ib chemistry on allotrope of carbon, graphene, alloy and metallic bonding

http://lawrencekok.blogspot.com

Prepared by Lawrence Kok

Tutorial on Allotropes of Carbon, Metallic Bonding, properties of graphene and alloys.

Allotropes of Carbon Element exist in different form/physical state

Diamond Fullerene, C60

GrapheneGraphite

Bond to 4 C atoms

Bond to 3 C atoms

Bond to 3 C atoms

…



• 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

• 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)✓

Graphite

Bond to 4 C atoms

Bond to 3 C atoms

Bond to 3 C atoms

…



• 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

…


Diamond Fullerene, C60GrapheneGraphite



Electrical conductivity Electrical conductivity Electrical conductivity Electrical conductivity

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



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 materialreplacing silicon in photovoltaic cell

Drug delivery Transistor/ElectronicTransparent conducting electrode

Click here uses grapheneDrug in graphene


Graphene

• 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

Single sheet conductor Rool into conductive nanotubes


Fullerene, C60Graphene

Electron in hexagonal rings do not delocalized over whole molecule.

6:6 bond shorter than 6:5

6:5 bond bet hexagon and pentagon

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



6:6 bond length bet two hexagonDouble bond

Single bond


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


Graphene touch screen and photovoltaic cell

Click here for application of graphene


Electrical contact photovoltaic cell

Lightest and strongest replacing silicon in photovoltaic cell

6:6 bond length bet two hexagonDouble bond

Single bond

Uses of Carbon Allotropes

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

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)

1 layer thick



sp2 hybridization

graphene

rool into rool into




1 layer thick

Uses of CNT

Strong tubes as space elevator

Filter off salt(desalination)

Drug delivery to body Attachment drug therapeutics



Click here discovery graphene Click here CNT Click here to view

sp2 hybridization

graphene

rool into rool into




Click here TEDtalk graphene

1 layer thick

Uses of CNT

Strong tubes as space elevator

Filter off salt(desalination)

Drug delivery to body Attachment drug therapeutics

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

MetalsMetallic bonding


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

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


Electrostatic force attraction

Metallic Bonding

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


Gp 1

Period 2/3

Metallic Bonding


period 2

period 3

period 2

perio

d 3

Li

Be

B

C

N O F Ne Na

MgAI

Si

P SCI

Melting point across Period 2 and 3


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 ↑

Melting Point

Gp 1

Period 2/3

Metallic Bonding



Electrostatic force attractionMetallic Bonding

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


Melting Point

Gp 1

Period 2/3

Metallic 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




Melting Point

Gp 1

Period 2/3

Metallic Bonding



✓


Number delocalized electrons

Factors affecting Metallic Bonding

Charge on cation Radius cation

Higher ↑ charge cation


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 delocalizedelectron per atom

TWO delocalizedelectron per atom

Radius cation Bigger ↑ Radius cation Smaller ↓

MELTING POINT MELTING POINT


Charge cation smaller ↓ Charge cation Bigger ↑



+1 +2

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

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

Malleable (hammer) Ductile (Stretch)

Mixture of metals in lattice

✓

✓✗

✗

Heating mixture metals together

Alloy cool/solidifies, mechanical property diff from its individual constituents Metals/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

Metals

Structure - crystalline lattice same type atoms

Metals Vs Alloy

Property alloy far superior than its element/metal

Structure - crystalline lattice different atomic sizes

Vs

Malleable (hammer) Ductile (Stretch) Mixture of metals in lattice

Same type atom arrangement

Ductile –Deform/turn to wire

Malleable – Shaped by hammer

Alloy

Mixture metals/non metal

Stronger, harder- enhance qualities than metals

+

✓

Metal + Metal = Alloy

✓

Metals

Structure - crystalline lattice same type atoms

Metals Vs Alloy

Property alloy far superior than 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 atom arrangement

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

✓

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

PhysicalProperty State

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 solvent solvent solvent

Sea electrons +ve / -ve ions

Strong CovalentMetallic Bonding Ionic Bonding

✓

CI CI

CI CI

CICI..........

Betweenmolecule

Withinmolecule

....

Betweenmolecule

Withinmolecule

H2 Bonding

Carbon atoms

Silicon atoms

Acknowledgements

Thanks to source of pictures and video used in this presentation

Thanks to Creative Commons for excellent contribution on licenseshttp://creativecommons.org/licenses/

Prepared by Lawrence Kok

Check out more video tutorials from my site and hope you enjoy this tutorialhttp://lawrencekok.blogspot.com

ib chemistry on allotrope of carbon, graphene, alloy and metallic bonding

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