Groups with Metalloids
Jean Brainard, Ph.D.
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Printed: February 28, 2013
AUTHOR
Jean Brainard, Ph.D.
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C ONCEPT
Concept 1. Groups with Metalloids
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Groups with Metalloids
• Identify elements in groups 13–16 of the periodic table.
• List properties of a metalloid from each of these groups.
This image represents a famous ancient Egyptian named Tutankhamen. Do you see his heavy eyeliner? Most
likely the eyeliner was made of a mineral containing antimony. This metalloid was commonly used for makeup by
Egyptians between four and five thousand years ago. Today we know that antimony is toxic, although Tutankhamen
probably didn’t know that. Antimony is found in group 15 of the periodic table. Group 15 is one of four groups of
the periodic table that contain metalloids.
Groups 13–16
Groups 13–16 of the periodic table (orange in the Figure 1.1) are the only groups that contain elements classified
as metalloids. Unlike other groups of the periodic table, which contain elements in just one class, groups 13–16
contain elements in at least two different classes. In addition to metalloids, they also contain metals, nonmetals, or
both. Groups 13–16 fall between the transition metals (in groups 3–12) and the nonmetals called halogens (in group
17).
What Are Metalloids?
Metalloids are the smallest class of elements, containing just six members: boron (B), silicon (Si), germanium
(Ge), arsenic (As), antimony (Sb), and tellurium (Te). Metalloids have some properties of metals (elements that can
conduct electricity) and some properties of nonmetals (elements that cannot conduct electricity). For example, most
metalloids can conduct electricity, but not as well as metals. Metalloids also tend to be shiny like metals, but brittle
like nonmetals. Chemically, metalloids may behave like metals or nonmetals, depending on their number of valence
electrons. You can learn more about specific metalloids by clicking on the element symbols in the periodic table at
this URL: http://www.chemicool.com/.
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FIGURE 1.1
Q: Why does the chemical behavior of an element depend on its number of valence electrons?
A: Valence electrons are the electrons in an atom’s outer energy level that may be involved in chemical reactions
with other atoms.
Group 13: Boron Group
Group 13 of the periodic table is also called the boron group because boron (B) is the first element at the top of
the group . Boron is also the only metalloid in this group. The other four elements in the group—aluminum (Al),
gallium (Ga), indium (In), and thallium (Tl)—are all metals. Group 13 elements have three valence electrons and
are fairly reactive. All of them are solids at room temperature.
Group 14: Carbon Group
Group 14 of the periodic table is headed by the nonmetal carbon (C), so this group is also called the carbon group.
Carbon is followed by silicon (Si) and germanium (Ge), which are metalloids, and then by tin (Sn) and lead (Pb),
which are metals. Group 14 elements group have four valence electrons, so they generally aren’t very reactive. All
of them are solids at room temperature.
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Concept 1. Groups with Metalloids
FIGURE 1.2
Germanium is a brittle, shiny, silverywhite metalloid.
Along with silicon, it
is used to make the tiny electric circuits
on computer chips.
It is also used to
make fiber optic cables—like the ones
pictured here—that carry telephone and
other communication signals.
Group 15: Nitrogen Group
Group 15 of the periodic table is also called the nitrogen group. The first element in the group is the nonmetal
nitrogen (N), followed by phosphorus (P), another nonmetal. Arsenic (As) and antimony (Sb) are the metalloids in
this group, and bismuth (Bi) is a metal. All group 15 elements have five valence electrons, but they vary in their
reactivity. Nitrogen, for example, is not very reactive at all, whereas phosphorus is very reactive and found naturally
only in combination with other substances. All group 15 elements are solids, except for nitrogen, which is a gas.
Group 16: Oxygen Group
Group 16 of the periodic table is also called the oxygen group. The first three elements—oxygen (O), sulfur (S), and
selenium (Se)—are nonmetals. They are followed by tellurium (Te), a metalloid, and polonium (Po), a metal. All
group 16 elements have six valence electrons and are very reactive. Oxygen is a gas at room temperature, and the
other elements in the group are solids.
FIGURE 1.3
Tellurium is a silvery white, brittle metalloid.
It is toxic and may cause birth
defects. Tellurium can conduct electricity
when exposed to light, so it is used to
make solar panels. It has several other
uses as well. For example, it makes steel
and copper easier to work with and lends
color to ceramics.
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Q: With six valence electrons, group 16 elements need to attract two electrons from another element to have a stable
electron arrangement of eight valence electrons. Which group of elements in the periodic table do you think might
form compounds with elements in group 16?
A: Group 2 elements, called the alkaline Earth metals, form compounds with elements in the oxygen group. That’s
because group 2 elements have two valence electrons that they are “eager” to give up. An example of a group 2 and
group 6 compound is calcium oxide (CaO).
Summary
• Groups 13–16 of the periodic table contain one or more metalloids, in addition to metals, nonmetals, or both.
• Group 13 is called the boron group, and boron is the only metalloid in this group. The other group 13 elements
are metals.
• Group 14 is called the carbon group. This group contains two metalloids: silicon and germanium. Carbon is
a nonmetal, and the remaining elements in this group are metals.
• Group 15 is called the nitrogen group. The metalloids in this group are arsenic and antimony. Group 15 also
contains two nonmetals and one metal.
• Group 16 is called the oxygen group. Tellurium is the only metalloid in this group, which also contains three
nonmetals and one metal.
Vocabulary
• metalloid: Class of elements that have some properties of metals and some properties of nonmetals.
Practice
Watch the video at the following URL, and then answer the questions below.
http://www.youtube.com/watch?v=NO36yksPOBM (6:50)
MEDIA
Click image to the left for more content.
1. Why does boron act chemically like a metal?
2. Why do arsenic, antimony, and tellurium tend to have chemical properties similar to nonmetals?
3. Sometimes silicon and germanium behave like metals, and sometimes they behave like nonmetals. Explain
why.
Review
1.
2.
3.
4.
Which elements in groups 13–16 are metalloids?
Name two physical properties that boron shares with most metals.
What property of the metalloid silicon makes it useful for computer chips?
A recent investigation found relatively high levels of the metalloid arsenic in samples of apple juice. Why
might this be a serious problem?
5. Why is the metalloid tellurium used to make solar panels?
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