Electronegativity_tips - electrons spend surrounding each...

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Polar Molecules and Electronegativity in Biology Prepared for Dr. Buskirk’s Bio 311C students by Beckie Symula If you consider all of the atoms on the periodic table, every one has its own electronegativity value (Pauling scale). Electronegativity is just the ability of an atom to attract electrons towards itself in a covalent bond. On the periodic table below, each atom is shown with its assigned electronegativity. The scale ranges from 0.7 to 4, and though there is a real calculation (http://en.wikipedia.org/wiki/Electronegativity/) based upon the different parts of the atom and number of electrons, it's easier to remember basic characteristics and periodic trends : The most electronegative atom is Flourine (F) with a value of 4 (strongly attracts electrons). The least electronegative atom is Francium (Fr) with a value of 0.7. Less electronegative elements are found in the bottom left. More electronegative elements are found in the top right. In covalent bonds (those that share electrons), polarity is determined by the relative amount of time
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Unformatted text preview: electrons spend surrounding each atom's nucleus. If an atom is highly electronegative, it strongly attracts electrons. In a covalent bond, this means all of the electrons (in the outer shell) spend more time around the more electronegative atom. If you subtract the electronegativity values of two atoms and the result is large, it's a polar molecule. If the difference in electronegativity is small, it's non-polar . In biology, the really important atoms/elements are : Hydrogen, Oxygen, Carbon, Nitrogen These are found in all organisms and the key biological molecules (carbohydrates, proteins, nucleic acids and lipids) each contain at least three of them. Therefore, in terms of biology, the highly polar covalent bonds involve some of these 4 atoms. So, which bond is the most polar in biology? (You don't need to know the numbers.) How do you know? Why is the C-H bond (very common in biological molecules) considered non-polar?...
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