Comparing Physical Properties of Metals,
Metalloids and Nonmetals
Periodic Table of the Elements
The periodic table separates the
elements into three groups: metals,
nonmetals, and metalloids. A stairstep line separates the metals from
the nonmetals. Most elements on
the table are metals. The metals
are located on the left side of the
periodic table. Nonmetals are
located on the right side of the
periodic table. The elements located
along the stair-step line are metalloids.
Properties of Metals
Most metals are solid at room temperature. Metals tend to be shiny. You
can see your reflection in a mirror because light reflects off the shiny
surface of a thin layer of silver behind the glass. Most metals are ductile,
which means that they can be drawn into thin wires. All metals are good
conductors of electric current. The wires in
the electrical devices in your home are made
of copper. Most metals are malleable, which
means that they can be flattened with a
hammer and will not shatter. Aluminum is
flattened into sheets to make cans and foil.
Most metals are good conductors of thermal
energy. An iron skillet conducts thermal
energy from a stovetop to cook your favorite foods.
32
Ge
Germaniun
m
84
Po
Polonium
Properties of Nonmetals
Nonmetals are very different from metals. There are only 17 nonmetals
and more than half of the nonmetals are gases at room temperature. Many
properties of nonmetals are the opposite of the
properties of metals. Nonmetals are NOT malleable
or ductile. In fact, solid nonmetals, such as carbon in
the graphite of a pencil lead, are brittle and will
break or shatter when hit with a hammer. Sulfur,
like most nonmetals, is dull or not shiny. Nonmetals
are poor conductors of thermal energy and electric current so they are
known as insulators. If the gap in a spark plug is too wide, the nonmetals
nitrogen and oxygen in the air will stop the spark and a car’s engine will not
run.
Properties of Metalloids
Metalloids have some properties of metals
and some properties of nonmetals. Some
metalloids are also called semiconductors.
This means that they can carry an electrical
charge under certain conditions. This
property of metalloids makes them useful in
calculators and computers. Tellurium is one of
the metalloids. It is shiny, but it is brittle
and can easily be smashed into a powder.
Boron, another metalloid, is almost as hard as diamond, but it is also very
brittle. At high temperatures, it is a good conductor of electric current.
Exceptions
The periodic table is useful when classifying elements as metals,
nonmetals, or metalloids, but watch out for a few exceptions. Metals are
all solids except for Mercury (Hg) which is liquid at room temperature.
Hydrogen (H) is on the left side of the periodic table, but it is a nonmetal.
Aluminum (Al) touches the stair-step line, but it is actually a metal.