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Organic Chemistry

Why do only covalently bonded molecules show Isomerism?

Around the early 1800s, scientists began to notice the presence of isomerism in all types of compounds; however, at the time, it was referred to using different names.

The term allotrope was used to describe different varieties of an element that existed in different physical forms, such as diamond or graphite for carbon or monoclinic or rhombic for sulfur. Polymorphism was used to explain compounds that occurred in more than one crystalline form, like aragonite and calcite, both crystalline forms of calcium carbonate.

What is Degree/Level of Unsaturation (LU) or Double Bond Equivalent (DBE)? How to find and interpret DBE values?

The DBE calculation uses the general molecular formula to find the presence of unsaturation in a compound. The unsaturation is calculated in levels or degrees. 

The lowest degree of unsaturation (DOU) indicates minimum unsaturation, where there is the least loss of hydrogens to form a pie bond or a cyclic ring, like in cycloalkanes.

 

General Molecular Formula

What is the role of atomic shape in London Dispersion? Explain with an example

London dispersion forces are the weak intermolecular attractive forces that occur when the molecules are spaced closely. If the spacing is compact, the interactions are stronger. This means that the temporary dipoles induced due to the dispersion of electrons are also larger. Such a compact cluster will require more energy to break, raising the physical properties of the melting and boiling point.