http://www.ck12.org Chapter 6. The Periodic Table
Metals, Nonmetals, and Metalloids
Elements can be classified in a number of different ways. Classifying by period and/or group is useful because it
is based on electron configuration. Another way is to classify elements based on physical properties. Three broad
classes of elements that are categorized in this way include metals, nonmetals, and metalloids.
Ametalis an element that is a good conductor of heat and electricity. Metals are also malleable, which means
that they can be hammered into very thin sheets without breaking, and ductile, which means that they can be drawn
into wires. When a fresh surface of any metal is exposed, it will be very shiny because it reflects light well. This
property is referred to as luster. All metals are solid at room temperature except mercury (Hg), which is a liquid. The
melting points of different metals vary widely. Mercury has the lowest melting point of all pure metals (−39°C),
and tungsten (W) has the highest (3422°C). On the periodic table (Figure6.4), the metals are shaded blue and
are located to the left of the bold stair-step line. About 80 percent of the elements are metals, which you can see
examples of below (Figure6.5).
FIGURE 6.5
The elements mercury, gold, and copper
display properties that are common of
metals. Mercury (left) is the only metal
that is a liquid at room temperature. Even
in its liquid form, it still has a high luster.
Gold (middle) is malleable and can be
formed into very thin sheets called gold
leaf. Because copper (right) is ductile,
inexpensive, and a good conductor, it is
used extensively in electrical wiring.Anonmetalis an element that is generally a poor conductor of heat and electricity. Many properties of nonmetals
are the opposite of those seen in metals. There is a wider variation in properties among the nonmetals than among
the metals, as pictured below (Figure6.6). Nonmetals exist in all three states of matter at room temperature. The
majority are gases, such as nitrogen and oxygen. Bromine is a liquid, and a few are solids, such as carbon and sulfur.
In the solid state, nonmetals are brittle, meaning that they will shatter if struck with a hammer. The solids are not
lustrous, and their melting points are generally much lower than those of metals. On the periodic table above, the
nonmetals are shaded green and appear to the right of the stair-step line.
FIGURE 6.6
Nonmetals have properties that are unlike
those of metals. Sulfur (left) is brittle,
and its distinctive yellow color lacks luster.
Bromine (center) is the only liquid non-
metal and must be carefully handled due
to its toxicity. Helium (right), a colorless
and unreactive gas, is lighter than air and,
thus, is used in blimps.