Definition Of Metalloids
The elements which possess the character of both metals and non – metals are called as metalloids
More About Metalloids
- The metalloids or semimetals are located along the line between the metals and nonmetals in the periodic table
- The metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium
- Other elements less commonly recognized as metalloids include carbon, aluminium, selenium, polonium and astatine
- The electronegativities and ionization energies of the metalloids are between those of the metals and nonmetals
- The metalloids exhibit characteristics of both classes
- Silicon, possesses a metallic luster, yet it is an inefficient conductor and is brittle
- The reactivity of the metalloids depends on the element with which they are reacting
- Boron acts as a nonmetal when reacting with sodium yet as a metal when reacting with fluorine
- The boiling points, melting points, and densities of the metalloids vary widely
- The intermediate conductivity of metalloids means they make good semiconductors
- On a periodic table all of these elements can be found in or near a diagonal region of the p-block
- Chemically, they mostly behave as weak nonmetals
- They can, however, form alloys with metals.
- Some properties of metalloids are
- Electronegativities between those of metals and nonmetals
- Ionization energies between those of metals and nonmetals
- Possess some characteristics of metals/some of nonmetals
- Reactivity depends on properties of other elements in reaction
- Often make good semiconductors
- Metalloids generally form amphoteric oxides
- Some allotropes of elements exhibit more pronounced metal, metalloid or non-metal behavior than others
- For example, for the element carbon, its diamond allotrope is a non metal and graphite allotrope displays limited electrical conductivity which is a more characteristic of a metalloid
- Phosphorus, selenium, tin, and bismuth also have allotropes that display borderline behavior
Uses of Metalloids:
- All the elements commonly recognized as metalloids (or their compounds) have found application in the semiconductor or solid-state electronic industries
- Arsenic has been used as a pharmaceutical agent since antiquity and notably for the treatment of syphilis prior to the development of antibiotics
- Compounds of antimony are used as ant protozoan drugs, and in some veterinary preparations
- Boron is used in insecticides and herbicides. It is a trace element. As boric acid, it also has antiseptic, antifungal, and antiviral properties
- Silicon can be applied to badly burned patients, in the form a silicone gel, to reduce scarring
- Tellurium is not an essential element. Tellurium dioxide has been used to treat seborrhea dermatitis
- lead arsenate, has been extensively used as an insecticide
