrogen into proteins.

iii)      It is used in the manufacture of compounds like ammonia and nitric acid.

  1. iv) It is used to make fertilizers like ammonium salts, urea, potassium nitrate, etc.
  2. v) It is used to prepare explosives like T.N.T. (Trinitron toluene)
  3. vi) Because of its inert nature, nitrogen is used for preservation of food. The containers used for storing foodstuffs are flushed with nitrogen (to remove oxygen) before they are packed and sealed. The absence of oxygen does not allow for bacterial growth. Thus food remains fresh for a long time.

 

During a thunderstorm, when lightning occurs, nitrogen and oxygen in the atmosphere combine to form oxides of nitrogen, which are washed away with rain (in the form of nitric acid) into the soil.

 

Chlorine

  • It is a greenish yellow gas, with a pungent, suffocating smell. It is fairly soluble in water, forming a pale yellow solution called chlorine water.

Chlorine is used

  1. i) As a bleaching agent for rough and hand fibers like jute and cotton.
  2. ii) As a disinfectant for sterilizing both drinking water and swimming pool water.

iii)      In the manufacture of mineral acids like hydrogen chloride.

  1. iv) In the manufacture of chemicals like D.D.T. (Dichloro diphenyl trichloro ethane), B.H.C (Benzene hexachloride) and bleaching powder (CaOCl2), which are used as an insecticide, a pesticide and a disinfectant, respectively.

 

                                                                                        

Sulphur                                                                                       

  • Sulphur is yellow solid. It is brittle in nature. In free state in occurs in volcanic regions, while in combined state it occurs as sulphates, sulphides, etc.
  • Substances like garlic, onion, eggs, hair and wool contain sulphur. Sulphur in small amounts is a vital ingredient for the human body.

 

Sulphur has wide applications

  1. i) It is used in the chemical industry for the manufacture of sulphuric acid, sodium thiosulphate (used in photography), gunpowder, dyes, matches and fireworks.
  2. ii) It is used in the medical industry:
  • to prepare skin ointments, since it has excellent fungicidal properties.
  • to fumigate disease-infected areas (in the form of sulphur vapour)
  • to purify blood (in the form of a colloidal solution).
  • to prepare homeopathic and ayurvedic medicines.
  • to prepare a range of other medicinal drugs.

iii)      Sulphur powder is used as an insecticide and as a fungicide.

  1. iv) In the form of sulphur dioxide it is used for fumigation of factories, godowns and cold storages.

Phosphorus                                                                               

  • Phosphorus is found in red or yellow or white or black or scarlet colours. It does not occur in free state, since it readily combines with oxygen.
  • In combined state phosphorus occurs as phosphates. It is present in the brain, the bones and the teeth of animals [in the form of calcium phosphate [Ca3(PO4)2] and in plant cells.
  1. i) White phosphorus is used as rate poison. It is used also in fireworks because of its inflammable nature.
  2. ii) Phosphorus is used in the manufacture of fertilizers, detergents and fine chinaware.

iii)      Phosphorus sulphide is used on the sides of safety match boxes.

Silicon

  • Silicon is one of the most useful elements available to modern man. It does not occur free in nature.
  • In combined state however it ranks next only to oxygen in abundance i.e., as sand. [The chemical name of sand is silica (SiO2)].
  1. i) Highly purified silicon is used in making microchips for computers, transistors, solar cells, rectifiers and other solid state devices that are used extensively in the electronic and the space age industries.
  2. ii) Silicon is used in the manufacture of “silicone”, a waterproof material.

iii)      It is used also to prepare silicon carbide, which is the hardest substance prepared by man. It is used as the grinding agent in various kinds of grinding tools.

  1. iv) In the form of sand to prepare concrete, bricks and cement. Sand is the principal ingredient of glass.
  2. v) In the form of silicates, silicon is used in enamel, pottery, etc., and for preserving eggs.
  3. vi) Silicon is an important ingredient in steel, an alloy of iron.

Iodine

  • Iodine is a dark grey, crystalline solid, with a metallic lustre. It is insoluble in water but soluble in water but soluble in both alcohol and potassium iodide solutions.

It is used

  1. i) In the form of iodized slat for the healthy growth of the human body. Iodine deficiency causes goiter and other thyroid based diseases.
  2. ii) In Photographic films (in the form of potassium iodide).

iii)      to make tincture of iodine and iodex, which are used as disinfectant and pain reliever respectively.

Fluorine

  • Pure fluorine is a greenish yellow gas with a suffocating odour.
  1. i) Fluorine is used mainly in the production of fluorides and fluorocarbon compounds.
  2. ii) In the form of stannous fluoride it is used in toothpastes to prevent dental decay, especially in children.

iii)      Fluorine is used to prepare a type of plastic known as teflon. Teflon is thermally stable and chemically resistant. Therefore, it is widely used as an insulator and as a lubricant.

  1. iv) Fluorine is potentially a rocket fuel, through it is rarely used for this purpose.

 

Illustration 7:  A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
Solution:     The solution he has used may be aquaregia which is 3 parts of conc. HCl and 1 part of HNO3. It can dissolve noble metals such as gold.
Aqua-regia dissolved a considerable amount of gold bangles and hence reduce their weight drastically. The man can recover the dissolved gold from aqua-regia by a suitable treatment.

 

 

Illustration 8: Give the reason why copper is used to make hot water tanks but steel (an alloy of iron) is not.
Solution: Copper is used to make hot water tanks because it is an extremely good conductor of heat.

 

 

ALLOYS AND THEIR USES

  • This word ‘alloy’ comes from the French word “alloyer”, meaning ‘to bind’.
  • An alloy is a solid mixture of usually two or more metals homogeneously fused together from their molten state.
  • The properties of an alloy are different from the properties of the metals of which it is made.

Amalgam:

An amalgam is an alloy is which one of the component metals is mercury.

Purpose of making alloys

  1. To prevent corrosion.
  2. To acquire metallic substances of attractive colours.
  3. To acquire metallic substances that have a desirable melting point.
  4. To harden or strengthen or lighten the metal. Pure gold is so soft that is cannot be used for making ornaments. When mixed with copper or brass, however, gold is hardened enough for use as ornament material.

Note: The science and the art of making alloys was known to the ancient Indians. Ashtadhatu and panchadhatu are to alloys mentioned in historical books.

 

Alloys, their compositions, properties and uses
Alloys of copper Composition Properties Uses
1. Brass Cu – 60–70%

Zn – 30–40%

Lustrous, more malleable and ductile than copper; much harder than copper; can be easily cast; resists corrosion. For making status, screws and handles, utensils, machine parts and decorative articles.
2. Bronoze Cu – 80%

Zn – 2%

Zn – 18%

Hard and brittle; resistant to corrosion; takes up a high polish. For making coins and medals, utensils and status.
3. Bell metal Cu – 80%

Sn – 20%

Sonorous (produces a sound); hard hand brittle. For making bells and gongs, statues etc.
4. German silver Cu – 50%

Zn – 30%

Ni – 20%

White and bright like silver; malleable and ductile; high electrical resistance. For making ornaments, decorative articles, heaters and rheostats etc.
5. Gun metal Cu – 88%

Sn – 10%

Zn –1%

Pb – 1%

Hard and brittle and can be easily cast. For making gun barrels and cannons, gears and motor brushes.
Alloys of aluminium    
1. Duralumin A – 95%

Cu – 4%

Mg – 0–5%

Mn – 0-5%

Light but as strong as steel; hard and resistant to corrosion; highly ductile. For making aircraft bodies, light tools, pressure cookers.
2. Magnalium A – 90-95%

Mg – 8-10%

Very light and hard; resistant to corrosion. For making light tools, beam balances and machine parts
3. Alnico A – 20%

Fe – 50%

Ni – 20%

CO – 10%

Highly ferromagnetic in nature. For making powerful magnets.
4. Aluminium Bronze A – 9.5 %

Cu – 90%

Sn – 0.5%

Easily moulded; Resistant to corrosion; Golden yellow in colour For making artificial jewellery; coins; pictures frames.
Alloys of Lead    
1. Solder Pb – 50%

Sn – 50%

Low melting point For soldering of joints and fusing of metal objects.
2. Type metal Pb – 75%

Sb – 20%

Sn – 5%

Low melting point; expands and can be cast easily. In the printing industry.
Alloys of steel    
1. Stainless steel Fe – 75%

Ce – 15%

Ni – 8-9%

C – 0.5-1%

Lustrous, hard and tenacious; resistant to corrosion by acids and alkalis. For making utensils, surgical instruments, cutlery, decorative articles, etc.
2. Nickel steel Fe – 95-98%

Ni – 2-5%

Hard, elastic and resistant to corrosion. For making electric cables, automobile parts, etc.
3. Vanadium steel Fe – 98-99%

C – 1-1.5%

V – 0.2-1%

Hard and brittle. For making rails, bridges, ships, tanks etc.
4. Chrome steel Fe – 94-98%

Cr – 1-4%

C – 1-1.5%

Hard and have very high tensile strength. For making swords, ball bearings, armour, dyes and high speed tools.
5. Manganese steel Fe – 82-84%

Mn – 15%

C – 1-1.5%

Hard and brittle For making money chests, hammering machines, army helmets.

 

 

ORES AND MINERALS

Minerals

The naturally occurring compounds of metals mixed with earthly impurities like sand, clay, stone, etc., are called minerals. They are found beneath the earth’s surface as the chemical ingredients of rocks.

Gangue

Earthly impurities like sand, clay and mud, when they are present in an ore, are called gangue or matrix.

Ores

An ore is a mixture of minerals from which elements or compounds are extracted. Generally ores are not exploited unless it can be done profitably.

 

Mineral + Gangue = Ore

COMMON ORES AND THE METALS EXTRACTED FROM THEM

Type of ore Ore Chemical formula Metal extracted
Oxide ores Bauxite

Haematite

Magnetite

Zincite

Cuprite

A2O3.2H2O

Fe2O3

Fe3O4

ZnO

Cu2O

A

Fe

Fe

Zn

Cu

Sulphide ores Galena

Copper glance

Iron pyrite

Zinc blende

Cinnabar

PbS

CuS

FeS2

ZnS

HgS

Pb

Cu

Fe

Zn

Hg

Carbonate ores Marble

Magnesite

Siderite

Malachite

Chalk

CaCO3

MgCO3

FeCO3

[CuCO3.Cu(OH)2]

CaCO3­

Ca

Mg

Fe

Cu

Ca

Sulphate ores Epsom slat

Gypsum

MgSO4.7H2O

CaSO4.2H2O

Mg

Ca

Halide ores Rock salt

Horn silver

Fluorspar

Cryolite

NaC

AgC

CaF2

AF3.3NaF

Na

Ag

Ca

A

 

 

 

 

KEY POINTS

  • Ingredient: A component part or element.
  • Exploit: Make use of and derive benefit from.
  • Pulverizers: Reduces to fine particles.
  • Consequences: A result or effect.
  • Smelting: Extract metal from its ore by a process involving heating and melting.
  • Conventional: Based on or in accordance with convention.
  • Electro-refining: Refining the metal by electric process.
  • Malleable: Able to be hammered or pressed into shape without breaking or cracking.
  • Ductile: Able to be drawn out into a thin wire.
  • Linseed oil: The oil obtained from the seeds of the flax plant.
  • Lustrous: A gentle sheen or soft glow.
  • Dentistry: Study of the diseases and conditions that affect the teeth and gums.
  • Barometer: An instrument measuring atmospheric pressure.
  • Divers: A person who dives under water as a sport or as part of their work.
  • Propellant: An inert fluid, liquefied under pressure.
  • Sterilizing: Make sterile
  • Fungicide: A chemical that destroys fungus.
  • Fumigation: Disinfect or purify with the fumes of certain chemicals.
  • Rectifier: An electrical device converting an alternating current into a direct one by allowing it to flow in one direction only.
  • Space age: Very modern, technologically advanced.
  • Disinfectant: A chemical liquid than destroys bacteria.
  • Suffocation: Have or cause to have difficulty in breathing.
  • Gilding: Trying to improve what is already beautiful or excellent.
  • Greasing: Applying a thick oily substance, especially is used as a lubricant.
  • Sonority: Capable of producing a deep or ringing sound.
  • Tensile: Capable of being drawn out or stretched.
  • Ascertain: Find out for certain.

 

  1. Conceptual Corner

 

  1. Why do metals acquire a dull appearance on exposure to air for a long time?
  2. Why are metals good conductors of electricity?
  3. In the laboratory, metallic sodium is stored in kerosene. Given reason.
  4. (i) What is an alloy?

(ii) A light and strong alloy is required for making for making the bodies of    aircrafts. What should be its constituents?

  1. Why is aluminium, and not iron, used for making cooking coil?

 

  1. Foundation Corner:

 

Level –I

 

Straight Objective Type

  1. Which is not the property of a metal?

          (A) malleability                                   (B) ductility

          (C) form acidic oxides                          (D) conductivity

 

  1. Which is a property of a non-metal?

          (A) If forms cations                              (B) It has have tensile strength

          (C) It has a high density                      (D) It form acidic oxides

 

  1. Calcination of an ore results in
  2. i) removal of moisture
  3. ii) porosity of ore

          iii) removal of volatile impurities

  1. iv) converts carbonate ore to oxide
  2. v) removes water of crystallisation from hydrated ores

          (A) (i) and (iv)                                      (B) (iii) and (iv)

          (C) (iii)                                                (D) all five options

 

  1. Roasting of an ore results in

          (A) conversion of ore to oxide               (B) metal it

          (C) makes it conducting                       (D) makes it soluble

 

  1. Froth flotation is a method used for

          (A) carbonate ores                               (B) hydrated ores

(C) sulphide ores                                 (D) oxide ores

 

Multiple Answers Correct Type

 

  1. What are the properties of a metal?

(A)      Malleable                        (B)     Ductile

(C)     Form acidic oxides           (D)     conductor

  1. What are the properties of a non – metal?

(A)      Forms anion                    (B)     Have tensile strength

(C)     High density                    (D)     Forms acidic oxides

 

Linked Comprehension Type

Alkali metal are Group I element and alkaline earth metals one group II elements. In between S-block and p-block elements there are fourth transition elements.

  1. Rb and Cs are :-

    (A)      Alkaline earth metal

(B)     Alkali metal

(C)     Rb is alkali metals and Cs is alkaline earth metal.

(D)     Both are transition elements.

  1. Fe, Mn and Co are the elements in which electrons are filled in.
    • S-orbital
    • P- orbital
    • d- orbital
    • All of the above.

 

 

ASSERTION AND REASON TYPE:

The following questions consist of two statements, one labeled the Assertion ‘A’ and the other labeled Reason ‘R’. You are required to examine these two statements carefully and decide if the assertion ‘A’ and reason ‘R’ are individually true and is so, whether the reason is a correct explanation of the assertion. Select your answers using the codes given below and mark your answer accordingly.

Code

Both A and R are true and R is the correct explanation of A:                   A

Both A and R are true but R is not a correct explanation of A:                 B

A is true but R is false:                                                                          C

A is false but R is true:                                                                         D

Both ‘A’ and ‘R’ are true:                                                                        E

  1. Assertion: Metals are sonorous.

Reason: Metals are generally brittle in the solid state, they break into pieces when hammered.

  1. Assertion: Sodium reacts with water, producing a hissing sound.

          Reason: Sodium reacts with water and produces hydrogen gas.

  1. Assertion: Zinc is used for galvanizing iron.

          Reason: Rust is hydrated ferric oxide.

  1. Assertion: Graphite is used as anode.

          Reason: Graphite helps in electron conduction.

  1. Assertion: Bronze has the composition Sn (90%), Cu (10%) and Zn (10%).

          Reason: Bronze is resistant over corrosion.

Matrix Match type

Column – I

Column – II

(A) Ductile (p) The property of making resonating sound.
(B) Malleable (q) A substance can be drawn into wires.
(C) Sonority (r) Ability to withstand the longitudinal pull.
(D) Stainless steel (s) Ability to withstand the longitudinal pull.

 

Integer Type

  1. How many metals are liquid at room temperate?

 

FILL IN THE BLANKS

 

  1. The two classifications of elements are _________ .
  2. Metals can produce sound when struck, this property of metals is known as _________.
  3. _________ is the metal existing in liquid form at ordinary temperatures.
  4. Metals react with mineral acids to form _________.
  5. _________ is a metal which does not conduct electricity.

 

Level 2:

Single Correct Choice Type:

  1. A metal and non-metal element are likely to combine to form ____________ bond.

(A) covalent                                        (B) ionic

(C) dative                                            (D) polar covalent

  1. Covalency of the bond(s) present in H2, F2, Cl2 is

(A) one                                                (B) two

(C) three                                             (D) four

  1. Ionic bond is formed between

(A) non-metal atoms                            (B) metal atoms

(C) metal and non-metal atoms            (D) none of these

  1. Ionic compounds have

(A) high melting point                         (B) high densities

(C) are crystalline solids                      (D) all (A, B, and C)

  1. A flux has all or some of these benefits except

(A) Lowers MP

(B) improves conductivity

(C) reacts chemically with impurities like sand

(D) refines the metal

 

Multiple corrects answer type

 

  1. Which of the following statement (s) are true?

(A)      Among all the naturally occurring elements, around eighty percent are metals.

(B)     Non – metals are more abundant than metals.

(C)     Sodium and potassium are soft like wax.

(D)     Bromine is a reddish brown liquid at room temperature.

  1. The basic oxides reacts with acids to form:

(A)      Salt             (B)     Water

(C)     Metalloid      (D)        All

 

Linked Comprehension Type

Metals have tendency to donate their valence electrons to get + vely charged metal ion. The amount of energy required to remove that electron is known as ionization energy It depends upon the electron configuration of an atom:-

 

  1. The first ionization energy of Na will be less than

          (A)      Mg               (B)     Zn

(C)     Ar                (D)     Both A and B

   

    the total ionization energy is equal to:-

    (A)             (B)

(C)            (D)

 

Matrix match type

 

Column – I

Column – II

(A) Brass (p) Aircrafts, pressure cooker
(B) Bronze (q) Utensils, automobile parts, cutlery
(C) Duralumin (r) Ornaments, bolts, utensils
(D) Stainless steel (s) Statues, coins

 

 

Integer Type

  1. How many non-metals are is the 2nd group of modern periodic table.

 

Fill in the blanks

 

  1. _________ metal exists in allotropic forms.
  2. Ornaments are usually made up of _________ gold.
  3. Most abundant element upon the earth is _________ .
  4. _________ is the non – metal which is lustrous.
  5. Iodine is used as an antiseptic in the form of _________ solution.

 

Level 3:

Single Correct Choice Type:

 

  1. When steam is passed through zinc, then:

(A)      Hydrogen gas is liberated          (B)     Zinc hydroxide is formed

(C)     zinc oxide is formed         (D)     HCI is formed

  1. 2X + 2Y ® 2XOH + H2

S + O2 ® Z

Z + Y ® P

 

  X Y Z P
(A) Na H2O SO2 H2SO3
(B) K H2O SO2 H2SO3
(C) Na H2O SO2 H2SO4
(D) K H2O SO2 H2SO4

 

Multiple Correct Answer type

  1. Transition compounds:

    (A)      Form coloured compounds

(B)     Shows variable oxidation state

(C)     Form complex compounds

(D)     None of these

  1. The elements which is / are liquid at room temperature

(A)                    (B)     Br

(C)     Cs               (D)     All of these

 

 

Linked Comprehension Type

Covalent bond is of two types one of them is polar covalent bond (HCl) and other is nonpolar covalent bond (N2) . Polar solute can be dissolved only in polar solvent and non-polar solute in non-polar solvent.

  1. NaCl can be dissolved in –

(A)                  (B)

(C)     Benzene                (D)     Chloroform

  1. HCl and contain:

(A)      Polar covalent & ionic bond respectively

(B)     ionic & polar covalent bond

(C)     Both contain only ionic bond

(D)     Both contain polar covalent bond.

 

Integer Type

  1. How many alkaline earth metal are in modern periodic table.

 

Fill in the blanks

  1. Edible common salt contains _________.
  2. In vapor state a metal is _________ atomic.
  3. Fizzy drinks are _________.
  4. H2 O, NO, CO, etc, are _________ oxides.
  5. Zirconium metal is used in making bulletproof alloy of _________.

 

 

ANSWER KEY

6 (C) 24. Hg 41. Graphite
7 (D) 25. Salt 42. Tincture
8 (D) 26. Hg 43. (A)
9 (A) 27 (B) 44. (A)
10 (C) 28. (B) 45. (A, B, C)
11 (A, B, D) 29. (C) 46. (A, B)
12 (A, C, D) 30. (D) 47. (A)
13 (C) 31. (C) 48. (A)
14 (C) 32. (C) 49. 6
15 (C) 33. (A) 50. Na+ and Cl
16 (D) 34. (A) 51. Mono
17 (C) 35. (D) 52.  
18 (A) 36. A – r, B – s,
C – p, D – s
53. Neutral
19 (A) 37. 6 54. Si
20 A – p, B – r,
C – p, D – s
38. Non    
21 1 39. Silver    
22 Metal and non meal 40.      
23 Sonority        

 

 

C.B.S.E Corner

Very Short –Answer Questions

 

  1. A substance is malleable, ductile and electropositive in natural.
  2. What property of a metal makes it possible to draw to into wires?
  3. Which of the following metals is the best conductor of heat and which, the poorest?
  4. Why are morals good conductors?
  5. Nonmetals usually do not have luster but there are exceptions. Name two such nonmetals

 

Short-Answer Question

 

  1. What is a metal?
  2. Explain why the surface of some metals acquire a dull appearance when exposed to air for a long time
  3. Mention any three properties of metal.
  4. How does a metal conduct heat?
  5. Explain the meaning of malleability’ and ‘ductility ‘of a metal.

 

Long answer type

 

  1. How do metals occur in nature?
  2. A metal ore, when heated in air releases sulphur dioxide gas. Explain how you would concentrate the ore.
  3. Mention the process by which a metal oxide be converted into metal.

 

 

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