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SUPPLEMENTAL NOTES
Grade 8 – Physical Science - Mrs. Petit
Chapter # ____4__
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Title/Sub-Title
128
129
Nonmetals and
Metalloids
Properties of Nonmetals
129
Physical Properties
Section(s): _4_
Main Idea(s) of the Paragraph
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Chemical Properties
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Families of Nonmetals
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The Carbon Family
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The Nitrogen Family
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The Oxygen Family
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The Halogen Family
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The Noble Gases
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Compared to metals, nonmetals have a wider variety of properties.
A nonmetal is an element that lacks most properties of a metal.
Most nonmetals are poor conductors of electricity and heat and are
reactive with other elements. Solid nonmetals are dull and brittle.
Ten of the sixteen nonmetals on the periodic table are gases at room
temperature.
The physical properties of nonmetals are the opposite of metals.
Solid nonmetals are dull and brittle, and are also poor conductors of
heat and electricity.
Most nonmetals are reactive, so they often form compounds. In
fact, fluorine (F) is the most reactive element known.
Atoms of nonmetals usually gain or share electrons.
Only Group 18 of the periodic table contains elements that are all
nonmetals.
Groups 14 – 17 are a mixture of nonmetals and other kind of
elements.
In Group 14 (Carbon Family) on carbon(C) is a nonmetal.
Carbon is an especially important element due to its role in the
chemistry of life.
In Group 15 (The Nitrogen Family) there are two nonmetals. They
are nitrogen (N) and phosphorus (P).
Nitrogen is an example of an element that occurs in nature in the
form of a diatomic molecule (N2). A diatomic molecule consists of
two atoms.
Phosphorus is the other nonmetal in the nitrogen family. It is much
more reactive than nitrogen.
Group 16 (Oxygen Family) contains three nonmetals – oxygen (O),
sulfur (S), and selenium (Se).
Like nitrogen, oxygen is a diatomic molecule (O2). Oxygen can also
form a triatomic (three-atom) molecule (O3) which is called ozone.
Sulfur is the most common nonmetal in the oxygen family. Sulfur is
used in the making of rubber for rubber bands and car tires.
Group 17 contains four nonmetals – fluorine, chlorine, bromine, and
iodine. The elements in group 17 are know and the halogen, which
means “salt forming”.
All of the halogens are very reactive.
The elements in Group 18 are known as the noble gases. They do
not usually form compounds because they do not like to gain, lose,
or share electrons.
All of the noble gases exist in the Earth’s atmosphere, but only in
small amounts.
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Hydrogen
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Alone in the upper left corner of the periodic table is hydrogen.
Each hydrogen atom has one proton and one electron.
Because of chemical properties of hydrogen are very different than
those of other elements, it really isn’t grouped into a family.
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The Metalloids
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Along the border between the metals and nonmetals are seven
elements known as the metalloids.
The metalloids have some characteristics of both metals and
nonmetals. All are a solid at room temperature.
The most common metalloid is silicon.
The most useful property of the metalloids is their varying ability to
conduct electricity. (It can depend on the temperature, exposure to
light, or the presence of a small amount of impurities).
Semiconductors are substances that can conduct electricity under
some conditions but not under others. (used to make computer
chips, lasers, and transistors).
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