METALS

• Iron• Aluminium• Copper• Zinc• Magnesium

Properties of metals

• Strong , hard and dense• Solids at room temperature• High Melting point• Good electrical and heat conductors• Shiny • Malleable and ductile

Copper

• Ductile• Electrical conductors• Cooking utensils

Silver and Gold

• Non reactive• Malleable and ductile• Jewellery• Computer fibres

Iron and steel

• Strong and hard• Ships , bridges and buildings• ‘Rust’• Use antirust

Energy is needed to extract metals

Gold , silver highly non reactive , so present in their pure formMg,Na,Al ,Fe reactive Found in their ores

• MINING ( Ore From Ground) MILLING ( Crushing , Concentrating And Purifying) SMELTING ( Chemical Means) REFINING ( Purifying The Crude Metal)

IRON

• Hematite ( )• Magnetite ( )• Siderite ()• Limonite• Iron pyrites

SMELTING

+ C Fe + C

[SMELTING] FOR LOWER MP metals ( Fe , tin , Cu)800 degree C , low oxygen content environment

PURIFYING METALS USING ELECTRICITYAnode Impure MetalConducting solution( electrolyte)Cathode Pure Metal

Impurities dropped inside the vessel ( non conductors)

ALUMINIUM

Most abundantExtracting it is a difficult taskMany historical methods of extracting aluminiums i) Heating in the presence of potassium mercury amalgam

Uses of Aluminiumi) Aircrafts & defence ( Light weight and strong)ii) Doesn’t corrode as the self healing oxide helps against rustingiii) Paper foils

Charles Hall Method of Al extraction

Dissolving Alumina in the mineral cryolite

℃

Alloys

Pure metals Soft and brittle , quite reactiveAlloy Mixture of two or more elementsProportion of metals in a given alloy can change

STEEL IRON and CARBONBRASS COPPER and ZINCBRONZE COPPER and TINDURALUMIN Aluminium and Tin

STEEL

IronCopper (0.2-2.4% by weight)

Hardening agentsManganeseChromiumTungsten

STEEL

Stainless Steel 10% chromium , magnetic/non magnetic

Increasing the carbon content can make the strength higher

Carburising A process of increasing the amount of carbon in steel by 0.5-1% to make it hard.

BRASS

Copper and Zinc

Decorationlocks , gears , bearings and valvesPlumbing and electrical equipmentMusical instruments

More malleable than either copper or zinLow MP , recycleAddition of ‘Aluminium’ makes it stronger and corrosion resistant

SOLDER

Fusible Metal alloyTin and LeadMelting Point 90-150 ℃Join metallic surfaces , plumbing , electronics soldering

Bronze

• Copper (90%) and Tin (10%)• Weapons• Musical instruments and weapons

Gold and other alloys

Gold -> Softer as compared to other alloysSterling silver Silver and CopperPlatinum Pure form , ductile , but if you add cobalt or iridium it becomes stronger

Reactivity of Metals

Reaction with dilute acid

Ca > Mg > Zn > Cu

Bubbles of hydrogen gas Effervesces

Reactivity of Metals

Reaction with waterSodium when kept in air MOISTURE TarnishIt is stored in air-tight containers

Na , K , Li ,Ba and Ca React with water

Al , Zn and Fe react with steam

Cu , Ag , Au , Pt , Sn , Pb Don’t react with water

Reactivity of Metals

Reaction with oxygen

Ag , Au and Pt Don’t react with oxygen

Burn rapidly in air K , Na , Ba , Ca , Mg

Reacts slowly Zn , Fe ( rusting)

Very slowly Al , Cu , Hg

Balance the reactions

Mg + HCl + Na + NaOH + Ca + CaO

Order of reactivity

Mg > Al > Zn > Fe > Pb > Cu

More reactive the metal , more stable the carbonate

Difficult to decompose the carbonate if it is highly stable

MgC is stable the CuC

Activity Series of Metals

K Na Ca Mg Al Zn Fe Sn Pb Cu Ag Pt Au

RED Metals requiring electrolysisBlack Reduced by C or CO

Activity Series of Metals

Acid on Metal Hydrogen gas and Salts

Oxygen/Air on Metal Produces oxides and burns

Sacrificial Electrodes

Coating of Zinc over the cast iron motor body prevents it from rusting.

Since Zn is more reactive than Fe , it corrodes faster

First Ionization Energy

The first ionisation energy is defined as the energy required to remove one mole of electrons from one mole of gaseous atoms to provide one mole of gaseous single charged ions.

Na(g) --> Na+(g) + 1e

• Subsequent ionisation energies are defined in a similar way only by removing electrons from already charged ions.

First Ionization Energy

• Group 14

Mole

Avogadro's Number 6.022 x (NA)

Number of atoms in 12grams of Carbon -12 isotope

Number of moles = Number of particles / Number of particles in one mole

n = N / NA

Moles

Number of moles = mass of the given substance / Mass of one mole

Moles Grams (Molar Mass )Number of particles ( NA)

Conservation of volume

The pressure of a gas of fixed mass and fixed volume is directly proportional to the gas's absolute temperature.