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Expressing resonance when drawing Lewis structures may be done either by drawing each of the possible resonance forms and placing double-headed arrows between them or by using dashed lines to represent the partial bonds (although the latter is a good representation of the resonance hybrid which is not, formally speaking, a Lewis structure).
Lewis structures (or "Lewis dot structures") are flat graphical formulas that show atom connectivity and lone pair or unpaired electrons, but not three-dimensional structure. This notation is mostly used for small molecules. Each line represents the two electrons of a single bond. Two or three parallel lines between pairs of atoms represent ...
Draw the structure, and save it as a ChemDraw file. If you drew the structure before applying any settings, then you need to select the object, open the "Object" menu and choose "Apply document settings from → ACS Document 1996". Then save it as a PNG file, to be read by an image editor such as GIMP or IrfanView (see below for details).
The skeletal formula of hexane, with carbons number one and three labelled The Lewis structure of hexane, for reference The 3d ball representation of hexane, with carbon (black) and hydrogen (white) shown explicitly. It does not matter which end of the chain one starts numbering from, as long as consistency is maintained when drawing diagrams.
The Simplified Molecular Input Line Entry System (SMILES) is a specification in the form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules.
Detection of structures, text, and arrows, and their automatic placement; Can automatically draw rings and other structures - has all standard amino acids and nucleic acids in a built-in library; Retrieval of structures from a network database based on CAS number, formula, or name; Retrieval of information on a molecule based on a drawing
An intermediate state where only one corner is shared (structure B) was also postulated by Lewis. Double bonds are formed by sharing a face between two cubic atoms. This results in sharing four electrons: Triple bonds could not be accounted for by the cubical atom model, because there is no way of having two cubes share three parallel edges.
EWGs enhance the Lewis acidity, making compounds more reactive as Lewis acids. For example, fluorine is a stronger electron-withdrawing substituent than methyl, resulting in an increased Lewis acidity of boron trifluoride relative to trimethylborane. Electron-withdrawing groups also tend to reduce Lewis basicity. [3]