What is a sigma bond? Pi bond?
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Sigma Bond:\n     A type of bond between two atoms in which two partially filled atomic orbitals overlap in such a way that the probability of finding an electron is maximum around the line joining the two nuclei.\n                           OR\n     Sigma bonds are those bonds between atoms in a molecule that exhibit orbital hybridization\nPi Bond:\n     A type of bond which is formed by the sideways overlap of two half filled co-planar p-orbitals in such a way that the probability of find finding an electron is maximum perpendicular to the line joining the two nuclei.\n                          OR\n    Pi bonds are those bonds between two atoms in a molecule that do not exhibit orbital hybridization
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E(sigma) means summation.\nIf it is backwards, then it means "there exists"
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These are three greek letters.\nsigma = s\nlamda = l\nphi = f \n \nThats all I found:\n\n(Sigma Phi Delta) is a unique professional international engineering fraternity. As such, the fraternity only admits male engineering students. There are two other Professional Engineering fraternities, one is Sigma Phi Delta's Sister Sorority Alpha Omega Epsilon and admits women, and the other one is Triangle Fraternity and admits not just engineering students, but architecture, and science students as well.\n\n--------------------------------------------------\nList of Chapters (active and inactive)\n\n(Sigma) Chapter - California State University, Located in Long Beach, CA \n\n(Lambda) Chapter - Indiana Technical College, Located in Fort Wayne, IN \n\n(Phi) Chapter - South Dakota State University, Located in Brookings, South Dakota
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Well, whether the bond is a single, double, or triple bond also determines the hybridization of the sigma bond.\n\nFor example, if you have two pi bonds in addition to the sigma bond, the sigma bond is an sp hybridized bond because two p orbitals on each atom are consumed making the two extra pi bonds.\n\nIf you have one pi bond in addition to the sigma bond, the sigma bond is an sp2 hybridized bond because only one p orbital on each atom is consumed to make the single pi bond.\n\nIf no p orbitals are used to make pi bonds all p orbitals are available to make the sp3 sigma bonds.\n\nJust count the number of bonds.  If one the sigma bond is sp3.  If two the sigma bond is sp2.  If three bonds, the sigma bond is sp.
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1. Covalent Bonds\n2. Ionic Bonds\n3. Hydrogen Bonds
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This is kinda hard to draw on here...\n......_\nK--Br|\n......_\n\nThe lines around Br represent 2 electrons, and the -- represents a bond...ignore the periods
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It's covalent bonding between the carbon atoms.  The whole diamond can be considered one molecule actually because of the ability of carbon atoms to covalently bond to each other.
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They all vary, depending on the size of the atoms involved.  Covalent bonds distance is defined as 1/2 the distance between the two atoms radii.  As you can see this is difficult to determine if they are not the same atom.  Most bond lengths are estimated based on similar structures.
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your formula refers to several different structures which of course would give different NMR spectra. It could be 2-bromo-X-methylpyridine where X is the 3,4,5 or 6 position or Bromoaniline, with the various positional isomers. If you don't know the name go to the sigma website and find the structure/name (it may even have the NMR).
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Ionic bond, hydrogen bonds, covalent bond, ionic interactions, van der waals interaction, non-polar interaction ... the list goes on.\n\nA bit more on covalent bonds:\nThere are sigma and pi covalent bonds, mainly. Pi bonds are usually the double bonds, while sigma are single bonds. Pi bonds can have resonance!\n.\nAlso there are often non-bonding electrons and anti-bonding electrons in molecules, but they aren't really "bonds"\n.\nCheers.\n.\nP.S.: If you share "chemistry" with a girl / boy you could also call that a "chemical bond"! He he he he.
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That's an easy one... Ha Ha!\n\nA pi-acid is an acid that accepts electron density into it's pi-orbital.\n\nThe term, pi molecular orbital, is a symmetry designation.  A pi molecular orbital is antisymmetric with respect to a defining plane containing at least one atom (ie. the molecular plane of ethene).  A sigma molecular orbital is symmetric with respect to the same plane.  The terms are used both in this rigorous sense (for orbitals encompassing the entire molecule) and also for localized two-centre orbitals or bonds.  In the case of two-centre bonds, a pi bond has a nodal plane that includes the internuclear bond axis, whereas a sigma bond has no such nodal plane.\nInteraction between orbitals of different symmetries (with respect to the same defining plane) is forbidden!\n\n-- pi-acids or pi-bases usually apply to  Organometallic Chemistry and Molecular Orbital Theory.
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advantages:\nYou can get a general idea of the shape of the molecule\nit gives a 3d representation of the molecule\n\ndisadvantages:\nif the molecule has double/triple bonds it doesnot give an accurate representation of sigma and pi bonds
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www.visionlearning.com/library/module_viewer.php?mid=55 - 66k \n\nwww.biology.arizona.edu/biochemistry/ tutorials/chemistry/page2.html - 7k - \n\nhttp://en.wikipedia.org/wiki/Chemical_bond
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amino acids joined by peptide bonds
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(1-A)*lsun/sigma*16*pi*d^2= 1-0.50*3.9*10^26/5.67*10^-8*16...\n= 1.95*10^26/1.507*10^7= 1.293*10^19= 59966.2K you were close it was 59966.3K.      ;-).
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Covalent bond: bond in which one or more pairs of electrons are shared by two atoms.\n\nIonic bond: bond in which one or more electrons from one atom are removed and attached to another atom, resulting in positive and negative ions which attract each other.\n\nOther types of bonds include metallic bonds and hydrogen bonding. The attractive forces between molecules in a liquid can be characterized as van der Waals bonds.
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If the difference in the electronegativity between the two elements is less than 1.67, the bond will be covalent.\n\nNote: As to the statement that electronegative atoms don't form covalent bonds, that's nonsense.  ALL atoms are electronegative to some extent.  Just go look up the electronegativity series in any general chem. text.  Or check out this:\nhttp://dbhs.wvusd.k12.ca.us/webdocs/Bonding/Electroneg-Bond-Polarity.html