Neat and Discrete Carbon Nanoparticles Carbon Chemistry

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry2 A space elevator-- a new transport into space? Far Out Application?

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry3 The Proposal: Electric vehicles ascend the ribbon, lifting payloads from Earth to orbiting position A 62,000 mile long thin ribbon composed of an incredibly strong carbon nanotube composite Anchored to a ship The ribbon is connected to a massive counterweight on the other end that extends into space Far Out Application?

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry4 Why haven’t we already built a space elevator? Answer: No materials were available that were both strong and light weight enough. Carbon holds the key… Far Out Application?

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry5 What elements on the periodic table are most likely to form discrete nanoparticles? Those that form covalent bonds, elements to the right of the transition metals (groups 13 through 16) Why? These elements form covalently bonded molecules with specific geometry. The central atom in these molecules form a relatively small number of bonds to neighboring atoms. Review: Carbon Chemistry

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry6 Characteristics of discrete nanoparticles: covalent bonding non-extendable three-dimensional individual “gigantic” molecules Review: Carbon Chemistry

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry7 Let’s focus our attention mostly on discrete nanoparticles made from Carbon Review: Carbon Chemistry

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry8 How many bonds does carbon always form? Four These can be: What is carbon’s electron orbital diagram? two single bonds and one double bond one single bond and one triple bond four single bonds two double bonds Review: Carbon Chemistry

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry9 Four single bonds Tetrahedral with bond angles of approximately 109º. C Two single bonds and one double bond Planar with 120º bond angles. C One single bond and one triple bond Linear with 180º bond angles. C =C==C= Two double bonds Linear with 180º bond angles. Review: VSEPR Theory

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry10 Allotropes are one of two or more forms of an element in the same physical state. What are the common allotropes of carbon? GraphiteDiamond What are Allotropes?

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry11 How are the carbon atoms arranged in diamond? Each interior carbon is covalently bonded to four others in a tetrahedron. Diamond

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry12 How are carbon atoms arranged in graphite? arranged in planar layers (sheets) each interior carbon atom is covalently bonded to three others in a hexagonal pattern very weak forces exist between the layers (gray lines in the figure above) the individual layers extend indefinitely in two dimensions Graphite

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry13 Knowing that: 1.carbon always forms four bonds; 2.each carbon atom in graphite is covalently bonded to three other carbon atoms; and 3.the graphite layers are flat... Two single bonds and one double bond C C C C What is the bonding pattern around a given carbon atom in graphite? Graphite

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry14 In the mid 1980s scientists experimented by vaporizing graphite using a laser. A new substance was formed. This is a diagram of the first experiment with graphite. Graphite

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry15 Scientists knew the substance was carbon, but it wasn’t graphite, diamond or individual carbon atoms. They proposed the formula of the material was C 16. How would chemists represent the structure of C 16 ? So, what was it? Nanoparticles

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry16 C 16 fragment – a flat structure that does not contain hydrogen What is wrong with this picture? Hint: Remember, carbon always forms four bonds. Nanoparticles

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry17 The product obtained in the lab was identified by mass spectrometry. The mass spectrum of the product is shown below. The evidence points to the formula C 60 (mass 720 amu). How many carbon atoms did the sample contain? C ??

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry18 Could the structure of C 60 be flat? No – just like the C16 fragment, a planar C 60 structure would also have “dangling bonds” on the outer edges. C 60

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry19 How can you bend a sheet of C 60 to connect the carbon atoms with dangling bonds? Will it work to roll the sheet into a cylinder? So what is the solution? Perhaps the answer can be found by looking at an organic compound. C 60

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry20 Clearly by adding a 5-membered ring, the structure takes on a bowl-like shape with curvature. Aha! Notice that this molecule, corannulene (C 20 H 10 ), possesses a single 5-membered ring in addition to five 6-membered rings. Nanoparticles

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry21 The mystery of C 60 was finally solved. The Nobel Prize in chemistry was awarded in 1996 for this work. It soon became known as a “buckyball” because it resembles the famous architecture of Buckminster Fuller. This material incorporates both 5-membered and 6- membered rings. Buckyball

Neat and Discrete Carbon Nanoparticles: Carbon Chemistry22 1.What are the characteristics of discrete nanoparticles? 2.How does the arrangement of bonds affect the molecular geometry for carbon? 3.Describe the differences in how carbon is arranged in graphite vs. diamond? 4.How might carbon nanoparticles be useful? Making Connections