METAL AND NON METALS

# ELEMENT

Definition

An element is a pure substance which is made up of same kind of atom which differ from their physical and chemical properties.

115 elements are known under which 92 are naturally occurring. Classification of elements

Elements can be classified into 3 types

Metals Non metals Metalloids

CLASSIFICATION OF ELEMENTS

METALS NON METALSMETALLOIDS

COMBINED STATEFREE STATE

GOLD

SILVER

PLATINUM

NA, K, Cain the form of catbonate

, oxides, sulphide

silicon,germanium,

arsenic

COMBINED STATE

FREE STATE

Oxygen, Nitrogen, sulphur, Carbon in the form of graphite, diamond.

Sulphur and carbon in the form of oxides,

carbonates , sulphides

Some abundant elements Aluminium(most) Iron

Most abundant non metal Oxygen

Less reactive metal Gold Silver Platinum

Most reactive metals Sodium Potassium Calcium

Non metal existing in free(native) and combined state Sulphur Carbon

DIFFERENCE BETWEEN MINERAL AND ORE

Mineral oreA mineral is a naturally occurring inorganic substance found deep inside the earth surface

Ore is a mineral from which one or more metals can be extracted economically and profitably.

Examples of ore

Ore of Iron – Hematite ( Fe2O3) ; Magnetite( Fe3O4)

Ore of aluminium – bauxite( Al2O3.H2O) ; Cryolite (Na3AlF6)

METALLURGY

DEFINATION

Sequence of processes to extract a metal in its pure form from its ore is called metallurgy.

STEPS OF METALLURGY

METALLURGY

STEP 3REFINING OF METAL

STEP 2REDUCTION

STEP 1CONCENTRATION

OF ORE

CONCENTRATION OF OREIt is the process of removal of impurities from its ore.

REDUCTIONIt is the process of the reduction of the metal ire to get the metal in its free state.

REFINING OF METAL

The metal obtained in the second step is impure. Refining is the process of purification of metal.

Physical properties

Property Metal Non metal

Physical state Are generally solids except mercury(liquid state)

Occur in Solids- carbon,

sulphur, phosphorous. Liquid- bromine Gas- oxygen, nitrogen

Lusture Have shiny appearance Dull appearanceException

Graphite Iodine

Melting & Boiling point High mp.pt and bp.ptExceptionCesium has mp.pt of 28.70c

Low mp.pt & bp.pt

ExceptionCarbon has hiogh mp.pt of 37230c

Hardness Very hard & can withstand high pressure.Exception Na & K are soft and can be easily cut by knife.

Soft

ExceptionDiamond, hardest known substance.

Density High Low

Ductility Metals are ductile

Ductility is defined as the property of metals to be drawn into thin wires.

Most ductile metalsGold & silver.

Non ductile.

Malleability Metals are malleable

Malleability is defined as the property of metals to be drawn into thin sheets on hammering.Most malleable Gold and silver

Non ductile

Conductivity Thermal

conductivity

Electrical conductivity

Property of metals that allows conduction of heat from one region to another.

Property of metals that allows conduction of electricity from one region to

Bad conductor of heatException

Graphite

Bad conductors of current

another.

Exception

Lead and mercury are bad conductors

Exception Graphite(form of carbon)

Sonorosity Property of metals to produce a ringing sound when struck.

NON SONOROUS

METALLOIDS

There are some metals which show some properties of a metals and non metals. Such elements are called metalloids.

Examples: ARSENIC, GERMANIUM, SILICON

NOBLE METALS

Definition

Those metals that have least reactivity and do not react with air, water, acids and bases are referred to as noble metals.Two noble metals are: GOLD, PLATINUM

Q why noble metals do not get tarnished?

Q silver jewellery when kept in open gets tarnished after some time. Why?

Pure gold is soft and its purity is measured in units called CARATS. If gold is 22 carats pure, it means that 22 parts of gold are present in 24 parts of mixture of gold with copper and silver.

Copper and silver are added to make pure gold hard.

Q why gold is alloyed with silver and copper?

USES OF METALS.

ALUMINIUM

USE PROPERTYIn electrical cables Good conductor

Ductile (can be drawn into thin wires.)

In making cooking utensils Good conductor of electricity.Making aluminum foils Malleable(can be beaten into

thin sheets on hammering) Good conductor of heat

To make alloys like duralumin(for making aircraft)

Light and strong

COPPER

USE PROPERTYIn electrical cables Good conductor

Ductile (can be drawn into thin wires.)

In making cooking utensils Good conductor of electricity. # GENERAL USES OF METALS

For making electrical fittings, net doors, wires as metals are ductile.

Gold, silver, platinum are used fir making jewellery because of its lusture, ductility and malleability.

Are used for making bells, because of the property of sonorosity, which gives ringing sound when struck.

Iron is used for making cooking utensils , water boilers , chains because of its strength, malleability, ductility and versatility.

CORROSION

# DEFINITION

Eating away of metals is called corrosion.

# Conditions for corrosion to occur

Presence of air Presence of water.

# RUSTING

It is the type of corrosion which occurs die to the formation of brown colored layer of iron oxide called rust formed on iron when exposed to moist air.

Chemical Formulae Fe2O3 .XH2O

Chemical reaction

Iron + water + oxygen    →    hydrated iron (III) oxide

Fe(s) + 3O2(g)+ XH2O 2Fe2O3 .XH2O(s)

Aluminium does not rust - corrode. Its surface is protected by a natural layer of aluminium oxide. This prevents the metal below from coming into contact with air and oxygen.

#To study the conditions necessary for corrosion to occur.

Take three test tubes A,B,C and put iron nails in each of the test tubes.

In test tube A fill it half with tap water. In test tube B add boiling water and pour oil over it. In test tube C add anhydrous calcium chloride(cacl2)

Observation

Test tube Observation inferenceA Rusting occurs Since it has both air &

water. Iron reacts to form Fe2O3 .XH2O

B No rusting occurs Since the boiled water expels the air from it and oil layer prevents further reaction with air.

C No rusting occurs anhydrous calcium chloride(cacl2), absorbs the moisture from the air present in the test tube. So in the absence of air no rusting occurs

ACTIVITY TO SHOW HOW RUSTING OCCURS

# WAYS TO PREVENT CORROSION

Oiling and greasing It cuts off the contact between the metal and moist air and prevents it from rusting.

Painting

Paint also cuts off the contact between the metal and moist air and prevents it from rusting.

Galvanisation

It is the process of coating the surface of iron with the layer of zinc metal.This is done by dipping the iron objects into molten zinc.

Electroplating

It is the process of depositing thin layer of another lesser reactive metal like tin or chromium on its surface with help of electric current.