The convention of drawing two or more resonance contributors to approximate a single structure may seem a bit clumsy to you at this point, but as you gain experience you will see that the practice is actually very useful when discussing the manner in which many functional groups react. As our example, we will use formate, the simplest possible carboxylate-containing molecule. The conjugate acid of formate is formic acid, which causes the painful sting you felt if you have ever been bitten by an ant.
Usually, you will see carboxylate groups drawn with one carbon-oxygen double bond and one carbon-oxygen single bond, with a negative formal charge located on the single-bonded oxygen. In actuality, however, the two carbon-oxygen bonds are the same length, and although there is indeed an overall negative formal charge on the group, it is shared equally between the two oxygens. Therefore, the carboxylate can be more accurately depicted by a pair of resonance contributors.
Both carbon-oxygen sbonds, then, are formed from the overlap of carbon sp 2 orbitals and oxygen sp 2 orbitals. In addition, the carbon and both oxygens each have an unhybridized 2 p z orbital situated perpendicular to the plane of the sigma bonds.
Formic acid is a colorless liquid with a pungent and penetrating odor. It is highly soluble in water and polar solvents. It exists as a hydrogen-bonded dimer in the vapor phase as well as in hydrocarbons.
Here, we will discuss the chemical bonding in the formic acid by drawing its Lewis structure, understanding its molecular geometry, and hybridization. Then, we will move towards the polar nature of formic acid.
The Lewis structures or electron dot structures are the two-dimensional diagrams, which represent the bonding electron pairs between atoms of the molecule and lone pairs of electrons on an atom if present. The bonding and nonbonding electrons are valence electrons, which are present in the outermost shell of an atom.
As per the Lewis rule or octet rule, an atom tends to bond with other atoms in such a way that every atom has eight electrons in its valance shell except hydrogen and helium. Step 1 : Count the total number of valence electrons in the molecule by writing down the electronic configuration of the atom. The electronic configuration of carbon, hydrogen, and oxygen atom is [He] 2s22p2, 1s1, and [He] 2s22p4, respectively.
Therefore, the valence electrons in C, H, and O are 4, 1, and 6, respectively. There are two hydrogen atoms and two oxygen atoms in formic acid. Step 2 : The least electronegative atom with the maximum number of group valence acts as a central atom. Group valence is the maximum number of bonds an atom can form with other atoms. The group valance of C, H, and O is 4, 1, and 2, respectively. Hence, the carbon atom will act as a central atom. In the skeletal structure of formic acid, the carbon atom will be surrounded by H, O, and OH groups.
Step 3 : Arrange all the valence electrons in the skeletal structure of the molecule. We have 18 valence electrons, which need to be arranged in the Lewis structure of the formic acid. First of all, start with the carbon atom as it is a central atom. The carbon atom will be surrounded by eight electrons as per the octet rule. It will complete the duplet of hydrogen, which is attached directly to the carbon atom. Now, the oxygen atom attached to the carbon atom will share four electrons or two bond pairs of the electron with the carbon atom.
It will also have two lone pairs of electrons four electrons to complete its octet. The remaining six electrons will be distributed in the OH group bonded to the carbon atom. Therefore, the possible Lewis structure of formic acid would be:. The two bonding electrons will form a single bond and four bonding electrons will form a double bond. Hence, the Lewis structure of formic acid can be drawn as:. The Lewis structure is a simple representation of the molecule.
It does not give any information about the shape of the molecule and the hybridization of the atom in the molecule. It considers the repulsions between bonding and nonbonding lone pair valence shell electrons.
This allows methylation to have long-term effects, and is one of the principles of epigenetic regulation and inheritance. Carbon A is hybridized because this carbon is only bonded to two other atoms. Carbon B is bonded to four atoms, and would therefore be hybridized.
Keep in mind that a carbon involved in a triple bond will always be hybridized, a carbon involved in a double bond will be hybridized, and a carbon involved only in single bonds will be hybridized. If you've found an issue with this question, please let us know. With the help of the community we can continue to improve our educational resources. If Varsity Tutors takes action in response to an Infringement Notice, it will make a good faith attempt to contact the party that made such content available by means of the most recent email address, if any, provided by such party to Varsity Tutors.
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Which organelle would have the most negative effect if its membrane were damaged? Possible Answers: Mitochondria. Correct answer: Lysosomes. Explanation : The lysosomes contain an acidic environment and digestive enzymes. Report an Error.
What is the predicted molecular orbital hybridization state of the carbon in carbonic acid? Possible Answers: sp. Correct answer: sp 2. Explanation : Carbons bound via one double bond are sp 2 hybridized, as long as the remaining two bonds are each sigma bonds. When formic acid is completely reduced, methanol is formed. What is the hybridization of the carbon in formic acid, compared to the carbon in methanol?
Possible Answers: The carboxylic acid has sp 2 hybridization and the alcohol has sp 3 hybridization. Correct answer: The carboxylic acid has sp 2 hybridization and the alcohol has sp 3 hybridization. Explanation : In order to find the hybridization of an atom, simply count the number of sigma bonds and lone pair electrons around the atom. Possible Answers: Tertiary radical carbons are the least stable. Radical reactions always terminate by binding to the wall of the reaction container.
Correct answer: Radical carbons are sp 2 hybridized. Explanation : Radical reactions have an sp 2 , trigonal planer carbon radical intermediate. Example Question : Mcat Biological Sciences. Possible Answers:. Correct answer:. Explanation : 2-butyne has the following chemical structure. What carbon hybridizations can be found in one molecule of acetic acid?
Possible Answers: and. Correct answer: and. Explanation : Acetic acid has the formula. Which of the following statements about the character of a bond is true? Possible Answers: The more "s" character a bond has, the more stable it is. The more "s" character a bond has, the weaker it becomes. The more "s" character a bond has, the higher the energy in the bond.
The more "s" character a bond has, the longer the bond becomes. Correct answer: The more "s" character a bond has, the more stable it is.
Explanation : The character of a hybrid orbital is defined as the extent to which it resembles the unhybridized orbitals that created it. Possible Answers: A and C. Correct answer: A and C. Explanation : The answer is arrows A and C. The methyl group forms hydrogen bonds with DNA.
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