The Xometry app works best with JavaScript enabled!
  • Solutions
  • Industries
  • Resources
  • Enterprise
  • How Xometry Works
  • Become a Supplier
ResourcesMaterials6 Properties of Metalloids

6 Properties of Metalloids

Picture of Dean McClements
Written by
Aaron Lichtig
Updated by
 4 min read
Published August 8, 2022
Updated September 18, 2024

Learn more about the key properties of these elements.

Fine antimony on white background. Image Credit: Shutterstock.com/Bjoern Wylezich

Metalloids are a class of elements that have properties of both metals and nonmetals. They fall between metals and nonmetals on the periodic table. The definition of metalloids, as well as the number of elements that fall into the metalloids group, is often argued by scientists. Boron, silicon, germanium, arsenic, tellurium, and antimony are all generally accepted as being metalloid elements, and as such, will be the focus of this article. However, while polonium, astatine, and bismuth are also sometimes classified as metalloids, they will not be discussed.

This article will describe the six most important properties of metalloids and list some key metalloids characteristics.

1. Metalloids Are Solids

All metalloids are solid at room temperature and have relatively high melting points. The melting points of the metalloids are listed in Table 1 below:

Table 1. Melting Temperatures of Metalloids
ElementMelting Temperature (°C)
Element

Boron

Melting Temperature (°C)

2079

Element

Silicon

Melting Temperature (°C)

1410

Element

Germanium

Melting Temperature (°C)

938.3

Element

Arsenic

Melting Temperature (°C)

817

Element

Tellurium

Melting Temperature (°C)

449.5

Element

Antimony

Melting Temperature (°C)

631

2. Metalloids Have a Metallic Luster and Appear to be Metals

Metalloids have the physical appearance of metals. Their metallic/reflective surface makes it immediately obvious why the name "metalloid" fits these elements. The image below illustrates the visible surface characteristics of metalloids:

Metalloids appearances
The physical appearance of different metalloids

3. Metalloids Are Brittle and Easily Broken

Metalloids cannot be formed using the cold-forming techniques normally used for metals because they are very brittle. Metalloids will tend to fail due to brittle fracture or crumbling. 

4. Metalloids Have the Ability To Conduct Electricity, but Not As Well as Metals

Metalloids can be manipulated to behave as either conductors or insulators. This semiconducting behavior is what makes some, if not all, metalloids so useful in controlling complex electronic circuits. Metalloids are modified into semiconductors useful for a wide range of circumstances by a process called "doping." Doping is the process of adding impurities to alter the properties of intrinsic semiconductors, like metalloids. Despite their valuable semiconducting capabilities, metalloids are still poor conductors of electricity compared to metals.

5. Metalloids Behave More Like Nonmetals in That They Easily Form Anions, Have Multiple Oxidation States, and Form Covalent Bonds

The oxidation state of an element refers to the number of electrons an atom either gains or loses to bond chemically with another atom. In the case of metalloids, single covalent bonds are more common. A covalent bond refers to the situation where a pair of atoms share one electron. The oxidation states of the metalloid elements are listed in Table 3 below: 

Table 3. Metalloids’ Oxidation States
ElementsOxidation States
Elements

Oxidation States

Positive

Elements

Boron

Oxidation States

+3, +2, +1

Elements

Silicon

Oxidation States

+4, 0

Elements

Germanium

Oxidation States

+2, +4

Elements

Arsenic

Oxidation States

+3, +5

Elements

Tellurium

Oxidation States

+4, +6

Elements

Antimony

Oxidation States

+3, +5

6. Metalloids' Ionization Energies and Electronegativities Are In Between the Values of Metals and Nonmetals

“Ionization energy” refers to the amount of energy that is required to strip an electron from a neutral atom to form an ion. The first ionization energy is the energy required to strip off the first electron - this is the easiest electron to strip. Electronegativity refers to how easily an atom will attract elements when forming a chemical bond. The higher the number, the stronger the attraction. Therefore, the higher the value for electronegativity, the more likely it is that the element will attract electrons. If two elements with similar electronegativities bond, they will form a pure covalent bond that equally shares the electrons. However, if elements have different electronegativities, the resulting molecule will be polarized. This is because the electrons in the bond will be attracted more to the stronger electronegativity element. The metalloids listed in Table 4 below have ionization energies and electronegativities as shown:

Table 4. Metalloids’ 1st Ionization Energies and Electronegativities
Elements1st Ionization Energy (eV)Electronegativity (Pauling Scale)
Elements

Boron

1st Ionization Energy (eV)

8.298

Electronegativity (Pauling Scale)

2.04

Elements

Silicon

1st Ionization Energy (eV)

8.1517 

Electronegativity (Pauling Scale)

1.9

Elements

Germanium

1st Ionization Energy (eV)

7.9

Electronegativity (Pauling Scale)

2.01

Elements

Arsenic

1st Ionization Energy (eV)

9.8152

Electronegativity (Pauling Scale)

2.18

Elements

Tellurium

1st Ionization Energy (eV)

9.0096

Electronegativity (Pauling Scale)

2.1

Elements

Antimony

1st Ionization Energy (eV)

8.64

Electronegativity (Pauling Scale)

2.05

Distinguishing Properties of Metalloids

The key distinguishing properties of metalloids are that they have characteristics of both metals and nonmetals. Their ability to act as semiconductors is an important and unique feature of some metalloids. This makes metalloids indispensable in an era when electronic circuits are everywhere.

The elements that are commonly referred to as metalloids are listed in Table 5, along with brief descriptions and a few typical applications:

For more information, see our guide on the Elements of Metalloids.

Table 5. Metalloids: Descriptions and Typical Applications
ElementDescriptionApplication
Element

Boron

Description

An allotropic semimetal that is extremely hard and heat resistant. Has an atomic number of 5.

Application

Used with silicon to make thermal shock-resistant glass.

Element

Silicon

Description

A gray and shiny semiconductive metal. It has high melting (1,410 °C) and boiling points (3,265 °C). Has an atomic number of 14.

Application

Commonly used for semiconductors.

Element

Germanium

Description

Is hard and brittle in its elemental form. Has an atomic number of 32.

Application

Less commonly used for semiconductors.

Element

Arsenic

Description

A steel-gray semimetal known for being poisonous. It has an atomic number of 33.

Application

Often used as an insecticide.

Element

Tellurium

Description

Brittle in its elemental form. It is a chalcogen, along with selenium and sulfur. It has an atomic number of 52.

Application

Used as a steel additive to improve machinability.

Element

Antimony

Description

A hard, and brittle semimetal with an atomic number of 51.

Application

Used to color paints;  often alloyed with lead.

Differences Between Metals and Nonmetals

Some differences between metals and nonmetals are shown in table 6 below:

Table 6. Comparison of Metals and Nonmetals 
PropertiesMetalsNonmetals
Properties

Electrical Conductivity

Metals

Generally conductive

Nonmetals

Nonconductive; behave as insulators

Properties

Mechanical Properties

Metals

Can be hard or soft, ductile or brittle.

Nonmetals

Generally brittle and hard, not suitable for mechanical applications

Properties

Thermal Conductivity

Metals

Metals are more thermally conductive than nonmetals

Nonmetals

Nonmetals are not very thermally conductive

Properties

Form

Metals

Most metals are solids at room temperature (barring a few exceptions like gallium or mercury)

Nonmetals

Nonmetals can be in the form of gasses (e.g., hydrogen), liquids (e.g.,  bromine),  or solids (e.g.,  carbon)

Ready to Get a Quote?

Take advantage of our network and see what Xometry can do for you.

Summary


Xometry provides a wide range of manufacturing capabilities including 3D printing, CNC machining, laser cutting, and injection molding. Get your instant quote today. Xometry, where big ideas are built.

Disclaimer

The content appearing on this webpage is for informational purposes only. Xometry makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by third-party suppliers or manufacturers through Xometry’s network. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please refer to our terms and conditions for more information.

Picture of Dean McClements
Dean McClements
Dean McClements is a B.Eng Honors graduate in Mechanical Engineering with over two decades of experience in the manufacturing industry. His professional journey includes significant roles at leading companies such as Caterpillar, Autodesk, Collins Aerospace, and Hyster-Yale, where he developed a deep understanding of engineering processes and innovations.

Read more articles by Dean McClements

Quick Links

  • Home

  • Contact Us

  • Help Center

  • About Us

  • Careers

  • Press

  • Investors

  • Xometry Go Green

Support

  • Privacy Policy | Terms of Use | Legal

  • ITAR | ISO 9001:2015 | AS9100D | ISO 13485:2016 | IATF 16949:2016


© 2024 Xometry, All Rights Reserved