The electronic structure of the atom, Lewis structures, types of bonding, electronegativity, and formal charges are some of the concepts that are essential for success in organic chemistry.
Predict patterns of bonding involving C, H, O, N, and the halogens.
Evaluate the relative importance of resonance forms and identify resonance-stabilized structures.
Condensed structural formulas and line-angle formulas are commonly used in organic chemistry.
Predict the geometry of organic molecule based on their bonding.
Explain the differences between isomers.
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A whole branch of chemistry is devoted to emitting the yellow light that fireflies use to attract mates and prey.
Chains and rings of carbon atoms can be used to build many different types of molecule.
The basis for life on Earth is the diversity of carbon compounds.
Complex organic compounds serve a variety of functions in living creatures.
The study of compounds from living organisms and their natural products was the original focus of the science of organic chemistry.
The study of compounds with the vital force was the subject of organic chemistry.
The study of gases, rocks, and minerals was the subject of inorganic chemistry.
In the absence of oxygen, chemists synthesise heating it.
The vital force of urea was presumed to come from living organisms, but it is not.
Some chemists claimed that a trace of vital force from Wohler's hands could have contaminated the reaction, but most recognized the possibility of synthesizing organic compounds.
The vital force theory was discarded after many other syntheses were carried out.
You would think vitalism would be extinct by now, because it was disproved in the early 19th century.
Vitalism is alive and well in the minds of those who believe that vitamins, flavor compounds, and similar compounds are different and more healthful than the identical "artificial" compounds.
The plant-derived compounds and the synthesized com pounds are the same.
If they are pure, the only way to tell them apart is through 14C dating, which shows the decay of 14C in compounds made from petrochemicals.
Plants have recently been synthesised from CO2 in the air.
They have more radioactive 14C.
Some large chemical suppliers show their "naturals" have high 14C content and are plant-derived.
This form of vitalism has a high-tech flavor.
Even though organic compounds do not need a vital force, they are still degraded from other compounds.
Most of the carbon compounds are classified as organic.
The organic compounds in our food nourish us.
All of the organic compounds in our bodies are found in our cells.
Our bodies are protected by complex organic compounds.
Many of the complex molecules have been synthesised by chemists.
Synthetic products include drugs, medicines, plastics, pesticides, paints, and fibers.
Advances in organic chemistry are some of the most important advances in medicine.
Synthetic drugs are used to fight disease and new materials are used to replace failing organs.
It has gone full circle.
The AbioCor self-contained artificial materials we need to save or replace those organs were derived from compounds derived from "organs."
The valves and inner bladder are made of polyurethane and are part of the outer shell.
We need to review some basic principles before we start studying organic chemistry.
Understanding the structure and bonding of organic compounds is dependent on the concepts of atomic and molecular structure.
The atoms are composed of protons, neutrons, and electrons.
There are positively charged and un charged particles in the nucleus.
The space surrounding the nucleus is occupied by electrons, which have a negative charge that is 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- Nuclear particles have the same mass as an electron.
The nucleus contains most of the cloud of electrons that make up the atom.
The number of neutrons is similar to the number of protons.
The nucleus of the most common kind of carbon atom has six protons and six neutrons.
The mass number of carbon atoms is 13, written 13C.
The basic atomic structure of the 14C is radioac.
The time it takes for half of the nucleus to decay is known as the half-life.
A dense, positively charged nucleus predictable decay of 14C is used to determine the age of organic materials up to about surrounded by a cloud of electrons.
The chemical properties of an element are determined by the number of protons and electrons in the nucleus.
The structure of the resulting molecule is determined by the electrons forming bonds.
Because they are small and light, electrons show properties of both particles and waves; in many ways, the electrons in atoms and molecules behave more like waves than like particles.
Most of the elements in organic compounds are found in the first two rows of the periodic table, indicating that their electrons are in the first two electron shells.
The distance from the nucleus affects the electron density.
The nodal plane is a flat region of space with no electron density.
In order to get the proper treatment for the psychiatric disorder known as number of electrons, we need to start with a mood-stabilizing agent.
The table shows the ground-state electronic configurations.
There are elements in the first two rows of the table.
There are two more concepts illustrated in the table.
Nitrogen and carbon have an inability to sleep.
Oxygen has six and we don't.
Helium has a first shell with two electrons and a second shell with eight electrons.
The first column of the periodic table has hydrogen and lithium in it.
Carbon is in the group 4A of the periodic table.
Carbon's third and fourth electrons are separate from each other.
The Pauli exclusion principle does not mean that two electrons can occupy the same orbital.
When we talk about forming a molecule.
The electron configuration elements have octets.
There are two ways that atoms can interact.
Sometimes electrons are transferred from one atom to another.
The neon configuration has one electron less than the fluorine configuration.
A noble-gas configu ration is given to these two elements by a single electron transfer.
The formation of a large crystal lattice is the result of ion bonding.
Ionic bonding is rare in organic compounds.
A second electron is needed to achieve the noble-gas configuration of hydrogen.
If two hydrogen atoms come together and form a bond, they share their two electrons, and each atom has two electrons in its valence shell.
We will look at bonding in more detail later in the chapter.
Each electron is represented by a dot.
We try to arrange the atoms so that they have their noble-gas configurations: two electrons for hydrogen and octets for the second-row elements.
Take a look at the Lewis structure of methane.
Each hydrogen contributes one to give a total of eight electrons.
Each hydrogen atom shares two of the electrons with the carbon atom, and all eight electrons surround carbon to give it an octet.
We have distributed the total number of valence electrons so that each carbon atom is surrounded by 8 and hydrogen.
The only possible structure for ethane is shown, with the two carbon atoms sharing a pair of electrons and each hydrogen atom sharing a pair with one of the carbons.
The ability to form strong carbon-carbon bonds is shown by the ethane structure.
Oxygen atoms, nitrogen atoms, and the halogens have nonbonding electrons in their stable compounds.
The lone pairs of nonbonding electrons serve as reactive sites in their parent compounds.
Two lone pairs of electrons on the nitrogen atom of methylamine are shown in the Lewis structures.
The structure of chloromethane shows three lone pairs of halogen atoms.
Any lone pairs should be shown in a correct Lewis structure.
Most or all of the lone pairs are not included in the structures drawn by organic chemists.
The correct number of nonbonding electrons is what Lewis structures are not.
Lewis structures are the way we draw structures.
We placed just one pair of electrons between the two atoms in the Lewis structures.
Many molecules share two or three electron pairs.
A double bond is found in ethylene (C2H4).
The only way to show both carbon atoms with octets is to draw them sharing two pairs of electrons in a Lewis structure.
There are examples of organic compounds with double bonds.
Two atoms share four electrons to give them octets.
A double dash is a sign of a double bond.
Acetylene has a triple bond.
The Lewis structure shows three pairs of elec trons between the carbon atoms.
There are examples of organic compounds with triple bonds.
A triple dash is a sign of a triple bond.
At high pressures, H hydrocarbon is very dangerous.
Oxygen is usually used in welding and two bonds of nitrogen are formed.
Only one bond is formed between hydrogen and the halogens.
Nitrogen is trivalent even underwater.
Oxygen is divalent in gas cylinders.
By remembering that acetylene is dissolved in acetone to the usual number of bonds for common elements, we can keep it from getting too concentrated.
If we draw a structure with each atom having its usual number of bonds.
Lewis structures for the following formulas are "usual numbers of bonds".
Three bonds to nitrogen might be three single bonds, one single bond and one double bond, or one triple bond.
Circle any pairs of nonbonding electrons in the structures you drew.
Nonpolar cova lent bonds are the C bond in ethane.
The bonding electrons are attracted to one of the two nuclei in most bonds.
The bonding electrons are attracted to the chlorine atom more strongly when carbon is bonding to it.
The chlorine atom has a partial negative charge and the carbon atom has a partial positive charge.
A crossed arrow pointing from the + charge toward the - charge is used to symbolize a dipole moment.
The red area has electron-rich regions.
The red region shows a partial negative charge on chlorine, while the blue region shows a partial positive charge on carbon and the hydrogen atoms.
The Pauling electronegativity scale is used by organic chemists and is useful for predicting the polarity of bonds.
The bonding electrons are attracted to elements with higher electronegativities.
The negative end of the dipole is the atom with the higher electronegativity.
The electronegativities increase from left to right.
Nitrogen, oxygen, and the halogens are more negative than positive.
H bonds are nonpolar.
In Section 2-1, we will look at the bonds and molecule's polarity.
There is a partial negative charge on chlorine and a partial positive charge on carbon in Chloromethane.
The colors show values of potential.
The direction of the dipole moments of the bonds can be predicted using electronegativities.
If the Lewis structure shows that an atom has a formal charge, it bears at least part of it.
The concept of formal charge helps us determine which atoms have the most charge in a charged molecule, and it also helps us to see charged atoms in molecules that are neutral overall.
To calculate formal charges, count how many electrons contribute to the charge of each atom and compare that number with the number of valence electrons in the free, neutral atom.
Each hydrogen atom in methane has a bonding pair of electrons.
One electron is what hydrogen needs to be neutral.
Hydrogen atoms with one bond are neutral.
There are four bonding pairs of electrons in the carbon atom.
Four electrons are what carbon needs to be neutral, and half of the electrons are four electrons.
Carbon is neutral when it has four bonds.
The ion has a positive charge and we use eight electrons from oxygen and hydrogens to make the Lewis structure.
Each hydrogen has a single bond.
Oxygen has six bonding electrons and two nonbonding electrons.
Oxygen needs six valence electrons to be neutral because half the bonding electrons plus all the nonbonding electrons contribute to its charge.
The oxygen atom has a formal charge of +2.
The individual atoms are formally charged in this neutral compound.
Nitrogen and Boron have four bonding pairs of electrons according to the Lewis structure.
The charges of both nitrogen and boron are contributed by 4 electrons.
Nitrogen needs five electrons to be neutral, so it has a formal charge of +2.
Boron has a formal charge of -1 because it only needs three electrons to be neutral.
There are four pairs of bonding electrons in this structure.
With four bonds, carbon is neutral, but nitrogen is in group 5A and has a positive charge.
The carbon atom has three bonds and six bonding electrons.
Carbon is one short of the four needed to be neutral, FC is 4 - 0 - 12(6).
Nitrogen has bonding and nonbonding electrons.
Section 1-9 discusses the significance of the two Lewis structures.
This table is very important.
You can recognize patterns that are unusual or wrong.
Most organic compounds have a few common elements.
The table shows the most common bonding structures using dashes.
The charges shown on these structures can be verified using the rules for calculating formal charges.
A good understanding of the structures shown here will help you draw organic compounds quickly and correctly.
Some organic compounds have ionic bonds.
The structure of CH3NH3Cl cannot be drawn with just covalent bonds.
It would require nitrogen to have five bonds.
The correct structure shows the bond between the ion and the rest of the structure.
Molecules can be drawn either ionically or covalently.
It is possible to draw NaOCOCH3 with either a covalent bond or an ionic bond.
The ionically bonded structure is preferred because it forms ionic bonds with oxygen.
The bonds between atoms with large electronegativity differences are usually drawn as ionic.
Draw Lewis structures for the compounds and ion.
The molecule will usually show the characteristics of both structures if two or more structures are possible.
The structure of this ion is a resonance hybrid.
The positive charge is on carbon, but it does not have an octet.
We can imagine moving nitrogen's nonbonding electrons into the bond to give the second structure, with a positive charge on nitrogen and an octet on carbon.
The representation attempts to combine the two forms into a single picture.
If the charge were only on the carbon or nitrogen, the ion wouldn't be stable.
When a charge can be delocalized over two or more atoms, resonance is most important.
The chemistry of compounds with double bonds is dependent on resonance stabilization.
The acidity of acetic acid is enhanced by resonance effects.
A negative charge is created over both of the oxygen atoms when acetic acid loses a protons.
The oxygen atom bears half of the negative charge.
An equilibrium is represented by two arrows in opposite Second-row elements.
Sometimes we use curved arrows to help us see O, F, but we can't have more than eight how we mentally move the electrons between one resonance form and another.
All the resonance forms are delocalized at the same time.
Some un charged molecules have structures with equal positive and negative charges.
Remember that individual resonance forms do not exist.
The molecule doesn't convert reactants to products.
There are some characteristics of both.
A mule is a hybrid of a horse and donkey.
The mule does not equal rates of the forward and "resonate" between looking like a horse and looking like a donkey; it looks like a mule reverse reactions.
We can estimate the relative energies of green curved arrows if they existed.
More stable resonance forms a more accurate representation of the molecule than less stable ones.
The two resonance moving electrons from one form have the same bonding as the one shown in the earlier 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846 888-666-1846
The two forms of nitromethane are the same.
The resonance forms are different.
The structures are not equal.
The first structure has a charge on nitrogen.
The carbon atom does not have an octet, but the second has a positive charge on carbon.
The first structure is more stable because it has an additional bond.
Stable ion have a positive charge on a nitrogen atom with four bonds.
The lower-energy forms are more stable than the higher-energy ones.
Major and minor resonance contributors are found in many organic molecules.
Formaldehyde can be written with a negative charge on oxygen and a positive charge on carbon.
There is a positively charged carbon atom.
The charge-separated structure helps explain why the O bond is very polar, with a partial positive charge on carbon and a partial negative charge on oxygen.
The map shows an electronrich region around oxygen and an electron-poor region around carbon.
We try to draw structures that are low in energy.
The best candidates have the maximum number of bonds and the maximum number of octets.
The minimum amount of charge separation is something we look for.
nuclei can't be delocalized.
They have the same bond distances and angles in all of the resonance contributors.
The Lewis structures for the compound must be valid.
Second-row elements can't have more than eight electrons in their valence shells.
The placement of the electrons is the only thing that can be shifted.
Double bonds and nonbonding electrons are shifted the most.
All bond angles must remain the same.
resonance is rarely involved in sigma bonds.
The one with the lowest energy is the major resonance contributor.
If the atoms have octets, they can bear a positive charge.
When it serves to delocalize a charge, resonance stabilization is most important.
Draw the important resonance forms for each compound.
If the structure has the same energy, indicate which structures are major and minor contributors.
The first structure has a carbon atom with six electrons.
The second structure has an additional bond and octets.
Both of these structures have the same number of bonds.
The first structure has a negative charge on carbon while the second has a positive charge on oxygen.
The second structure is the major contributor because Oxygen is the more negative element.
SF6 is a stable compound with 12 electrons.
The last structure, with octets on all atoms, may be the major resonance contributor.
The first un charged structure is preferred by organic chemists, whereas the fourth structure with octets is preferred by inorganic chemists.
Draw the important resonance forms for each compound.
The first two forms have the same number of bonds.
The central nitrogen atom has a positive charge and the outer carbon and nitrogen have a negative charge.
The structure showing the minus charge on nitrogen is expected to be the major contributor.
The third structure is not a structure we would normally draw.
The nitrogen atom has less bonds than the other two structures.
Nitrogen has four bonds and an octet, but it rarely has a positive charge without one.
Spreading the charge over two or more atoms in a structure shows how delocalization stabilizing a cation or anion.
To explain the characteristics of a compound.
If you want to see how a cation or an anion is delocalized, you should look for double bonds and nonbonding electron pairs next to the charged atom.
A double bond next to a charged atom can delocalize the charge.
In drawing resonance forms, you can use curved arrows to keep track of the electrons as you mentally move them from one place to another.
This movement is not real.
The molecule is made up of all the resonance forms.
The charges and electrons do not move back and forth.
The resonance form will be stable if the double bond allows an element to share a negative charge.
Double bonds to oxygen and nitrogen are the most common examples.