Metalloid Elements: Properties and Examples

Yash Solanki, Megan Wahl
  • Author
    Yash Solanki

    Yash Solanki has taught post-secondary science for over four years. He has a bachelors degree in Biology from Iowa State University, and has worked as a scientific researcher at multiple global institutions.

  • Instructor
    Megan Wahl

    Megan has taught middle school science and developed curriculum for k-higher ed. She has a master's degree in Educational Technology.

What are metalloid elements? Find examples of metalloids and learn about the location of metalloids on the periodic table and the properties of metalloids. Updated: 07/20/2021

Table of Contents


What are Metalloid Elements?

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:

  • Boron
  • Silicon
  • Germanium
  • Arsenic
  • Antimony
  • Tellurium

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.

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  • 0:00 The Periodic Table
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Location of Metalloids on the Periodic Table

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.

Periodic table of elements with the six metalloid elements (beginning with boron (B)) marked with a beige color. This group sometimes also includes the elements bismuth (Bi), polonium (Po), and astatine (At) from period 6 of the table.

Metalloids on 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.

Properties of Metalloids

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.

Physical Properties

The physical properties of metalloid elements include:

  • They exist in the solid state of matter at room temperature and pressure
  • They have a metallic luster (a metal-like appearance)
  • They are brittle (not malleable or ductile, i.e. cannot be shaped under pressure or into wires respectively)
  • They are semiconductors (certain conditions, such as heating a metalloid up, allows its electrons to flow freely, and it will temporarily act as a conductor. Cooling it may make it behave more like an insulator.)
  • Melting point and boiling point varies between the individual metalloid elements

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.

This photo of the metalloid silicon (Si) shows the metallic luster characteristic of the metalloid elements

Metalloid silicon

Chemical Properties

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:

  • Less than 4 valence electrons
  • Exactly 4 valence electrons
  • Greater than 4 valence electrons

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Frequently Asked Questions

How many metalloids are on the periodic table?

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.

What are 4 properties of metalloids?

The four major properties of metalloids are as follows:

- They are solids

- They have a metallic luster

- They are brittle

- They are semiconductors

What types of properties do metalloids display?

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.

Where are the metalloids on the periodic table?

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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