In Reading a Line Drawing How Do You Know Where Atoms of These Elements Are in the Structure
4.8: Line drawings
- Folio ID
- 40300
Other kinds of drawings
Line drawings
Lewis structures can tell us a lot about how atoms come together to make molecules. They can likewise be cumbersome, especially if nosotros are dealing with very big molecules. Cartoon a line instead of a pair of dots for bonding pairs of electrons makes it easier to depict structures. In that location are other abbreviations that are helpful in some situations.
Because organic chemical science is based on the compounds of carbon, we would have to draw the letter C over and over over again unless we had a shortcut. In line structures (likewise sometimes called skeletal drawings), we drop the label "C" for the carbon atoms. Anytime there is a joint between ii bonds (drawn as a vertex in a zig-zag line), the atom attached to that bail is assumed to exist a carbon unless written otherwise.
The atom at the end of a zig-zag line would also be a carbon, unless it is explicitly written as some other cantlet.
Taken fifty-fifty further, we will omit the hydrogens from our structures, since the compounds of carbon nigh always contain hydrogen also. Since we know carbon has a valence of four, we always know how many hydrogen atoms are fastened to each carbon in order to achieve that valence. A carbon with ii bonds fatigued in must have ii hydrogens on it. A carbon with only i bond drawn to it must have three hydrogens.
Note that the hydrogens are non normally omitted if they are fastened to heteroatoms (atoms other than carbon, such as oxygen or nitrogen).
You will also annotation that alone pairs are frequently left out when we employ line structures, and then you will have to add together them dorsum in to think about Lewis structures. Adding the lone pairs back to the heteroatoms in line structures is a good habit to go into, because later in the grade we will be very concerned with keeping rails of where all the electrons are.
Below is a summary, showing the human relationship between Lewis/Kekule structures, line structures and condensed formulae for a few different compounds.
Recollect, in phenol, the hydrogen attached to oxygen was labeled in the line construction. Sometimes in that location are exceptions in line structures, in which atoms that yous might not think most labeling usually do get labels. The most common exceptions are shown below.
Trouble 4.8.1.
Translate the following condensed formulae into line drawings.
a) CH3CHtwoNHCH2CH3 b) CHthreeCHFCH2CHiiCHiiCl
c) CHtwoCHOCHiiCHthree d) CHiiiCHClCH2SCHtwoCH3
Problem 4.viii.two.
Interpret the following structures into condensed formula.
Problem 4.eight.3.
Try filling in the missing line drawing, Lewis / Kekule structures or condensed formulae in each line of the tabular array beneath.
Source: https://chem.libretexts.org/Courses/Mount_Royal_University/Chem_1201/Unit_4%3A_Chemical_Bonding_II_-_Advanced_Bonding_Theories/4.08%3A_Line_drawings
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