Heteroatoms Atoms other than carbon hydrogen

While chemical bonds are represented by lines connecting atoms, electron dot notation is commonly used to represent lone pairs (nonbonding pairs) of electrons. Lone pairs are found on heteroatoms (atoms other than carbon or hydrogen) that do not require bonds with additional atoms to fill their valence shell of eight electrons. For example, atomic... 

Heteroatoms— atoms other than carbon or hydrogen. Common heteroatoms are nitrogen, oxygen, sulfur, phosphorus, and the halogens. 

All heteroatoms (atoms other than carbon and hydrogen) must be drawn, and any hydrogen atoms attached to a heteroatom must also be drawn. For example ... 

Major unknowns in the mechanism by which a hydrocarbon fuel bums concern the pyrosynthesis reactions that lead to the formation of polycyclic aromatic hydrocarbons (PAHs) and soot and the oxidation chemistry of atoms other than carbon and hydrogen (heteroatoms) in the fuel, particularly nitrogen, sulfur, and halogens. 

Hess s law phys chem The law that the evolved or absorbed heat in a chemical reaction is the same whether the reaction takes one step or several steps. Also known as the law of constant heat summation. hes-oz, 16 hetero- chem Prefix meaning different for example, a heterocyclic compound is one in which the ring is made of more than one kind of atom. hed-o-ro heteroatom org chem in an organic compound, any atom other than carbon or hydrogen. hed-3-ro,ad-3m ... 

Cleavage (the breaking of a bond) next to a heteroatom (any atom other than carbon or hydrogen) is also relatively common. This is pcirticularly important if fragmentation involves the loss of a very stable molecule such as H2O or CO2 since this would indicate the presences of very pcirticular functional groups and thus would give clues to the structure of the molecule. 

Heteroatom Any atom other than carbon or hydrogen in an organic molecule. 

Atoms other than carbon and hydrogen that appear in organic compounds are called heteroatoms. Cyclic organic compounds that contain one or more heteroatoms are called heterocycles. Heterocyclic compounds are the largest class of organic compounds and can be either aromatic (such as pyridine, pyrrole, and furan) or nonaromatic (such as piperidine, pyrrolidine, and tetrahydrofuran). 

Theoreticians call any non-hydrogen atom a heavy atom, and any heavy atom other than carbon a heteroatom. In the Hiickel model, all carbon atoms are assumed to be the same. Consequently, their Coulomb and resonance integrals never change from a and If respectively. However, heteroatom X and carbon have different electronegativities, so we have to set ccx = a. Equally, the C-X and C-C bond strengths are different, so that Pcx X p. Thus, for heteroatoms, we employ the modified parameters... 

The key to chemical reactions, including terran biochemical reactions, at standard temperatures and pressures is the reactivity of carbon-carbon and carbon-hydrogen bonds in molecules that also contain carbon-heteroatom (any atom other than carbon or hydrogen) bonds. Bonds to heteroatoms are often said to activate carbon-carbon and carbon-hydrogen bonds. In terran metabolism, the most important heteroatoms are oxygen and nitrogen, although sulfur is also important, and other heteroatoms such as phosphorus occasionally play a role. 

Heteroatoms (hetero, different ) are any atoms other than carbon and hydrogen. The rule for calculating elements of unsaturation in hydrocarbons can be extended to include heteroatoms. Let s consider how the addition of a heteroatom affects the number of hydrogen atoms in the formula. 

The term "heteroatom" applies to any atom other than carbon or hydrogen. It is common for heteroatoms to appear in locations that are inconvenient to name following basic rules, so a simple system called "replacement nomenclature" has been devised. The fundamental principle is to name a compound as if it contained only carbons in the skeleton, plus any functional groups or substituents, and then indicate which carbons are "replaced" by heteroatoms. The prefixes used to indicate these substitions are listed here in decreasing priority and listed in this order in the name ... 

From an organic chemist s viewpoint, heteroatoms are atoms other than carbon or hydrogen that may be present in organic compounds. The most common heteroatoms are oxygen, nitrogen, and sulfur. In heterocychc compounds, one or more of these heteroatoms replaces carbon in a ring. 

When certain atoms are collected into discrete units, they have special physical and/or chemical properties. Such units are known as functional groups. The C=C unit of alkenes and the C=C unit of alkynes are examples of hydrocarbon functional groups. The C-C unit of an alkane is not considered to be a functional group because it is the backbone of virtually all organic molecules. Functional groups can include atoms other than carbon or hydrogen and the presence of these other atoms (call them heteroatoms) leads to new functional groups. 

If a carbon atom is bonded to something other than hydrogen and oxygen, determination of its oxidation state becomes more challenging. StiU, it can typically be done by inspection. The term heteroatom is used to describe any atom other than carbon or hydrogen those commonly encountered in organic molecules include O, N, S, Cl, Br, and I. Since each of these atoms is more electronegative than carbon, they all have the same effect on the oxidation state of a carbon to which they are attached. 

For which compounds containing a heteroatom (an atom other than carbon or hydrogen) does the molecular ion have an even-numbered mass For which does it have an odd-numbered mass ... 

HETCOR spectrum a 2-D NMR spectrum that shows coupling between protons and the carbons to which they are attached, heteroatom an atom other than carbon or hydrogen. 

HETCOR (Section 13 19) A 2D NMR technique that correlates the H chemical shift of a proton to the chemical shift of the carbon to which it is attached HETCOR stands for heteronuclear chemical shift correlation Heteroatom (Section 1 7) An atom in an organic molecule that IS neither carbon nor hydrogen Heterocyclic compound (Section 3 15) Cyclic compound in which one or more of the atoms in the nng are elements other than carbon Heterocyclic compounds may or may not be aromatic... 

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