Question

What do you call the compounds having the same molecular formula but different structural arrangements of atoms?

Answer 1

Hint: We know that the isomers have the same molecular formula but a difference in chain length, functional group and its position make them different from each other. In the conformational isomers, the isomerism arises only due to differences in the spatial arrangement of bonds.

Complete answer:
As we know that the molecules with the same molecular formula are different and are defined as isomers. Isomers are the molecules that have the same molecular formula but a different structure. The isomer which has the same molecular formula but the difference in connectivity of bond or functional group is called the structural isomers. The isomers in which the atoms are arranged in a completely different order with that of the molecular formulas. The atoms which have the same atomic number of each element then are said to be isomers. It is necessary that they have the same physical and chemical properties.
The arrangements of atoms in space are different. Isotones: The elements are said to be isotones if they have the same number of neutrons but have different numbers of protons. The isomers which differ in the atomic arrangement of the atoms in molecules without any kind of reference to the spatial arrangement are called the structural isomers. This is also called constitutional isomerism. These isomers have the same molecular formula but different connectivity between the atoms. Thus, such different compounds which have the same molecular formulas are called isomers. Structural isomers are compounds with the same number and type of atoms in their molecules, but have them bonded to one another in a different arrangement.

Note:
Remember that the presence of different numbers of electrons, protons and neutrons isotopes and isobars have different properties. There are both the same chemical and physical properties in isotopes whereas in isobars, they have the same physical properties only.