revision_1_2-1 - ORGANIC CHEMISTRY CAB 1013 Revision...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
ORGANIC CHEMISTRY CAB 1013
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Revision (Chapter 1&2) Structural Theory - Valency: atoms in organic compounds form a fixed number of bonds - Carbon can form one or more bonds to other carbons
Background image of page 2
3 Isomers Isomers are different molecules with the same molecular formula Many types of isomers exist Example Consider two compounds with molecular formula C 2 H 6 O These compounds cannot be distinguished based on molecular formula; however they have different structures The two compounds differ in the connectivity of their atoms
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Chemical Bonds: The Octet Rule Octet Rule Atoms form bonds to produce the electron configuration of a noble gas (because the electronic configuration of noble gases is particularly stable) For most atoms of interest this means achieving a valence shell configuration of 8 electrons corresponding to that of the nearest noble gas Atoms close to helium achieve a valence shell configuration of 2 electrons Atoms can form either ionic or covalent bonds to satisfy the octet rule
Background image of page 4
5 Electronegativity Electronegativity is the ability of an atom to attract electrons It increases from left to right and from bottom to top in the periodic table (noble gases excluded) Fluorine is the most electronegative atom and can stabilize excess electron density the best
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 Ionic Bonds - When ionic bonds are formed atoms gain or lose electrons to achieve the electronic configuration of the nearest noble gas In the process the atoms become ionic - The resulting oppositely charged ions attract and form ionic bonds Lithium loses an electron (to have the configuration of helium) and becomes positively charged Fluoride gains an electron (to have the configuration of neon) and becomes negatively charged The positively charged lithium and the negatively charged fluoride form a strong ionic bond
Background image of page 6
7 Covalent Bonds Covalent bonds occur between atoms of similar electronegativity (close to each other in the periodic table) Atoms achieve octets by sharing of valence electrons Molecules result from this covalent bonding Valence electrons can be indicated by dots (electron-dot formula or Lewis structures) but this is time-consuming The usual way to indicate the two electrons in a bond is to use a line (one line = two electrons)
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
8 Resonance Often a single Lewis structure does not accurately represent the true structure of a molecule The real carbonate ion is not represented by any of the structures 1,2 or 3 Experimentally carbonate is known not to have two carbon-oxygen single bonds and one double bond; all bonds are equal in length and the charge is spread equally over all three oxygens
Background image of page 8
9 The real carbonate ion can be represented by a drawing in which partial double bonds to the oxygens are shown and partial negative charge exists on each oxygen The real structure is a resonance hybrid or mixture of all three Lewis structures Double headed arrows are used to show that the three Lewis
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/08/2009 for the course CHEMICAL 11189 taught by Professor Dr.azmi during the Spring '09 term at International University in Germany.

Page1 / 47

revision_1_2-1 - ORGANIC CHEMISTRY CAB 1013 Revision...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online