Science Chapter 4 Materials : Metals And Non-Metals

A.

Zinc

C.

Generally, metals are ductile.

reactive

good

electricity

more

hydrogen

Aluminium foils are used to wrap food items because aluminium is highly malleable and can be beaten into sheets to form these thin wrapping sheets and it is soft and it does not react with food items.

Immersion rods are made up of metallic substances because metals are good conductors of heat and electricity. They get hot very soon and allow to passage of current and warm water.

Copper is less reactive than zinc and therefore, copper cannot displace zinc from its solution.

Sodium and Potassium are stored in kerosene because they are very reactive and quickly react in air.

No, we cannot store acidic lemon pickles in aluminium utensils because aluminium is a metal. Metals readily react with acids to produce metal salt and hydrogen gas. So, when the aluminium metal comes in contact with acidic lemon pickles, it would react to release hydrogen, which would spoil the food and render it unfit to consume.

Acid +Metal ---> Metal salt + Hydrogen gas

When sulphuric acid is poured on copper plate the sulphuric acid reacts with copper to form copper sulphate and hydrogen. The copper plate gets eroded from place.

Sulphuric Acid + Copper →

Copper Sulphate + Hydrogen

Iron is more reactive than copper, therefore when it place in copper sulphate solution, iron replace copper from its salt solution and iron sulphate solution is formed. 

Iron +copper sulphate→ Iron sulphate +copper
      _{(blue colour solution)     (green colour solution)} 

She will test it with litmus paper to check the acidic or basic nature of gas. If red litmus turns blue, it is basic in nature. If blue litmus turns red, it is acidic in nature. if colour is not change in both case then it is neutral.

Charcoal is form of carbon and burn in presence of oxygen, hence the chemical reaction that taking place is:

carbon +oxygen+heat → carbon dioxide

Goldsmith washed the jewellery with acidic solution such as aqua reiga. This aqua reiga solution dissovled metal in it. hence there was a slight loss in its weight.

Sodium and Potassium.

Mercury.

Sodium metal store in kerosene oil.

Aluminium foil is used in the packing of some of the medicine tablets.

The rust is Iron (III) oxide chemically.

The metal oxides are basic in nature.

(i) No change in the colour of blue litmus.

(ii) The red litmus changes into blue colour.

Sulphur dioxide.

Mostly non-metallic oxides are acidic in nature.

Sodium reacts vigorously with cold water forming sodium hydroxide and hydrogen.

Sodium + water →  sodium hydroxide + hydrogen

Phosphorus is kept in water.

The property of metals by which they can be beaten into thin sheets is called malleability. For example aluminium is beaten into sheets. 

The property of metals by which they can be drawn into wires is called ductility. Gold is most ductile element.

The property of metal to produce ringing sound is called sonority. 

Since metals produce ringing sounds, so they are called sonorous.

Copper and Aluminium are good conductors of both heat and electricity. 

Graphite is good conductor of heat and electricity.

Cooking utensils are made of copper or aluminium because they are good conductors of heat. 

Zinc and Magnesium. 

Magnesium will burn in the air.

Iodine non-metal is added to common salt.

The reaction in which a more reactive metal can replace a less reactive metal but a less reactive cannot replace more reactive metals are called displacement reaction.

For example Iron displace copper from its salt solution because iron is more reactive than copper but vice versa is not true.

When copper sulphate solution reacts with zinc, then it displaces copper.

Zinc +Copper sulphate --> zinc sulphate + copper

No reaction will take place as copper is less reactive than iron.

Silver and gold does not react with oxygen even at higher temperature.

Iron neither reacts with cold water nor with hot water but reacts with steam to produce hydrogen gas.

Iron +Water(steam) --> iron oxide +Hydrogen gas

Sulphur.

Copper and aluminium are both malleable and ductile.

Iron displaces copper from copper sulphate solution to form a light green solution of ferrous sulphate.

Electric wires are made of copper because it is good conductor of electricity and cheper than other metallic wire.

The property of metals by which they can be beaten into thin sheets is known as malleability. Silver and gold are the most malleable metals.

Non-metals are neither malleable nor ductile. 

(i) Metals can be hammered to make sheets so they are malleable.

(ii) Metals can be drawned into very thin wires, that means metals are ductile.

(iii) Metals are good conductors of heat and electricity.

(i) Non-metals are non-ductile and non-malleable.

(ii) Non-metals are non-sonorous.

(iii) Non-metals are poor conductors of heat and electricity.

(i) Zinc metal can displace copper from copper sulphate solution because zinc is more reactive than copper.

(ii) Copper cannot displace zinc from zinc sulphate solution because copper is less reactive than zinc.

Metals react with oxygen to form oxides generally. These oxides are basic.
Magnesium +Oxygen ---> Magnesium oxide
                                         (basic )

Non-metals react with oxygen to form oxides but these oxides are acidic in nature.

Sulphur  + Oxygen --> Sulphur oxide
                                    ^{(acidic )}

(i) MetaL is a good conductor of heat and electricity whereas non-metal is a bad conductor of heat and electricity.

(ii) metal is malleable which can be beaten into thin sheets whereas non-metal to brittle and breaks into pieces on beating.

Metals like sodium react vigorously with water to form sodium hydroxide and hydrogen. Magnesium reacts with hot boiling water to form magnesium oxide. Red hot iron reacts with steam to form Ferroso ferric oxide and hydrogen gas.

Sodium+water --> Sodium hydroxide +Hydrogen
              ^(cold) 
Magnesium+water(boiling) -->Magnesium Oxide +Hydrogen

Iron + water(steam) --> iron oxide + hydrogen

Non - metal does not react with water.

Sulphur is a non-metal because:

(i) It is neither malleable nor ductile.

(ii) It does not conduct heat and electricity.

(iii) It combines with oxygen to form acidic oxide.

Zinc is more reactive than iron therefore, the pale green colour of iron sulphate will fade and a colourless solution of zinc sulphate will be obtained. Greyish particles of iron are also formed.

Zinc +Iron Sulphate  --> zinc sulphate + Iron
          ^{plae green colour)      ( colourless)}  

(i) Sodium is very reactive that it reacts vigorously in air and catch fire. Hence to protect it, it is stored under kerosene.

(ii) Aluminium is a good conductor of heat. Moreover when exposed to air its surface gets covered with thin layer of oxides which prevents metal underneath from further corrosion. Hence it is used to make utensils for cooking.

The element A which is stored under water forms an acidic oxide is white phosphorus whereas element B which is stored under kerosene and forms a basic oxide is sodium, when white phosphorus burns in air, it forms phosphorus trioxide and phosphorus pentaoxide.

Phosphorus + Oxygen → Phosphorus tri oxide Phosphorus + Oxygen→ Phosphorus pentaoxide

When sodium react with oxygen, it forms sodium oxide.
Sodium +Oxygen ---> Sodium oxide.

Iron metal being more reactive than copper, displaces copper from copper sulphate solution to form Iron sulphate solution and copper metal.

Copper Sulphate Solution + Iron →

Iron Sulphate Solution + Copper

Holes are formed at those places in the iron pot from where iron metal has dissolved to form iron sulphate solution.

Copper is more reactive than silver therefore, when a copper coin is kept immersed in silver nitrate solution, then :

(i) A shining white deposit of silver metal is formed on the copper coin.

(ii) The colour of solution changes to blue due to the formation of copper nitrate solution.

Yes, we have seen blacksmith heating the iron pieces. We have seen the changes in the shape on heating. It increases in size and it does not break. But when wood log is beaten, it does not change its shape but it breaks into pieces.

When a copper vessel is exposed in moist air for a long time, it acquires a dull green coating. The green substance is the mixture of copper hydroxide and copper carbonate.

Non-metals do not react with water. This quality is quite helpful in protecting some highly reactive non-metals which quickly react in air. White phosphorus is very reactive non-metal. It immediately catches fire when exposed to air. To prevent this, it is stored in water.

Certain food stuffs such as citrus fruits, pickles and curd should not be stored in containers made of metals such as copper, zinc, aluminium and iron. This is because these food stuffs contain acids which react with these metals to produce toxic and poisonous compounds. These toxic poisonous compounds cause food poisoning.

When Magnesium and aluminium react with dilute acid, it forms Magnesium chloride and aluminium chloride respectively and hydrogen gas is involved.

Magnesium + Hydrochloric acid(dil.)--> Magnesium Chloride + Hydrogen gas

Aluminium + Hydrochloric acid (dil) --> Aluminium Chloride + Hydrogen gas


 

(i) It is used for making electrical wires and cables.

(ii) It is used for making domestic utensils and factory equipments.

(iii) It is used for making metallic paints.

(iv) The foils of aluminium are used for packaging food materials and medicines, etc.

i) Reaction with oxygen : Sodium catches fire when kept open in the air, so sodium reacts very vigorously with oxygen.
Magnesium reacts with oxygen only on heating whereas copper reacts with oxygen on very strong heating. These reactions show that here sodium is the most reactive metal and copper is the least reactive metal. So, the decreasing order of reactivity is:

Sodium > Magnesium > Copper.

(ii) Reaction with water : Sodium reacts very vigorously even with cold water. Magnesium reacts slowly with cold water but rapidly with hot, boiling water, whereas copper does not react even with steam. This activity also shows that here sodium is the most reactive metal and copper is the least reactive metal. So, the order of their decreasing reactivity is : Sodium > Magnesium > Copper.

This can be easily proved in laboratory. Take some rust and dissolve it in water (a few drops). Now take a red litmus paper and dip the litmus paper in solution. We will see that the red litmus paper turns blue. When the red litmus paper turns blue it means solution is basic in nature. So the rust is basic in nature. We can similarly check the nature of ash obtained by burning a magnesium ribbon. It will also turn red litmus paper blue proving its basic nature.

Metals are very useful to us. Some of the uses of common metals are following :

(a) Copper and aluminium metals are used to make electric wires. This is because copper and aluminium are good conductors of electricity.

(b) Copper, aluminium and iron metals are used for making utensils and other domestic things. These metals are also used to make various factory equipments. This is because, all these metals are good conductors of heat.

(c) Iron is used to make heavy machinery and is also used in construction of buildings because it is very heavy and strong.

(d) Thin foils of aluminium are used in packaging food materials and medicines etc.

(e)The liquid metal mercury is used in thermometers.

(f) Gold and silver metals are used to make jewellery.

(g) Sodium, titanium and zirconium metals are used in atomic energy and space projects.

(a) Oxygen is used by plants and animals for respiration. Oxygen also supports the process of combustion in factories, houses, aeroplanes and missiles.

(b)Compounds of nitrogen provide nutrients to soil and plants. Fertilizers made by using nitrogen are extensively used in agricultural practices.

(c) Chlorine is used to disinfect the drinking water as it has the ability to kill germs.

(d) Sulphur is also used as germicide, it is also used as an antiseptic for skin treatment (in ointments).

(e) Non-metals are used in crackers.

(a) This figure shows the malleability property of metals.

(b) (i) Hammer. (ii) Iron nail.

(c) Gold and silver.

(d) Sodium and potassium are not malleable.

a) (1)—cell, (2)—Bulb, (3)—Iron nail.

(b) The figure shows the property of conductivity of metals.

(c) Copper and silver.

(d) Graphite.

(a)
Beaker A : Copper Sulphate (CuSO4) + Zinc granite (Zn)

Beaker B : Copper Sulphate (CuSO₄) + Iron nail (Fe)

Beaker C : Zinc Sulphate (ZnSO₄) + Copper turnings (Cu)

Beaker D : Iron Sulphate (FeSO₄) + Copper turnings (Cu)

Beaker E : Zinc Sulphate ZnSO₄) + Iron nail (Fe)

(b)
Beaker A : Copper Sulphate + Zinc → Zinc Sulphate + Copper

Beaker B : Copper Sulphate + Iron → Ferrous Sulphate + Copper

Beaker C : Zinc Sulphate + Copper → No reaction

Beaker D : Iron Sulphate (FeSO₄) + Copper turnings → No reaction

Beaker E : Zinc Sulphate (ZnSO₄) + Iron (Fe) → No reaction

In beakers A and B displacement reaction takes place.

(ii)

Aluminium > Zinc > Iron > Copper

basic

mercury

bromine

ductile

kerosene oil

sodium

Graphite

hydrogen

oxides

silver

copper

D.

Potassium

C.

silver

B.

Hydrogen gas

C.

Zinc is more reactive than iron

A.

Mercury

C.

Sodium

B.

Sodium

D.

Gold

A.

Iron

B.

Bromine