Bond Chemical Delokal dan Resonance

Delokal bonding found in compounds containing unsaturated one or more bonding orbitals are not limited to the two atoms, but spread up to three atoms or more. Such a bond is called bond delokal. In the valence bond method, to describe the actual structure of Such molecules, several Lewis structures (canonical form) is written, then taken their average weight. The weight of an average of two or more forms called resonance.

Bond Energy

There are two types of binding energy. The energy required to break a bond produce the radical is called dissociation energy D. For example D for H2O → HO + H is 118 kcal / mol. However, this value is not selected as the binding energy OH in water because of D for HO → H + O is 100 kcal / mol. The average of these two values The (109 kcal / mol) was chosen as the binding energy E. For methane, the total energy change of CH4 into C + 4H (at 0 K) is 393 kcal / mol. This means E for the CH bond in methane is 98 kcal / mol at 0 K. In the molecular diatoms, of course D = E. The heat of combustion is known exactly is burning hothydrocarbons. For methane, combustion heat value at 25oC was 212.8 kcal / mol, which leads to heat atomisasinya value is 398.0 kcal / mol (At 25oC), or the value of E for CH bond is 99.5 kcal / mole at 25oC.  

Bond angle

Sp3 carbon bond angle can be expected is always equal to the tetrahedral 109o28 ', but this can only happen if the four clusters are bound are identical as in methane, neopentana, or carbon tetrachloride. Most cases are found where there has been little deviation from the angles in pure tetrahedarl. As examples of CC-Br angles in 2-bromopropana is 114.2 o. A similar found deviations from the point of 120o to 180o angle to sp2 and sp. This deviation occurs because of slight differences hybridization.

Long bond

The distance between the atoms in the molecule is characteristic of molecules and can provide valuable information when compared with the same bond in different molecules.

The primary method of determining the bond length and angle is the x-ray diffraction (for solids), electron diffraction (only for gas), and methods spektroskofi.

Induction and Field Effects

CC bond in ethane is perfect because the bond is nonpolar connecting the two atoms are equivalent. However, the C-C bond in kloroetana polarized by the presence of electronegative chlorine atoms. This polarization is actually the sum of two effects.

Covalent Molecules Ionic Character

It is known that in the bond A - B where A and B have differences in electronegativity, the bond is purely covalent. As an example we using hydrochloric acid.