Download - IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

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Page 1: IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

Allotropes of Carbon Element exist in different form/physical state

Diamond Fullerene, C60

• Carbon- sp2 hybridization • Bonded in geodesic shape• 60 carbon in spherical - 20 hexagon/ 12 pentagon• 1 π electron free to delocalized. • Surface is not planar, but sphere• Electrons NOT able to flow easily.

Graphene

• Carbon- sp2 hybridization• Carbon bond to 3 others form hexagon (120) • Exist chicken wire/honeycomb- 1 layer

Click here to viewClick here to view Click here to view

• Carbon- sp3 hybridization• Bonded tetrahedrally• Strong hard covalent network

• Carbon- sp2 hybridization• Bonded Trigonal planar (layers)• Giant covalent structure (2D)• Strong covalent network within layers• Weak Van Der Waals force bet layers

Giant covalent structure (3D)

Giant covalent structure (2D)

Molecular structure

✓✓

Giant covalent structure (2D) ✓

Uses of graphene

Graphite

Bond to 4 C atoms

Bond to 3 C atoms

Bond to 3 C atoms

Page 2: IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

Allotropes of Carbon Element exist in different form/physical state

Diamond Fullerene, C60GrapheneGraphite

Electrical conductivity

Special property

Electrical conductivity Electrical conductivity Electrical conductivity

Special property

Good

- Within layer, C sp2 hybridized- ONE free delocalized π electron

Very Good

- Within layer, C sp2 hybridized- ONE free delocalized π electron

moving across the layer easily

Poor

- C sp3 hybridized- No free moving electron

Semiconductor ✓✗

- Surface sphere, not planar- Electrons CANNOT flow easily.- Lower electron mobility

- Soft, layer slide across each other

- Hardest substance- Jewellery

Special property

graphite lubricant electrode

Lightest/strongest material

replacing silicon in photovoltaic cell

Drug delivery Transistor/ElectronicTransparent conducting

electrode

Click here uses grapheneDrug in graphene

Page 3: IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

Allotropes of Carbon Element exist in different form/physical state

Fullerene, C60Graphene

Click here to view touch screen

Electron in hexagonal rings do not

delocalized over whole molecule.

6:6 bond shorter than 6:5

6:5 bond bet hexagon and pentagon

Macroscopic properties• High tensile strength• High electrical /heat conductivity• High ductility and chemical inactivity

60 carbon in spherical((20 hexagon/12 pentagon)

Potential medicinal use• Trap/bind drug inside/outside cage• Target cancer cells

Drug inside Drug bind outside

• sp2 hybridization• Exist as 2D/chicken wire/honeycomb• Stronger than diamond, x200 stronger steel• Conductive than copper• Flexible/Transparent/lighter than rubber• Solar cell and batteries

Graphene touch screen and photovoltaic cell

Click here for application of graphene

Single sheet conductor Rool into conductive nanotubes

Electrical contact

photovoltaic cell

Lightest and strongest replacing silicon in photovoltaic cell

6:6 bond length bet two hexagon

Double bondSingle bond

Page 4: IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

Uses of Carbon Allotropes

• Conduct current/heat very well• Conduct current at speed of light • Electron delocalized above/below plane• High electron mobility

Click here discovery graphene Click here CNT Click here to view

sp2 hybridization

graphene

rool into rool into

Carbon Nanotube (CNT)

CNT- fullerene family of carbon allotropes. Hollow cylindrical moleculeRolling single or multiple layers of graphene sheet. Single-wall SWNT/ multi-wall MWCNTHigh tensile, stable, unreactive

Single wall Nanotube (SWNT) Multi wall Nanotubes (MWNT)

Click here TEDtalk graphene

1 layer thick

Uses of CNT

Strong tubes as

space elevatorFilter off salt

(desalination)

Drug delivery to body Attachment drug

therapeutics

Page 5: IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

Metallic Bonding

MetalsMetallic bonding

Electrostatic forces attraction - bet lattice of positive ions with

delocalized electron

Metallic elements- Cu, Na, K, Cu

Lattice of positive ions with sea of free electrons

Metallic Bonding

Metallic Property

Electrical conductivity Malleability/Ductile High melting point

Delocalized free moving electron carry charge/heat

heat flow

High Temp Low Temp

Thermal conductivity

electron flow

Form sheet by hammering

Ductile -stretch into wires

Bend and shaped

Atom able to roll/slide to new position

without breaking metallic bond

Strong Electrostatic force attraction - between lattice of positive ions with

delocalized electron

Page 6: IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

Melting Point • Temp when solid turn to liquid (temp remain constant)• Energy absorb to overcome forces attraction bet molecule

Factors affecting melting point for metals

• Melting point across Period 2/3• Melting point down Gp 1

Gp 1

Period 2/3

Metallic Bonding

Melting Point metals

period 2

period 3

Li

Be

B

C

N O F Ne

Na

MgAI

Si

P SCI

Melting point across Period 2 and 3

Electrostatic forces attraction - bet lattice of positive ions with

delocalized electron

Melting point across Period 2 and 3

Size of atom decrease ↓ Number delocalized electron increase ↑

Electrostatic forces attractionINCREASES ↑

Melting point INCREASE ↑ ✓

Electrostatic force attraction

Metallic Bonding

Metalic Bonding INCREASE ↑

Page 7: IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

Melting Point

Factors affecting melting point for metals

Gp 1

Period 2/3

Metallic Bonding

Melting Point metals

Melting point down Group 1

Electrostatic forces attraction - bet lattice of positive ions with

delocalized electron

Melting point down Gp 1

Size of atom increase ↑ Valence electron furtheraway from positive nucleus

Electrostatic forces attractionDECREASES ↓

Melting pointDECREASE ↓ ✓

Electrostatic force attraction

Metallic Bonding

Size of atom increases

Metallic BondingDECREASE ↓

• Temp when solid turn to liquid (temp remain constant)• Energy absorb to overcome forces attraction bet molecule

• Melting point across Period 2/3• Melting point down Gp 1

Page 8: IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

Melting Point

Gp 1

Period 2/3

Metallic Bonding

Melting Point metals

Electrostatic forces attraction - bet lattice of positive ions with

delocalized electron

Electrostatic force attractionMetallic Bonding

Number delocalized electrons

Factors affecting Metallic Bonding

Charge on cation Radius cation

Higher ↑ charge cation

Higher ↑ metallic bonding(melting point)

Bigger ↑ radius cation

Lower ↓ metallic bonding(melting point)

Higher ↑ number delocalized electrons

Why m/p Na (Gp 1) less than Mg (Gp 2) ?Why melting point

different?

ONE delocalized

electron per atomTWO delocalized

electron per atom

Radius cation Bigger ↑ Radius cation Smaller ↓

MELTING POINT MELTING POINT

Higher ↑ metallic bonding(melting point)

Charge cation smaller ↓ Charge cation Bigger ↑

• Temp when solid turn to liquid (temp remain constant)• Energy absorb to overcome forces attraction bet molecule

• Melting point across Period 2/3• Melting point down Gp 1

+1 +2

Page 9: IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

Heating mixture metals together

Alloy cool/solidifies, mechanical property diff from its individual constituentsMetals/non-metals often enhance its properties.

Induce strength/hardness by occupying empty spaces bet lattice structure

Metals • Same type of elements/atom arrangement• Malleable – shaped by hammering• Ductile –deform/ turn to wire

Aluminium- Soft/malleable

structure - crystalline lattice same type atoms

Click here for list of alloys

Metals Vs Alloy

Alloy• Mixture metals / non metal• Property alloy far superior than its element/metal• Stronger, harder and enhanced qualities than metals

structure - crystalline lattice different atomic sizes

Duralumin (Aluminium + Copper)Strong aircraft

Metals Alloy

Vs

Vs

Iron- Soft/malleable

Steel- Strong/Hard

What makes alloy strong?

Metal occupy spaces

in between

Heat mixture metals

Malleable (hammer) Ductile (Stretch)

Mixture of metals

in lattice

Strong + hard

✓✗

Click here uses alloy - nitinol robot

Page 10: IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

Metals

Structure - crystalline lattice same type atoms

Metals Vs Alloy

Property alloy far superiorthan its element/metal

Structure - crystalline lattice different atomic sizes

Vs

Malleable (hammer) Ductile (Stretch) Mixture of metals

in lattice

Alloy Component Property/Uses

Steel Iron + Carbon Structural material

Stainless steel Iron + Carbon +Nickel +Chromium Corrosion resistance

Brass Copper + Zinc Decorative

Bronze Copper + Tin Coins and medals

Duralumin Aluminium + Copper + Manganese Aircraft

Nichrome Nickel + Chromium Heating element

Pewter Tin + Copper + Antimony Decorative

Nitinol Nickel + Titanium Shape memory, actuator

Bold – Base main metal used

Same type atomarrangement

Ductile –Deform/turn to wire

Malleable –Shaped by hammer

Alloy

Mixture metals/non metal

Stronger, harder- enhance qualities than metals

+

Metal + Metal = Alloy

Click here different alloys

Types of Alloy

Steel Stainless steel Brass Bronze

DuraluminNichrome

Pewter

Click here uses alloy - nitinol robot

Page 11: IB Chemistry on Allotrope, Alloy, Graphene and crystalline structure

Crystalline Structure

Giant metallic Giant Ionic Giant Covalent Network

Simple Molecular

Non Polar Polar molecule H2 Bonding

Particles Atoms(Metals)Na, K, Li, Ca, Mg

Ion (+ve/-ve ions)Na+CI-, K+CI-

Atoms from Gp4 (Carbon/Silicon)

Molecules with Molecule with Molecule with H atom - Similar EN value - Different EN value - bonded to N, O, F- Bond polarity cancel – Dipole moment (electronegative atom) - Symmetrical - Asymmetrical

Bonding Lattice of positive ions with sea of electronsElectrostatic forces attraction bet +ion with electron

Lattice of positive and negative ionsElectrostatic forces attraction bet +ion with -ion

Giant covalent throughout 3D

structure.

Within molecule Within molecule Within molecule-strong covalent - strong covalent - strong covalentBetween molecule Between molecule Between molecule-weak intermolecular - weak intermolecular - weak intermolecular-VDF - VDF - VDF

- Dipole-dipole - Dipole -dipole- H2 bonding

PhysicalPropertyState

Solid(Non volatile)

Solid(Non volatile)

Solid(Non volatile)

Liq/Gas Liq/Gas Liq/Gas(Volatile) (Volatile) (Volatile)

MeltingPoint

HIGH HIGH VERY HIGH Very Low Very Low Very Low

Conduct Good Conductor-free moving electron

Good conductor-free moving ions in molten/aq state

Poor conductor- Diamond, SiO2Semiconductor- Graphite, C60Good conductor- Graphene

Poor conductor Poor conductor Poor conductor

Solubility Insoluble Soluble in polar solvent

Insoluble Soluble in polar Soluble in non polar Soluble in polar solventsolvent solvent

Sea electrons +ve / -ve ions

Strong CovalentMetallic Bonding Ionic Bonding

CI CI

CI CI

CICI....

Between

moleculeWithin

molecule

....

Between

molecule

Within

moleculeH2 Bonding

Carbon atoms

Silicon atoms