Structure of Matter

Atomic  Macro

Draft for first version of Mendeleev's periodic table (17 February 1869).

“I began to look about and write down the elements with their atomic weights and typical properties, analogous elements and like atomic weights on separate cards, and this soon convinced me that the properties of elements are in periodic dependence upon their atomic weights.” --Mendeleev, Principles of Chemistry, 1905, Vol. II

Atomic Mass and Moles

= number of protons (= number of electrons) = number of protons + neutrons (averaged over different isotopes) (1 u = x kg)

Isotopes isotopes = same number of protons, different number of neutrons Similar chemical properties, quite different nuclear properties!

Energy and Bond Formation

Comparison of Bonding

Give up electronsAcquire electrons Adapted from Fig. 2.7, Callister 6e. (Fig. 2.7 is adapted from Linus Pauling, The Nature of the Chemical Bond, 3rd edition, Copyright 1939 and 1940, 3rd edition. Copyright 1960 by Cornell University. Ionic Bonding

Covalent Bond Shared electrons One electron from an orbital in atom A One electron from an orbital in atom B They become ‘spin paired’

Molecules with nonmetals Molecules with metals and nonmetals Elemental solids (RHS of Periodic Table) Compound solids (about column IVA) Adapted from Fig. 2.7, Callister 6e. (Fig. 2.7 is adapted from Linus Pauling, The Nature of the Chemical Bond, 3rd edition, Copyright 1939 and 1940, 3rd edition. Copyright 1960 by Cornell University. Covalent Bonding 3.5 Prevalent in ceramics and polymers

Arises from a sea of donated valence electrons (1, 2, or 3 from each atom). Primary bond for metals and their alloys  high electrical conductivity. Why? Adapted from Fig. 2.11, Callister 6e. Metallic Bonding

Secondary Bonds Bonds between atoms without electron transfer or sharing Low bonding energies Hydrogen Bonds –Water molecules are polar Van der Waals Bonds –Attraction of opposite charges Electron density fluctuates around an atom Instantaneous dipole-induced dipole interaction

Hydrogen Bonds in H 2 O O HH + + -

O HH O HH + + -

Graphite – Van der Waals Bonds

Graphite

Graphite

Soft and slipperyMany strong covalent bonds holding the structure together but only in 2 dimensions. The layers are free to slide easily over one another. Graphite powder is used as a lubricant. BrittleAll of the bonds are directional within a layer and stress across a layer will tend to break them. Graphite rods used for electrolysis easily break when dropped. Electrical conductorOnly three of the valence (outer shell) electrons are used in sigma bonding. The other electron is in a 'p' orbital which can overlap laterally with neighbouring 'p' orbitals making giant molecular pi orbitals that extend over the whole of each layer. Electrons are free to move within these delocalised pi orbitals. Insoluble in water.There are only very weak Van der Waal's attractions between the carbon atoms and the water molecules whereas the carbon atoms are bonded very tightly to one another. Very high melting pointMany strong covalent bonds holding the layers together - it requires massive amounts of energy to pull it apart Graphite

Diamond

Diamond

HardMany strong covalent bonds holding the structure together. BrittleAll of the bonds are directional and stress will tend to break the structure (In a malleable substance, such as for example a metal, the bonding is non-directional and can still act if the particles are displaced with respect to one another). InsulatorAll of the valence (outer shell) electrons are used in bonding. The bonds are sigma and the electrons are located between the two carbon nuclei being bonded together. None of the electrons are free to move Insoluble in water.There are only very weak Van der Waal's attractions between the carbon atoms and the water molecules whereas the carbon atoms are bodned very tightly to one another. Very high melting pointMany strong covalent bonds holding the structure together - it requires massive amounts of energy to pull it apart Diamond

Diamond

Properties & Applications Electrical Mechanical Thermal Storage Nanocarbon

Discovered in 1985 Nobel prize Chemistry 1996 Curl, Kroto, and Smalley Fullerenes

Architect: R. Buckminster Fuller Epcot center, Paris

Buckyballs C facets (12 pentagons and 20 hexagons) C 70, C 76, and C 84

Buckyballs C facets (12 pentagons and 20 hexagons)

Bucky Balls Symmetric shape → lubricant Large surface area → catalyst High temperature (~750 o C) High pressure Hollow → caging particles

Buckyballs Forms a crystal by weak van der Waals force Superconductivity - K 3 C 60 : 19.2 K - RbCs 2 C 60 : 33 K Kittel, Introduction to Solid State Physics, 7the ed

Buckyballs Forms a crystal by weak van der Waals force Superconductivity - K 3 C 60 : 19.2 K - RbCs 2 C 60 : 33 K

Soft and slipperyFew covalent bonds holding the molecules together but only weak Vander Waals forces between molecules. BrittleSoft weak crystals typical of covalent substances Electrical InsulatorNo movement of electrons available from one molecule to the next. The exception could be the formation of nano-tubes that are capable of conducting electricity along their length. These are the subject of some experiments in micro electronics Insoluble in water.There are only very weak Van der Waal's attractions between the carbon atoms and the water molecules whereas the carbon atoms are bonded very tightly to one another in the molecules. Low Melting Point SolidsTypical of covalent crystals where only Van der Waal's interactions have to be broken for melting. Buckyballs

Carbon Nanotubes (CNT) Like graphite but all coiled up Typically 10 Angstroms in diameter Can be electrically conductive or semiconducting SWNT and MWNT –Composites, transistors, hydrogen storage Courtesy of and ©Copyright Professor Charles M. Lieber GroupProfessor Charles M. Lieber Group

Nanotube

The "armchair" type has the characteristics of a metal The "zigzag" type has properties that change depending on the tube diameter The "spiral" type has the characteristics of a semiconductor Armchair Zigzag Spiral

Nanotube Zheng et al. Nature Materials 3 (2004) 673. SWCNT – 1.9 nm Diameter: as low as 1 nm Length: μm to cm High aspect ratio: → quasi 1D solid

Nanotube Intro Video Earth and sky: Properties of Nanotubes

Nanotube Stats Current capacity Carbon nanotube 1 GAmps / cm 2 Copper wire 1 MAmps / cm 2 Thermal conductivity Comparable to pure diamond (3320 W / m. K) Temperature stability Carbon nanotube 750 o C (in air) Metal wires in microchips 600 – 1000 o C Caging May change electrical properties → can be used as a sensor

Nanotubes Carbon nanotubes are the strongest known material. Young Modulus (stiffness): Carbon nanotubes 1250 GPa Carbon fibers 425 GPa (max.) High strength steel 200 GPa Tensile strength (breaking strength) Carbon nanotubes GPa Carbon fibers GPa High strength steel ~ 2 GPa Elongation to failure : ~ % Density: Carbon nanotube (SW) 1.33 – 1.40 gram / cm 3 Aluminium 2.7 gram / cm 3

Synthesis of Carbon Nanotubes IFW-Dresden Carbon Nanotubes Synthesis of Carbon nanotube lerene%20Fullereno%20Buckyballhttp:// lerene%20Fullereno%20Buckyball Growth of Carbon nanotube

Stain, static, and liquid-resistant fabrics

Water Resistant Coatings

Carbon Fiber A 6 μm diameter carbon filament (running from bottom left to top right) compared to a human hair.

Sports Equipment

CNT Carbon Nanotube Opti-Flex composite handle technology, provids maximum handle flex-three times greater than aluminum

Carbon Nanotube/Cement Composite Systems In concrete, they increase the tensile strength, and halt crack propagation.

The Space Elevator

Space Elevator NOVA space elevator intro mode=related&searchhttp:// mode=related&search 2 minute space elevator intro Space Elevator Competition: USST's First Place Climb ch=space-elevator%20turbo%20crawlerhttp:// ch=space-elevator%20turbo%20crawler

CNT light bulb filament: alternative to tungsten filaments in incandescent lamps The average efficiency is 40% higher than that of a tungsten filament at the same temperature (1400–2300 K).

Nano Radio

When a radio wave of a specific frequency impinges on the nanotube, it begins to vibrate vigorously. An electric field applied to the nanotube forces electrons to be emitted from its tip. This electrical current may be used to detect the mechanical vibrations of the nanotube, and thus listen to the radio waves.

Nanotube Radio &feature=relatedhttp:// &feature=related

Carbon Nanotube Electronics Carbon nanotube in microchip e=related&search=Nanotubehttp:// e=related&search=Nanotube Customized Y-Shaped Nanotubes Transistors – the active component of virtually all electronic devices, are what we refer to as electronic switching devices. In a transistor, a small electric current can be used to control the on/off of a larger current.

Semiconducting CNTs have been used to fabricate field effect transistors (CNTFETs). The electron mean free path in SWCNTs can exceed 1 micron (this is very large) therefore it is projected that CNT devices will operate in the frequency range of hundreds of GHz.

Kavli Institute Delft SEM image of superconducting transistors

CNT-FED Professor George Lisensky

CNT-FED Carbon nanotubes can be electrically conductive and due to their small diameter of several nanometers, they can be used as field emitters with extremely high efficiency for field emission displays (FED). The principle of operation resembles that of the cathode ray tube, but on a much smaller length scale.

Bucky Paper A thin sheet made from nanotubes that are 250 times stronger than steel and 10 times lighter that could be used as a heat sink for chipboards, a backlight for LCD screens or as a faraday cage to protect electrical devices

Warwick ICAST

Hydrogen Storage Carbon nanotubes covered in titanium atoms provide a very efficient method for storing hydrogen.

'Artificial muscles' made from nanotubes "Artificial muscles" have been made from millions of carbon nanotubes. Like natural muscles, providing an electrical charge causes the individual fibers to expand and the whole structure to move.

Bone cells grown on carbon nanotubes Researchers at the University of California, Riverside have published findings that show, for the first time, that bone cells can grow and proliferate on a scaffold of carbon nanotubes. Scientists found that the nanotubes, 100,000 times finer than a human hair, are an excellent scaffold for bone cells to grow on. carbon-nanotubes/

Nano SQUID A SQUID is a superconducting interferometer device. SQUID devices can be used to monitor infinitesimally small magnetic fields or currents. The originality of this work, is to use gate-tunable carbon-nanotubes (CNT) for the Josephson junctions. The device combines features of single electron transistors with typical properties of a SQUID interferometer. The gate tunability of the CNT junctions enhance the sensitivity of the device which can in principle detect the spin of a single molecule.