How to draw

When first dealing with resonance forms, it s useful to have a set of guidelines that describe how to draw and interpret them. 

Now that we know how to read these drawings, we need to learn how to draw them. Take the following molecule as an example ... 

In this example, we can see that one of the lone pairs on oxygen is coming down to form a bond, and the C=C double bond is being pushed to form a lone pair on a carbon atom. When both arrows are pushed at the same time, we are not violating either of the two commandments. So, let s focus on how to draw the resonance structure. Since we know what arrows mean, it is easy to follow the arrows. We just get rid of one lone pair on oxygen, place a double bond between carbon and oxygen, get rid of the carbon-carbon double bond, and place a lone pair on carbon ... 

Now we have all the tools we need. We know why we need resonance structures and what they represent. We know what curved arrows represent. We know how to recognize bad arrows that violate the two commandments. We know how to draw arrows that get you from one structure to another, and we know how to draw formal charges. We are now ready for the final challenge using curved arrows to draw resonance structures. 

You can almost imagine someone sitting on this structure, as if it were a beach chair. Most students have a difficult time drawing the chair and its substituents correctly. In this section, we will focus on learning how to draw the chair correctly. It is very important, because we cannot move on to see more about chairs until you know how to draw them. 

When you draw the chair sloppily (as so many students do), it makes it impossible to place the substituents correctly on the ring. And that s when you start losing silly points on your exam. So, take the time to practice and learn how to draw it properly. Practice in the space below ... 

Next we need to learn how to draw the equatorial substituents. These are the substituents pointing out toward the sides. There are also six of them. Each one is rawn so at it is parallel to the two bonds from which it is once removed ... 

Now we know how to draw all twelve substituents, but remember that if we draw a line and don t put anything at the end of that line, then this implies a methyl group. So, unless we are referring to dodecamethylcyclohexane (that s 12 methyl groups), we should really draw hydrogen atoms at the end of these lines ... 

Now we need to see how to draw a chair with proper placement of the groups when we are given a regular hexagon-style drawing ... 

It will become very clear that these groups are trans to each other when we leam how to draw the chair after it has flipped to give us a new chair drawing. We will see this in the next section. For now, let s get some practice drawing the first chair correctly. 

Now, let s make sure you know how to draw the substituents. The rules are the same as before. All axial positions are drawn straight up and down, alternating ... 

Imagine that the two brothers are twins. They are identical in every way except one. One of them has a mole on his right cheek, and the other has a mole on his left cheek. This allows you to distinguish them from each other. They are mirror images of each other, but they don t look exactly the same (one cannot be superimposed on top of the other). It is very important to be able to see the relationship between different compounds. It is important to be able to draw enantiomers. Later in the course, you will see reactions where a stereocenter is created and both enantiomers are formed. To predict the products, you must be able to draw both enantiomers. In this section, we will see how to draw enantiomers. 

So we must learn how to draw one enantiomer when we are given the other. When we see the different ways of doing this, we will begin to recognize when compounds are enantiomers and when they are not. 

When we learned how to draw resonance structures, we saw two conunand-ments that we must not violate (1) never break a single bond, and (2) never exceed an octet for second-row elements. When drawing mechanisms, we are trying to understand where the electrons actually moved to break and form bonds. Therefore, it is OK to break single bonds. In fact, it happens in almost every reaction. So when drawing mechanisms there is only one commandment to follow never exceed an octet for second-row elements. 

So let s get practice drawing intermediates. If you look closely at any step of a mechanism, you will see that the arrows tell you exactly how to draw the intermediate. Since you know how to classify every arrow into one of three categories... 

The first half of our story builds up to reactions, and we learn about the characteristics of molecules that help us understand reactions. We begin by looking at atoms, the building blocks of molecules, and what happens when they combine to form bonds. We focus on special bonds between certain atoms, and we see how the nature of bonds can affect the shape and stability of molecules. At this point, we need a vocabulary to start talking about molecules, so we learn how to draw and name molecules. We see how molecules move around in space, and we explore the relationships between similar types of molecules. At this point, we know the important characteristics of molecules, and we are ready to use our knowledge to explore reactions. 

The primary structure of a polypeptide is its sequence of amino acids. It is customary to write primary structures of polypeptides using the three-letter abbreviation for each amino acid. By convention, the structure is written so that the amino acid on the left bears the terminal amino group of the polypeptide and the amino acid on the right bears the terminal carboxyl group. Figure 13-35 shows the two dipeptides that can be made from glycine and serine. Although they contain the same amino acids, they are different molecules whose chemical and physical properties differ. Example shows how to draw the primary stmcture of a peptide. 

We have seen how to draw and write these abstract descriptions, but how can you be sure they accurately represent the code The concepts of abstraction and refinement capture the essential relationship between these descriptions. This chapter is about different forms of abstraction and refinement, and it explains the rules for showing that a more detailed model refines (or conforms to) a more abstract one. 

Have you ever wondered how to draw the structures of compounds For example, compounds such as CCI4, PBr3 or ions such as SO. To draw the structural formulae we will use the Lewis (electron dot) notation. 

The purpose of this exercise is to learn how to draw a probability ellipse from the mean values and covariance matrix, a topic to be further developed in Chapter 4. Na and Cl are incorporated into clouds during evaporation of seawater and are therefore strongly correlated. 

Example The results obtained from the determination of concentration of the standard solutions and measurements of corresponding peak areas with a GC are recorded in Table 3.1 and plotted in Figure 3.3 where the former is represented along the x-axis and the latter along the y-axis. How to draw the best straight line through all these points ... 

In this unit, you will study a variety of organic compounds. You will learn how to name them and how to draw their structures. You will also learn how these compounds react, and you will use your knowledge to predict the products of organic reactions. In addition, you will discover the amazing variety of organic compounds in your body and in your life. 

How To Draw Lewis Structures for Simple Molecules and Ions with a Central Atom... 

It should be clear by now that risk assessors do not know how to draw a sharp line between safe and unsafe exposures to any chemical. The very notion of safety is scientifically wrongheaded, if it is to mean the absolute absence of risk. If safety is defined in this way, it... 

How to draw conformational isomers and to flip cyclohexane rings... 

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