When is carbon positively charged

If this adds to an alkene it will also result in an anion. Maybe you want to edit your question to change that. Add a comment. Active Oldest Votes. Improve this answer. Well this is where the confusion lies. Good Luck :. Karan Singh Karan Singh 3, 8 8 gold badges 32 32 silver badges 49 49 bronze badges.

In addition, the atoms must balance. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.

Rockefeller, Andrew Carnegie, and even Bill Gates: while they may have been thought of as greedy, they also have a philanthropic side. So in these cases these atoms are not actually electron-deficient. It is extremely energetically unfavorable for atoms like F, O, and N to have less than a full octet of electrons. Here comes the second most important principle when it comes to stabilizing positive charge: if possible, it is best to place the positive charge on the most substituted carbon atom.

The stability of carbocations increases with the number of attached alkyl groups. It might be useful to review the 3 factors that stabilize carbocations. The last factor to keep in mind is essentially the inverse of what we just discussed. Carbocations are destabilized when adjacent to electron-withdrawing groups. Again, it might be useful to review the 3 factors which destabilize carbocations. So hopefully that mostly covers an introduction to evaluating the stability of different resonance forms.

Next Post: Applying Resonance 1 : Pi-donation. Think you dropped a positive charge on the structure on the left of the first example in the last figure! But otherwise, great work.

Electronegativity is a way of quantifying the amount of "pull" on the shared electrons in a covalent bond towards one atomic center, or the other. Fluorine is the most electronegative element type of atom. It is arbitrarily given a value of 4. These are the least electronegative elements the noble gasses are not usually rated. This is called the Pauling scale and is the one most commonly used for defining relationships between atoms and elements.

If it has two bonds and two lone pairs, as in water, it will have a formal charge of zero. If it has one bond and three lone pairs, as in hydroxide ion, it will have a formal charge of When we get to our discussion of free radical chemistry in chapter 17, we will see other possibilities, such as where an oxygen atom has one bond, one lone pair, and one unpaired free radical electron, giving it a formal charge of zero.

For now, however, concentrate on the three main non-radical examples, as these will account for virtually everything we see until chapter Nitrogen has two major bonding patterns, both of which fulfill the octet rule:. If a nitrogen has three bonds and a lone pair, it has a formal charge of zero. In a fairly uncommon bonding pattern, negatively charged nitrogen has two bonds and two lone pairs.

Two third row elements are commonly found in biological organic molecules: sulfur and phosphorus. Remember that elements in the third row of the periodic table have d orbitals in their valence shell as well as s and p orbitals, and thus are not bound by the octet rule. Finally, the halogens fluorine, chlorine, bromine, and iodine are very important in laboratory and medicinal organic chemistry, but less common in naturally occurring organic molecules.

Halogens in organic compounds usually are seen with one bond, three lone pairs, and a formal charge of zero. Once you have gotten the hang of drawing Lewis structures, it is not always necessary to draw lone pairs on heteroatoms, as you can assume that the proper number of electrons are present around each atom to match the indicated formal charge or lack thereof.

Occasionally, though, lone pairs are drawn if doing so helps to make an explanation more clear. As an example of how formal charges can be used to determine the most stable Lewis structure for a substance, we can compare two possible structures for CO 2. Both structures conform to the rules for Lewis electron structures. C is less electronegative than O, so it is the central atom.

C has 4 valence electrons and each O has 6 valence electrons, for a total of 16 valence electrons. Dividing the remaining electrons between the O atoms gives three lone pairs on each atom:. This structure has an octet of electrons around each O atom but only 4 electrons around the C atom. No electrons are left for the central atom. To give the carbon atom an octet of electrons, we can convert two of the lone pairs on the oxygen atoms to bonding electron pairs.

There are, however, two ways to do this. We can either take one electron pair from each oxygen to form a symmetrical structure or take both electron pairs from a single oxygen atom to give an asymmetrical structure:. Both Lewis electron structures give all three atoms an octet.