Table of Contents
- What are Metalloid Elements?
- Location of Metalloids on the Periodic Table
- Properties of Metalloids
- Examples of Metalloids
- Lesson Summary
Metalloid elements, also known as semimetals, are elements that have properties of both metals and nonmetals. The metalloid definition is considered to include between six to nine elements that occur along a slanted line between the metal and nonmetal elements of the periodic table. The six elements that are unanimously considered to be metalloids are the following:
Apart from these six elements, the definition of metalloid elements sometimes includes the elements bismuth, polonium, and astatine as well. This ambiguity is in large part due to a lack of specific properties that are considered characteristics of all metalloids. Instead, the metalloid elements are simply characterized as having a mix of properties that are in between the properties of metals and nonmetals. Structurally, they form covalent bonded crystal structures, which is a characteristic found primarily in non-metals. One well-known use of some metalloid elements is as a semiconductor found inside many of the electronic devices that are used in every household.
As previously mentioned, metalloids are a group of elements that occur in a slanted line between the metals and nonmetals on the periodic table. This line of metalloid elements spans between Group 13 to Group 16, 17, or 18 (depending on how many elements are considered to be metalloids truly). To the left of this line of metalloid elements are the elements classified as metals, and to its right are elements classified as non-metals. The one exception to this rule is the element hydrogen, which is classified as a nonmetal but occurs on the left side of the periodic table.
The classifications of elements as metals, metalloids, or nonmetals are made on the basis of certain properties that are common to elements in each group.
Metalloids are defined as elements that have properties that are intermediate between the properties of nonmetals and metals. However, as seen by the ambiguity in the number of elements classified as metalloids, metalloid properties can have some variation between individual elements, which is why they are generally hard to characterize.
The major properties found in most metalloid elements can be divided into physical properties and chemical properties.
The physical properties of metalloid elements include:
The solid state of matter and metallic luster are characteristics that are also observed in most metal elements. However, metalloids are also brittle and semiconductors, which are considered properties similar to nonmetal elements. Hence, it can be seen that the physical properties of metalloids are a mix of characteristics of metals and nonmetals.
The chemical properties of metalloid elements generally vary based on the number of valence electrons, which are the electrons found in the outermost electron shell of the element. There are three distinct categories of metalloid elements based on the number of valence electrons, and the chemical properties within each category are fairly similar. These categories are:
For example, with only 3 electrons in its valence shell, boron tends to act as an electron donor in chemical reactions. This makes its reactivity and electronegativity similar to that of metals. On the other hand, elements such as arsenic or antimony - i.e., elements with greater than four valence electrons - tend to accept electrons. This makes them more similar to nonmetal elements in their reactions and electronegativity. There are also two metalloid elements - silicon and germanium - which have exactly four valence electrons. These elements can act either as a metal (by giving up electrons) or nonmetal (by accepting electrons) depending on the other elements involved in the chemical reaction.
In general the ionization energies of metalloids lie between the metal and non-metal elements in their periods. They also react readily with halogens, such as chlorine and fluorine, and in mixtures with metals they form alloys.
Many metalloid elements are widely used for industrial and commercial applications. Some examples of metalloids and their uses include:
Metalloid elements are elements with properties of both metals and nonmetals. The elements classified as metalloids are - boron, silicon, germanium, arsenic, antimony, and tellurium (and sometimes bismuth, polonium, and astatine). These elements occur along a slanted line between Group 13 and Group 16/17/18 of the periodic table, separating the metal elements from the nonmetal elements.
Properties of metalloids vary between the elements, sharing some similarities with both metals and nonmetals. Physical properties shared by all metalloids include:
Other properties such as melting point, boiling point, and chemical reactivity/electronegativity vary between the elements. Depending on the number of valence electrons, some metalloids react like metals, some react like nonmetals, and some as either metals or nonmetals, depending on the elements involved in the reaction.
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There are six elements generally accepted to be metalloids. However, based on the classification criteria being used, the exact number may vary, ranging from six to nine elements.
The four major properties of metalloids are as follows:
- They are solids
- They have a metallic luster
- They are brittle
- They are semiconductors
Metalloid element properties include a mixture of properties of both metals and nonmetals. While some characteristics (such as their metallic luster) are similar to metals, others (such as their brittleness) are similar to nonmetals.
The metalloids are located along a slanted line between the metal elements and nonmetal elements of the periodic table. They span from Group 13 to Group 16, 17, or 18 based on what criteria of classifying metalloid elements is being used.
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