Chemical elements that behave sometimes like metals and sometimes like nonmetals are often called ___.

Chemical elements that exhibit properties of both metals and nonmetals are known as metalloids. These elements typically have intermediate characteristics, which allows them to sometimes conduct electricity like metals, yet also display nonmetallic behavior in different contexts.

For example, metalloids can form covalent bonds, similar to nonmetals, and can also exhibit a shiny appearance like metals. This dual nature is important in various applications, particularly in the semiconductor industry where materials must conduct electricity under certain conditions while acting as insulators under others.

The other terms mentioned do not accurately describe elements with mixed properties. Nonmetals are distinct from metals and do not exhibit the same range of conductivity. Alloys refer to mixtures of metals and not to elements themselves. Compounds are substances formed from the chemical combination of two or more different elements, which does not pertain to the behavior of individual elements. Thus, metalloids are the most fitting term for elements that bridge the gap between metals and nonmetals.