Types of Bonds
All bonds, in and around an atom, fall into two categories – Intermolecular and Intramolecular bonds. These two categories can then be broken further down to three subcategories;
Intramolecular
Chemical Bonds – A chemical bond is a link between atoms via the sharing of electrons through overlapping orbitals. A typical chemical bond will contain two electrons and one electron will usually originate from each of the atoms involved. The electrons shared need not necessarily originate from both of the atoms and neither must the number of atoms involved be two, 3-centred two electron bonds exist.
This type of bond is the strongest of all three bonds and thus requires the most energy input to break - ranging from 151 KJ/mol (I-I) to 945 KJ/mol (N≡N). There are two types of chemical bonds; Ionic and covalent bonds.
Intermolecular
Van-Der-Waals – This type of bond is the weakest of the three bonds and originates from the fact that electrons are constantly in movement. Because they do not all move in unison, ‘wells’ where there is a net negative and positive charge appear. These opposite charges then attract each other and albeit weakly congregate molecules together. As these bonds rely on electrons, the greater the number of electrons in a molecule – and thus the size of the molecules themselves – the greater these forces are. These forces may then be split into two sub categories; London Dispersive forces and dipole-dipole interactions.
Hydrogen Bonds – These bonds are a strong intermolecular forces, much greater than Van-Der-Waals and yet is relatively small in comparison to a chemical bond. A hydrogen bond can range from about 5-35 KJ/mol. ‘Clusters of Molecules are held together in specific orientati...
... middle of paper ...
...ick F.H.C., A Structure for Deoxyribose Nucleic Acid, Nature 171, 737-738 (1953)
7. Lehninger, Nelson, D.L, Cox, M. M, Principles of Biochemistry, W. H. Freeman and Company, U.S.A, 2013, Pages 292-293
8. Jeffrey, G.A., An Introduction to Hydrogen Bonding, Oxford University Press, New York, 1997, Page 185
9. I. David Brown, The Chemical Bond in Inorganic Chemistry, Oxford University Press, New York, 2002 page 27
10. I. David Brown, The Chemical Bond in Inorganic Chemistry, Oxford University Press, New York, 2002 page 77
11. Desiraju, G.R., Steiner, T., The Weak Hydrogen Bond, Oxford University Press, New York, 1999, Pages 4
12. Friebolin, H. Basic One and Two Dimensional NMR Spectroscopy, 5th ed. Federal Republic of Germany, 2011, Pages 59-60
13. Friebolin, H. Basic One and Two Dimensional NMR Spectroscopy, 5th ed. Federal Republic of Germany, 2011, Page 335
2. Cooper, M. M., Cooperative Chemistry Laboratory Manual, McGraw-Hill: New York, NY, 2009, p. 60.
Hydrogen is a diatomic element that is in a gaseous form at room temperature. Its most identifying characteristic is the fact that it is highly explosive. It is the lightest element in the world, and has a lifting power of 8% more than that of helium. Hydrogen was used in airships and zeppelins for more than 20 years during the beginning of the 20th century. This practice stopped abruptly after the German airship Hindenburg disaster over New Jersey. It is used in fuel cells to create electricity, and to power cars and planes. Liquid hydrogen is mixed with liquid oxygen to form a cryogenic liquid that is burnt in Solid Rocket Boosters to power the space shuttle. Hydrogen is used to fill weather balloons because of its superb lifting power.
middle of paper ... ... The Web. 22 Feb. 2014. http://www.chemheritage.org/discover/online-resources/chemistry-in-history>.
Scibd. N.p. Web. 17 Mar 2014. Beller, Michele.
After performing the second TLC analysis (Figure 4), it was apparent that the product had purified because of the separation from the starting spot, unlike Figure 3. In addition, there was only spot that could be seen on the final TLC, indicating that only one isomer formed. Since (E,E) is the more stable isomer due to a less steric hindrance relative to the (E,Z) isomer, it can be inferred that (E,E) 1,4-Diphenyl-1,3-butadiene was the sole product. The proton NMR also confirmed that only (E,E) 1,4-Diphenyl-1,3-butadiene formed; based on literature values, the (E,E) isomer has peaks between 6.6-7.0 ppm for vinyl protons and 7.2-7.5 ppm for the phenyl protons. Likewise, the (E,Z) isomer has vinyl proton peaks at 6.2-6.5 ppm and 6.7-6.9 ppm in addition to the phenyl protons. The H NMR in Figure 5 shows multiplets only after 6.5 ppm, again confirming that only (E,E) 1,4-Diphenyl-1,3-butadiene formed. In addition, the coupling constant J of the (E,E) isomer is around 14-15 Hz, while for the (E,Z) isomer it is 11-12 Hz. Based on the NMR in Figure 5, the coupling constant is 15.15 Hz, complementing the production of (E,E)
... middle of paper ... ... Brown, P., & Levinson, S. C. (1987).
The 1H NMR spectrum shows that there are 18 protons in 11 different proton environments. This fits with the Diels-Alder reaction taking place a...
This chemistry book report is focus on a book called “Napoleon's buttons: How 17 molecules changed history” by Penny Le Couteur and Jay Burreson. The publisher of this book is Tarcher Putnam, the book was published in Canada on 2003 with 17 chapters (hey the number match the title of the book!) and a total of 378 pages. The genre of this book is nonfiction. “Napoleon's Buttons” contain a fascinating story of seventeen groups of molecules that have greatly changed the course of history and continuing affect the world we live in today. It also reveal the astonishing chemical connection among some unrelated events, for example: Chemistry caused New Amsterdamers to be renamed New Yorkers and one little accident of detonating cotton apron in a minor housekeeping mishap lead to the development of modern explosives and the founding of the movie industry.
The link between the number of carbon atoms in a fuel with the amount of energy it releases. Alcohols generally belong to compounds whose molecules are based on chains of carbon atoms. They usually contain one oxygen atom, which is joined to a carbon atom by a singular bond. This makes them different from other compounds.
Sootin, Harry, and Gustav Schrotter.Robert Boyle : founder of modern chemistry. New York: F. Watts, 1962. Print.
Levy, Joel. The Bedside Book Of Chemistry. Vol. 1. Millers Point: Pier 9, 2011. 34-84. 1 vols. Print.
David and John Free. (26 Nov 2006). MadSci Network: Chemistry. Retrieved on March 6, 2011, from http://www.madsci.org/posts/archives/2007-02/1171045656.Ch.r.html
In chemistry there are a lot of elements on the periodic table. One of the elements is hydrogen. Hydrogen the first element in the periodic table it is colorless, combustible and lightest of all gases. It was first artificially produced in the early 16th century by Henry Cavendish. As we know hydrogen can be used as fuel, and the fossil fuel energy has been used in many areas, but human can’t produce the fossil energy fuel by themselves, the more we use, the less we have left, so hydrogen may be used as the most common use fuel instead of gases in the future, it is not only used as fuel but also extensively used in different areas, such as industry, agriculture, medicine, and research.
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/
From these properties of bonds we will see that there are two fundamental types of bonds--covalent and ionic. Covalent bonding represents a situation of about equal sharing of the electrons between nuclei in the bond. Covalent bonds are formed between atoms of approximately equal electronegativity. Because each atom has near equal pull for the electrons in the bond, the electrons are not completely transferred from one atom to another. When the difference in electronegativity between the two atoms in a bond is large, the more electronegative atom can strip an electron off of the less electronegative one to form a negatively charged anion and a positively charged cation. The two ions are held together in an ionic bond because the oppositely charged ions attract each other as described by Coulomb's Law.