Isomers

The two or more nuclides with the same number of protons and the same number of neutrons but are different in energy and manner of radioactive decay, which exists for a measurable interval of time, are known as isomers. The half-life of the most energetic isomer can be as short as about 10-11 seconds, but in some extreme cases, it can be many several years. 

Reactions formed from the bombardment of nuclei by subatomic particles or as intermediate decay products of radioactive nuclei, their direct result leads to the formation of nuclear isomers. However, the nuclei which are unstable and decay as soon as they are formed in nuclear reactions, the intermediate products which have a half-life of less than 10-11 seconds, are not generally classified as nuclear isomers.

What are geometric isomers? 

Geometric isomers are also known as Cis-Trans Isomers. Isomers are chemical species with the same chemical formulas. Still, they are also different from one another, whereas geometric isomers are chemical species that have the same type and quantity of atoms as one another. 

In geometric isomers, the atoms or groups exhibit different spatial arrangements on either side of a ring structure or a chemical bond. The geometric isomerism is also known as cis-trans isomerism or configurational isomerism.

They describe the spatial arrangement of atoms within the molecules that have the same chemical formulas. They either contain double bonds or ring structures which prevent the functional groups from freely rotating around a chemical bond. The functional groups are always on the same side of a chemical bond and are located on opposite or transverse sides of a bond.

What are cis and trans geometric isomers?

Cis is a Latin word that means on this side, and trans is also a Latin word that means on the other side. So, when the substituents are oriented in the same direction as each other, basically on the same side, the diastereomer is called cis. When the substituents are on opposing sides, then the orientation is trans.

They exhibit different properties, which include boiling points, reactivities, melting points, densities and solubilities. These differences contribute to the effect of the overall dipole moment. As a result, they cancel each other out while dipoles of cis are addictive. For example, in alkenes, trans have higher melting points and lower solubility with greater symmetry than cis isomers.

How to identify geometric isomers?

The skeletal structures with the crossed line for bonds help us to indicate geometric isomers. Still, the International Union of Pure and Applied Chemistry (IUPAC) prefers wavy lines connecting a double bond to a heteroatom. 

Examples of geometric isomers

Pt(NH3)2Cl2, two geometric isomers exist, one in which the species are arranged around the Pt in the order Cl, Cl, NH3, NH3 and another in which the species are ordered NH3, Cl, NH3, Cl.

What is isomerism?

The presence of molecules with the same number of atoms of the same type (and therefore of the same formula) but different chemical and physical properties. The etymology of “isomer” is Greek-isos and meros or “equal part”. Colloquially, isomers are compounds composed of equal parts but not the same. As a rough analogy, two bracelets, each consisting of five red and five green beads, can be arranged in different isomers depending on the colour order. Each bracelet has the same parts (5 red and 5 green beads), but each variation is different. You can even imagine the same combination of beads. The pendant chain is attached to the bracelet in various ways. You might imagine two bracelets with the same chain mounted in different directions, in the same red-green order. Such a structure is also similar to the isomer. In a more subtle analogy, the hand can be considered an isomer. All hands have the same kind of fingers, but the right hand is not completely placed on the left hand. They are different.

Conclusion: 

Isomerization is a phenomenon in which two or more compounds with similar chemical formulas but different structures exist. Compounds that exhibit this phenomenon are known as isomers. Although they have the same formula, they have different atomic arrangements and properties. The differences are due to their different spatial or structural arrangement. Basically, there are two types of isomers, structural isomers and stereoisomers.