In some cultures the engagement ring will be worn on the fourth finger of the right hand. The wedding band alone, or together with the engagement ring will be worn on the fourth finger of the left hand after marriage. It is automatically known, when you see a ring on the right hand that the young lady is engaged.If she is not engaged she can wear a ring with any kind of stone on her left hand.ngagement rings are different from wedding rings primarily in that they are worn before a legal or symbolic marriage ceremony. They are often bought before the wedding rings as well, although some people choose matching sets that are purchased together.
In chemistry, stereospecificity is the property of a reaction mechanism that leads to different stereoisomeric reaction products from different stereoisomeric reactants, or which operates on only one (or a subset) of the stereoisomers.he addition of singlet carbenes to alkenes is stereospecific in that the geometry of the alkene is preserved in the product. For example, dibromocarbene and cis -2-butene yield cis -2,3-dimethyl-1,1-dibromocyclopropane, whereas the trans isomer exclusively yields the trans cyclopropane.
Stereoisomers (spatial isomers) are isomers of the same substance that only differ in the spatial arrangement of their atoms. The maximum number of stereoisomers that can exist for a compound is 2n, where n is the number of chiral centers. Chiral centers are atoms, usually C, bonded to four different groups. Stereoisomers that differ in the direction they rotate a plane of polarized light are called optically active, or chiral, and their isomers are called enantiomers. All enantiomers are stereoisomers but not all stereoisomers are enantiomers.