Is a structural isomer same formula different arrangement?

structural isomers: two substances having the same molecular formula but different physical and chemical properties because the arrangement of their component atoms is different.

Structural isomers, also called constitutional isomers, have the same molecular formula but different arrangements of atoms. We will typically refer to them as having a different bond pattern.

Be careful not to draw "false" isomers which are just twisted versions of the original molecule. For example, this structure is just the straight chain version of butane rotated about the central carbon-carbon bond.

Structural Isomers are molecules which have the same molecular formula but have different connectivities (The Order They Are Put Together).

In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a compound is a compound that contains the same number and type of atoms, but with a different connectivity (i.e. arrangement of bonds) between them. The term metamer was formerly used for the same concept. For example, butanol H3C−(CH2)3−OH, methyl propyl ether H3C−(CH2)2−O−CH3, and diethyl ether (H3CCH2−)2O have the same molecular formula ...

Consider the molecular formula \(C_7H_7Cl\). There are four different isomers you could make depending on the position of the chlorine atom. In one case it is attached to the side-group carbon atom, and then there are three other possible positions it could have around the ring - next to the \(CH_3\) group, next-but-one to the \(CH_3\) group, or opposite the \(CH_3\) group. In this variety of structural isomerism, the isomers contain different functional groups - that is, they belong to different families of compounds (different homologous series).

Figure \(\PageIndex{2}\): Conformational isomers of pentane. A structural isomer, also known as a constitutional isomer, is one in which two or more organic compounds have the same molecular formulas but different structures.

Isomers are molecules with the same molecular formulas, but different arrangements of atoms. We will look at some isomer possibilities for alkanes and alkenes. A structural isomer is one in which two or more or organic compounds have the same molecular formulas but different structures.

For example, trans-2-butene and cis-2-butene differ in their conformation, but the bonds between atoms do not change from one molecule to the next. This means that while they look different, they are stereoisomers, and not structural isomers.