Béda révisi "Beungkeut kovalén"

5 bita ditambahkeun ,  3 tahun yang lalu
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Ngarapihkeun éjahan, replaced: model → modél (5)
m (Ngarapihkeun éjahan, replaced: rea → réa (4), ea → éa (8), eo → éo using AWB)
m (Ngarapihkeun éjahan, replaced: model → modél (5))
 
[[Image:covalent.svg|right|thumb|160px|Early concepts in covalent bonding arose from this kind of image of the molecule of [[methane]]. Covalent bonding is implied in the [[dot and cross diagram]] that indicates sharing of electrons between atoms.]]
 
While the idéa of shared electron pairs provides an effective qualitative picture of covalent bonding, [[quantum mechanics]] is needed to understand the nature of these bonds and predict the structures and properties of simple molecules. [[Walter Heitler]] and [[Fritz London]] are credited with the first successful quantum mechanical explanation of a chemical bond, specifically that of [[molecular hydrogen]], in 1927. Their work was based on the valence bond modelmodél, which assumes that a chemical bond is formed when there is good overlap between the [[atomic orbitals]] of participating atoms. These atomic orbitals are known to have specific angular relationships between éach other, and thus the valence bond modelmodél can successfully predict the bond angles observed in simple molecules.
 
== Bond polarity ==
== Current theory ==
 
Today the valence bond modelmodél has been supplanted by the [[molecular orbital]] modelmodél. In this modelmodél, as atoms are brought together, the ''atomic'' orbitals interact to form ''molecular'' orbitals, which are linéar sums and differences of the atomic orbitals. These molecular orbitals are a cross between the original atomic orbitals and generally extend between the two bonding atoms.
 
Using quantum mechanics it is possible to calculate the electronic structure, energy levels, bond angles, bond distances, dipole moments, and electromagnetic spectra of simple molecules with a high degree of accuracy. Bond distances and angles can be calculated as accurately as they can be méasured (distances to a few pm and bond angles to a few degrees). For small molecules, calculations are sufficiently accurate to be useful for determining thermodynamic héats of formation and kinetic activation energy barriers.
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