METALS AND NON METALS (CBSE CLASS 10)

METALS AND NONMETALS 

Metalloids 

These element that have property like metal and nonmetal are known as metalloids 

example 

Germanium and silicon 

Metal And Nonmetals 

Metal:- is defined as the element which form positive ions by the loss of electrons

• metals are electropositive

example 

sodium is a metal

Na+----->Na-e-

Non Metal 

Non metals are defined as the element which form Negative Ion by the gain of electron

Example

Chlorine

Cl+e------->Cl-

• the number of electrons lose or gain by an element is equals to its valency 

General Properties Of Metals 

• Metals are generally solid at ordinary temperature exception Mercury 
• They are volatile at high temperature
• They are hard in nature exception Sodium and potassium and lead a soft metal
• They have got Shiny metallic lustre
• They have high density exception Sodium and potassium 
• They have high melting and boiling point due to closely packed structure
• They are malleable and ductile
• They are good conductor of heat and electricity
• they have very high resistivity
• metals are sonorous that means they produce sound

General Properties Of Non Metals 

• Non metals are usually gaseous or liquid exception carbon sulphur phosphorus
• They are volatile at low temperatures exception carbon Boron and silicon
• They lack lustre exception iodine and graphite
• They are soft in nature exception diamond 
• They have low density
• They have low melting and boiling point
• They are non malleable and ductile exception carbon fibres 
• They are poor conductor of heat and electricity exception graphite and gaseous carbon 
• they are brittle in solid state
• they are not sonorous

Question 

Why group first A(1A) element are known as alkali metal ? 

Because they react with water to form their Hydroxide which are strong alkali.

Characteristics Of Alkali Metals 

• Alkali metal cannot exist in a free state in nature because they are highly reactive
• All alkali metals are salt and ionic in nature
• They are soft and having low melting and boiling point

Action With Air 

• they react rapidly with oxygen water vapour in the air

M+Oxygen--------->Metal Oxide 

• Down the group reactivity of these group increases

Action Of Acid 

• They react violently whith dilute HCl and dilute H2SO4 to produce hydrogen gas

2M + 2 HCl ------> 2MCl  +  H2

2M +  H2SO4 ------> 2MSO4  +  H2

• They have low first ionization energy second ionization energy is very high
• They are strong reducing agents

Alkali Earth Metals 

• All alkali metals are generally grey hard with high melting and boiling point and low density
• Alkali Earth metals combine exothermically to form stable compound
• The oxides of alkali Earth metals have a very high heat of formation and therefore are very difficult to reduce by conventional reducing agent
• Dissolve in water to give basic hydroxide
• All the compounds are colourless except if the ions are colourless the compound will not be colorless most
• Most of salt of metal alkali earth metal soluble in water but these phosphate carbonate Chloride and oxalate generally are not

Reactivity Series 

The arrangement of metal in the decreasing order of the reactivity is called reactivity series of metal

K>Na>Ca>Mg>Al>Zn>Fe>Pb>H>Cu>Hg>Ag>Au

• The electropositive character decreases on moving down the series
• Higher the metal in reactivity series stronger is it  tendency to exist as ions in solution
• The most reactive metal are placed on top on going down the activity decreases

METALLURGY 

It is the process of extracting the metal economically and profitably from the ore and refined the extracted material into purer form.

Ore 

• An ore is the mineral from which metal can be extracted profitably and conventionally or easily
• Ore are compounds of metal which are found in nature with earthly impurities

Note

all Ores are minerals but all minerals are not ores 

Gangue 

it is the impurity associated with the mineral like clay and silicate

Flux 

flux is a substance that is added as charge in the Furnace to remove the gangue

Slag

Flux combined with the gangue to form fused Mass called slag

SiO2 + CaCO3 ---------> CuSiO3 (slag) + CO2

Smelting 

It is the process of reducing roasted oxide Ores and removing the gangue with the help of an appropriate flux added with roasting

Smelting is a pyrochemical process, in which the ore is mixed with flux and fuel then is strongly heated. Smelting is carried out in a specially built furnace known as blast furnace.

Roasting 

The sulphide Ores are converting into oxides by heating strongly in the presence of excess air is known asRoasting

Roasting is a pyrochemical process in which the ore is heated in the presence of oxygen or air is below its melting point roasting is done in reverberatory furnace.

Example

2ZnS(s) + 3O2 -------> 2 Zno + 2 SO2

,

Calcination

The carbonate Ore are changes into oxide by heating strongly in Limited supply of air this is known as calcination.

Calcination is also a pyrochemical process  in which ore is heated in the absence of air

 Example

ZnCO3---------->ZnO + CO2

Enrichment Of Ores 

• The process used for removing the gangue from the ore known as enrichment of ore,concentration of ore , dressing of ore
• It use different physical chemical properties of the gangue and ore to separate them

Example 

Froth Flotation ,Gravity Separation ,Magnetic Separation

Extracting Metals Low In The Activity Series 

metals low in the activity series are very unreactive the oxide of these metals can be reduced to metal by heating alone

Example:-

2HgS(s)+3O2(g)-------->2HgO(s)+2SO2(g)

2HgO(s)-------->2Hg(l)+O2(g)

Thermite Reaction 

the reaction of iron oxide with aluminium is used to join railway track , machine parts this reaction is known as the thermite reaction

Fe2O3(s) + 2Al(s) ----->2Fe(l) + Al2O3(s)+Heat

Extracting Metals Towards The Top Of The Activity Series 

• The Metals high up in the activity series are highly reactive
• These metal cannot be obtained from the compound by heating with carbon because these metals have more affinity for oxygen than carbon
• These metals are obtained by electrolytic reduction
• The metals are deposited at the cathode the negatively charged electrode whereas chlorine is liberated at the anode the positively charged electrode

reaction 

At Cathode :- Na++ e-------> Na

At Anode:- 2Cl-------->Cl2+2e-

Electrorefining 

Electrorefining is a process by which metal contain impurity are purified electrically to give pure metals

Anode Mud 

Anode disintegrate discharging copper in the solution impurities from the anode settle down at the bottom of the anode electrode and are called anode mud

Electrolyte :- acidified aqueous solution

Electrode:-

• cathode:- thin sheet of copper
• anode:- impure block of copper

reaction 

At Cathode :- Cu2++ 2e-------> Cu

At Anode:- Cu-2e-------->Cu2+

Corrosion 

when the surface of a metal is attacked by Air moisture or any other substance around it, the metal is said to be corroded and the phenomena is known as corrosion

Rusting 

• Corrosion of iron is known as rusting
• Rusting is the slow oxidation of iron by atmospheric oxygen in the presence of water
• It is a wasteful reaction it may lead to collapse of bridge, building, leakage of road and other harmful consequences

Fe2O3.XH2O (Brown Powder)

Prevention Of Corrosion 

There are different ways by which we can prevent corrosion

• Painting :_railing ,lamppost ,window paint can be prevented by painting
• Tar coating:- the lower part of ship or bridges are prevented by rusting by tar coating
• Greasing:- fast moving iron parts of machinery are prevented by rusting
• Enamelling:- ports
• Plastic coating:- steel pipe, Garden chair etc are prevent by rusting in the process of plastic coating
• Galvanization:- in this process iron is coated with zinc should attend to prevent them from rusting