Polokovy

Polokovy, or metalloids, are a class of chemical elements with properties intermediate between metals and nonmetals. They often display mixed electrical conductivity, acting as semiconductors, and occupy a diagonal region on the periodic table between metals and nonmetals. Their behavior can vary with temperature and chemical environment, making them useful in a range of specialized applications.

Metalloids are typically brittle solids at room temperature and may have a metallic luster or a dull appearance. Their chemistry is diverse: many form covalent bonds and possess oxides that are amphoteric. The exact set of elements regarded as metalloids varies by source, but the most commonly cited examples are boron, silicon, germanium, arsenic, antimony, tellurium, polonium, and astatine. Some sources also include selenium or other elements in certain classifications.

Applications of metalloids stem largely from their semiconducting properties. Silicon and germanium are foundational for electronics, used in diodes, transistors, integrated circuits, and solar cells. Boron and phosphorus are important dopants that modify electrical conductivity in semiconductors. Tellurium and antimony find use in thermoelectric materials and specialized alloys. Polonium and astatine are extremely rare and highly radioactive, limiting their practical use to niche or research contexts.

Safety and environmental considerations vary by element. Arsenic is toxic and a health concern in some environments, while polonium is highly radioactive. Astatine is exceedingly rare and radioactive. Because metalloids can exhibit a range of chemical behaviors, proper handling and context-specific guidance are essential in their study and use.

Historically, the term and classification of metalloids emerged in the 19th and 20th centuries as scientists sought to describe elements with properties that did not fit neatly into metals or nonmetals.