![]() The same concept can be applied to any of the straight chain alkane names provided in the table above.There are a few types of atoms that can be a part of a plant one day, an animal the next day, and then travel downstream as a part of a river’s water the following day. The removal of this hydrogen results in a stem change from -ane to -yl. An alkyl group is formed by removing one hydrogen from the alkane chain and is described by the formula C nH 2n +1. It is the bonds only that are being drawn out, and it is understood that there are carbon atoms (with three hydrogens attached!) at the terminal ends of the structure.Īlkanes can be described by the general formula C nH 2n +2. Note also that two lines are sufficient to represent three carbon atoms. If it makes two explicit bonds, there are two hydrogens implicitly attached, etc. For example, if the carbon atom makes only one explicit bond, there are three hydrogens implicitly attached to it. Whenever an insufficient number of bonds to a carbon atom are specified in the structure, it is assumed that the rest of the bonds are made to hydrogens. Since, in the absence of double or triple bonds, carbon makes four bonds total, the presence of hydrogens is implicit. Note that there is no representation of hydrogens in a skeletal structure. Only the bonds between carbons have been drawn, and these have been drawn in a "zig-zag" manner. Consider the following representations of the molecule propane:įigure 2: Full structure of propane and skeletal structure of propane ![]() This is because in the tetrahedral geometry all bonds point as far away from each other as possible, and the structure is not linear. In the case that the molecule contains just single bonds (sp 3 bonds), these bonds are drawn in a "zig-zag" fashion. Individual carbon and hydrogen atoms are not drawn, and bonds to hydrogen are not drawn. In a skeletal structure, only the bonds between carbon atoms are represented. In organic chemistry, hydrocarbons can be represented in a shorthand notation called a skeletal structure. In drawing hydrocarbons, it can be time-consuming to write out each atom and bond individually. The hydrogen connected by a solid wedge points out of this plane toward the viewer, and the hydrogen connected by the dashed wedge points behind this plane and away from the viewer. In the above drawing, the two hydrogens connected by solid lines, as well as the carbon in the center of the molecule, exist in a plane (specifically, the plane of the computer monitor / piece of paper, etc.). Consider the following representation of the molecule methane:įigure 1: Two dimensional representation of methane In order to represent the tetrahedral geometry in two dimensions, solid wedges are used to represent bonds pointing out of the plane of the drawing toward the viewer, and dashed wedges are used to represent bonds pointing out of the plane of the drawing away from the viewer. The other two bonds point in back or in front of this plane. In the tetrahedral geometry, only two bonds can occupy a plane simultaneously. Recall that when carbon makes four bonds, it adopts the tetrahedral geometry. n-hexane is a neurotoxin while its branched-chain isomers are not. Although this is not strictly necessary, the usage is still common in cases where there is an important difference in properties between the straight-chain and branched-chain isomers: e.g. Straight-chain alkanes are sometimes indicated by the prefix n- (for normal) to distinguish them from branched-chain alkanes having the same number of carbon atoms. ![]() Hence, C 5H 12 is called pentane, C 6H 14 is called hexane, C 7H 16 is called heptane and so forth. C 4H 10 = butane = four hydrogen-saturated carbonsĪlkanes with five or more carbon atoms are named by adding the suffix -ane to the appropriate numerical multiplier, except the terminal -a is removed from the basic numerical term.C 3H 8 = propane = three hydrogen-saturated carbons. ![]()
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