Two or more forms of the same element that differ in properties but exist in the same physical state are called what?

Two or more forms of the same element that exhibit different properties while existing in the same physical state are known as allotropes. This phenomenon occurs because the atoms of the same element can bond together in various ways, leading to different structural arrangements. A common example of allotropy is carbon, which has several allotropes, including diamond and graphite. Although both forms are solid at room temperature, they have vastly different physical characteristics and chemical behaviors due to their distinct atomic arrangements.

Isomers, on the other hand, are different compounds that have the same molecular formula but differ in arrangement or connectivity of atoms. Compounds consist of two or more different elements that are chemically bonded together, rather than variations of a single element. Mixtures are physical combinations of two or more substances where each retains its own properties, not involving the changes or reconfiguration of atoms. Therefore, the term that correctly describes different forms of the same element is allotropes.