When forming a chemical kemflo international bond between two or more atoms there may be a transfer

"The electronegativity kemflo international of TEACHING SCIENCE MATTER and science
When forming a chemical kemflo international bond between two or more atoms there may be a transfer of electrons from one of them to another, or a sharing of electrons. When one or more electron kemflo international pairs are shared, the latter generally move in a region of space between the nuclei kemflo international of the corresponding atoms. In some cases evenly kemflo international distribute their time between the two nuclei, keeping also equidistant between them. This is the case of bonding electrons of diatomic molecules (H 2, O 2, Cl 2, Br 2, N 2, F 2, I 2,): these are molecules for which one can push through a plane of symmetry between the two nuclei. It speaks of pure covalent bond, typical of the union of two identical atoms. In other cases, the electron pairs are not strictly shared between the two atoms but are moved so little kemflo international or very pronounced towards one of the two atom. This happens when the two atoms are different and each is a different tendency to attract electrons. The shared electrons spend most of their time near the nucleus of the atom "more attractive". The result is a molecule kemflo international that does not have a plane of symmetry kemflo international between the two cores. We talk about polar covalent kemflo international bond. The greater the difference kemflo international of attraction, will be the more polar bond. But there is a limit. When crossing, the difference in attraction to the electrons shared between two atoms becomes such that an atom gives the electron and the other buys it, you have the ionic bond.
This tendency to attract more or less strongly the electrons during a chemical bond has been defined electronegativity. The most common kemflo international way to represent the electronegativity is the scale of Linus Carl Pauling (1901-1994), which is based on the dissociation energies of binding. Considering only the most electronegative elements, you have the following values: Fluorine 4.0, oxygen 3.5, nitrogen kemflo international 3.0, 3.0 chlorine, bromine 2.8, sulfur 2.5, 2.5 carbon, iodine 2 , 4. Note their positions on the periodic table. Among the less electronegative elements instead: Cesium 0.7, 0.8 rubidium, potassium 0.8, 0.9 barium,

sodium 0.9, 1.0 strontium, calcium 1.0, 1.0 lithium. In this case we note that they are on the opposite side of the board with respect to those more electronegative, are alkali metal or alkaline-earth metals. Looking at the first picture you have an overview of the electronegativity.
But the electronegativity can also be expressed in the scale of Robert Sanderson Mulliken (1896-1986) in which is calculated with the formula E = (I + A) / 2, where I and A are respectively the ionization potential and the affinity electronic element. Is nothing kemflo international more than the arithmetic mean of the ionization potential and electron affinity.
In general,

when the difference in electronegativity between the two atoms of the bond is zero or close to zero, we will have a covalent bond pure. If this difference is greater than the value of 1.7 to 1.8 and therefore are markedly different, the bond will be ionic, kemflo international in intermediate kemflo international cases the bond is polar covalent. In molecules with polar bond, the barycentre of the positive

charges does not coincide with that of the negative charges

and the molecule itself behaves like an electric kemflo international dipole, ie it contains zones of opposite kemflo international charge indicated with the symbols + and d -.
The first image shows how to change the value dell'elettronegatività the periodic table. The other indicates that the ionic bond and the covalent pure are two extreme cases and in the middle are the polar covalent kemflo international bonds.
"The dangers

of the chemical table Aspartame sweetener issue 'Actions Comments (RSS) Trackback Information Date: April 27, 2012 Tags: electronegativity, chemical bonding, Mulliken, Pauling Categories: Miscellaneous Topics Leave a comment
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