What are metalloids?

We explain what metalloids are and what their uses and characteristics are. In addition, the use of the term “semimetals”.

  1. What are metalloids?

Metalloids or semimetals are certain types of chemical elements , which exhibit an intermediate behavior between metallic and non-metallic elements, in terms of ionization issues and bonding properties. That is, they are elements that act as metals in some situations, and as nonmetals in others.

However, it is not easy to distinguish metalloids from true metals, and doing so generally requires a review of their electrical conduction properties , as they also tend to be very varied in shape, appearance and color.

The elements known as metalloids are the following:

  • Boron (B).
  • Silicon (Yes).
  • Germanium (Ge).
  • Arsenic (Ar).
  • Antimony (Sb).
  • Tellurium (Te).
  • Polonium (Po).
  • Astato (At).

These elements are, in the Periodic Table , distributed in a diagonal descending from the boron to the astatine, between columns 13, 14, 15, 16 and 17, thereby dividing the entire table into two. The elements located in the right half are the non-metallic ones and those located in the left half are the metallic ones.

Metalloids are more or less rare in the earth’s crust . Some are very abundant, such as silicon, which usually appears to form compounds called silicates, or also arsenic, or boron, found as part of the mineral borax, since it does not exist in a free and pure state in nature .

On the other hand, others such as polonium are quite rare and appear, in this case, as part of certain uranium minerals. Antimony, for example, is found in small percentages on planet Earth .

  1. Characteristics of metalloids

semi metal boron metalloids
Many metalloids such as boron are not found pure in nature.

The metalloids are very varied in terms of their appearance, that is, shape and color . Some are bright and others opaque , and many also have more than one allotropic state, that is, more than one presentation, depending on their molecular structure.

For example, the arsenic can be gray, yellow or black, depending on its allotropic version. Silicon, likewise, can be shown as a bright solid crystal, or as a brown and shapeless powder.

However, the metalloids are mostly electrical semiconductors , that is, they transmit electricity in only one direction, instead of complete conductors such as metallic elements. Even so, they are much better conductors than non-metal elements (which are usually insulating), which is why they have numerous industrial uses.

As with electricity, metalloids conduct heat much better than non-metallic elements , but without reaching the high conductivity of metals.

Such an intermediate condition allows metalloids to react differently, depending on whether they are in the presence of a metal (in that case they will react as a nonmetal) or a nonmetal (then they will react as a metal). In general, they are quite reactive elements, rarely found in pure form in nature and have three or more electrons in their last orbit.

For that same reason, they are usually toxic . Even some, such as arsenic, which are indispensable for the formation of vital molecules and are found in the body of living beings . In fact, boron or arsenic poisoning itself is usually lethal; while polonium, for example, is not only toxic, but highly radioactive.

  1. Uses of metalloids

semi metal silicon metalloids
Much of the chips and circuits are made of silicon.

For the most part, semimetals are useful in the manufacture of electronic devices and others that use semiconductors, such as rectifiers, transistors , diodes, integrated circuits or even, in the case of silicon, for chips and microprocessors present in virtually all the devices we use. today.

However, being so varied, the metalloids have other different uses, as part of pesticides , sealing materials or catalysts , such as some boron isotopes, for example, useful in the absorption of neutrons within nuclear power plants, functioning as agents of regulation of atomic reactions.

  1. Semimetals or metalloids?

Both terms are correct when naming this type of chemical elements: metalloids (that is, similar to metal) or semimetals (that is, they do not become entirely a metal). They can be used interchangeably.

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