Metalloids
Jean Brainard, Ph.D.
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Printed: July 27, 2013
AUTHOR
Jean Brainard, Ph.D.
www.ck12.org
C ONCEPT
Concept 1. Metalloids
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Metalloids
• Define metalloid.
• List common metalloids and give their uses.
Have you ever taken a multiple-choice test?
Most of the time the answers are specific choices – is the answer possibility a or possibility b? Quite often you can
“think through” the choices to come up with the correct answer. More frustrating is the choice “none of the above.”
You feel very uncertain checking that possibility.
Metalloids
Some elements are “none of the above.” They don’t fit neatly into the categories of metal or non-metal because of
their characteristics. A metalloid is an element that has properties that are intermediate between those of metals and
nonmetals. Metalloids can also be called semimetals. On the periodic table, the elements colored yellow, which
generally border the stair-step line, are considered to be metalloids. Notice that aluminum borders the line, but it is
considered to be a metal since all of its properties are like those of metals.
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Examples of Metalloids
Silicon is a typical metalloid. It has luster like a metal, but is brittle like a nonmetal. Silicon is used extensively in
computer chips and other electronics because its electrical conductivity is in between that of a metal and a nonmetal.
Boron is a versatile element that can be incorporated into a number of compounds. Borosilicate glass is extremely
resistance to thermal shock. Extreme changes in the temperature of objects containing borosilicates will not create
any damage to the material, unlike other glass compositions, which would crack or shatter. Because of their
strength, boron filaments are used as light, high-strength materials for airplanes, golf clubs, and fishing rods. Sodium
tetraborate is widely used in fiberglass as insulation and also is employed in many detergents and cleaners.
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Concept 1. Metalloids
Arsenic has long played a role in murder mysteries, being used to commit the foul deed. This use of the material
is not very smart since arsenic can be easily detected on autopsy. We find arsenic in pesticides, herbicides,
and insecticides, but the use of arsenic for these applications is decreasing due to the toxicity of the metal. Its
effectiveness as an insecticide has led arsenic to be used as a wood preservative.
Antimony is a brittle, bluish-white metallic material that is a poor conductor of electricity. Used with lead, antimony
increases the hardness and strength of the mixture. This material plays an important role in the fabrication of
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electronic and semiconductor devices. About half of the antimony used industrially is employed in the production
of batteries, bullets, and alloys.
Summary
• Metalloids are elements with properties intermediate between those of metals and non-metals
• Silicon is a metalloid because it has luster, but is brittle.
• Boron, arsenic, and antimony are metalloids with a variety of uses.
Practice
Use the link below to answer the following:
http://www.buzzle.com/articles/uses-of-metalloids.html
1. Describe the physical properties of two metalloids of your choosing.
2. List two uses for each of these metalloids.
Review
1.
2.
3.
4.
5.
6.
Define “metalloid.”
Why would it be difficult to decide whether or not an element was a metalloid?
Why is silicon used extensively in electronics?
What are borosilicates used for?
Why is the use of arsenic as an insecticide decreasing?
What is a main application of antimony?
• metalloid: An element that has properties that are intermediate between those of metals and nonmetals.
• luster: A reflective surface.
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Concept 1. Metalloids
References
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Image copyright WilleeCole, 2013. MultipleChoice. Used under license from Shutterstock.com
CK-12 Foundation - Christopher Auyeung. Periodic Table. CC-BY-NC-SA 3.0
User:Enricoros/Wikipedia. Silicon. Public Domain
User:Jurii/Wikimedia Commons. Boron. CC-BY 3.0
Aram Dulyan (Wikimedia: Aramgutang). Arsenic. Public Domain
Aram Dulyan (Wikimedia: Aramgutang). Antimony. Public Domain
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