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Metals
Chapter 3 Section 2
What is a Metal?
 Think of a familiar metal such as iron, tin, gold,
or silver. How would you describe it?
 Chemists classify an element as a metal based
on physical properties such as hardness,
shininess, malleability, ductility.
 Polished silver is a good example of shininess.
 A malleable material is one that can be pounded
into shapes.
 A ductile material is one that can be pulled out
or drawn into a long wire. Copper sheeting or
wire can be made because of copper’s
malleability and ductility.
Physical Properties of Metals
 Most metals are good conductors because
they transmit heat and electricity easily.
 A metal that is attracted to a magnet or can
be made into a magnet are described as
magnetic. Iron, cobalt, and nickel are
examples of magnetic metals.
 Most metals are solids at room temperatures.
 You would need to raise the temperature of
some metals as high as 3,400 C to melt them.
 Mercury is an exception to this because it is a
liquid at room temperature.
Chemical Properties of Metals
 Metals show a wide range of chemical properties.
 The ease and speed with which an element, combines
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or reacts, with other elements and compounds is called
its reactivity.
For example, sodium and potassium will react if
exposed to air or water.
To prevent this, they must be stored under oil in sealed
containers.
In comparison, gold and chromium are unreactive.
Gold is valued because it stays shiny instead of
reacting with air and chromium is plated on objects left
outdoors (automobile trim) because it is extremely
slow to react with air and water.
Corrosion
 A metal that wears away as the soft metal
oxide flakes off is called corrosion.
 If iron is left unprotected, its surface will slowly
turn to reddish-brown rust.
 A mixture of metals is called an alloy.
 Useful alloys combine the best properties of
two or more metals into a single substance.
 For example, brass is an example of an alloy of
copper and zinc.
 Pure iron rusts easily but when mixed with
carbon, chromium and vanadium, iron forms
stainless steel.
Metals in the Periodic Table
 The metals in a group, or family, have
similar properties, and these family
properties change gradually as you
move across the table.
 The reactivity of the metals tends to
decrease as you move from left to right
across the periodic table.
Alkali Metals
 The metals in Group 1, from lithium to
francium are called the alkali metals.
 These metals are so reactive that they are
never found as elements but only in
compounds.
 In the lab, however, scientists have been able
to isolate the pure, uncombined forms.
 As pure elements, the alkali metals are very
soft and shiny.
 They are so soft, that you could cut them with
a plastic knife.
Sodium and Potassium
 The two most important alkali metals are sodium and
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potassium.
Sodium compounds are found in large amounts of
sea water and sea beds.
Our diets include many compounds that contain
sodium and potassium. Both are essential to life.
Alkali metals are so reactive because each atom only
has one valence electron that is easily transferred to
another atom during a chemical change.
When the valence electron is gone, the part of the
atom that remains is much more stable.
Alkaline Earth Metals
 Group 2 of the periodic table contains the
alkaline earth metals.
 These metals are not as reactive as group 1,
but are more reactive than most metals.
 They are never found uncombined in nature.
 They are fairly hard, gray-white and good
conductors of electricity.
Magnesium and Calcium
 Magnesium and calcium are the most common
alkaline earth metals.
 Magnesium was once used in flash bulbs
because it gives off a very bright light when it
burns.
 When combined with aluminum, magnesium
makes a strong, lightweight alloy.
 We use it for making ladders, airplane parts, etc.
 Calcium is essential for our teeth and bones. It
also helps our muscles to work properly.
 Calcium is found in milk and other dairy products
as well as leafy green vegetables.
Transition Metals
 The elements in Group 3 through 12 are called
the transition metals.
 The transition metals bridge between the very
reactive and less reactive metals.
 Transition metals are so similar to one another
that differences between them are difficult to
detect.
 Transition metals include iron, copper, nickel,
silver, and gold.
 Most transition metals are hard and shiny
 All of the transition metals are good conductors
of electricity.
Transition metals cont.
 The transition metals are fairly stable,
reacting slowly or not at all to water or air.
 Ancient gold coins and jewelry are as
beautiful and detailed today as they were
thousands of years ago.
 Transition metals are found in our bodies.
We could not survive without iron.
 Iron is an important part of a large molecule
called hemoglobin, which carries oxygen in
our bloodstream. Hemoglobin is what gives
blood its bright red color.
Metals in Mixed Groups
 Groups 13 - 16 include metals, nonmetals, and
metalloids.
 The metals in these groups are nearly as
reactive as those on the left side of the table.
 The most familiar of these metals are
aluminum, tin and lead.
 Aluminum is the lightweight metal used in soda
cans, tin is used to coat steel to protect it from
corrosion in cans of food. Lead is a shiny, bluewhite metal that was used in paints and water
pipes. Lead is no longer used for these
purposes because it is poisonous.
Lanthanides and Actinides
 The elements at the bottom of the
periodic table are called the lanthanides
and actinides.
 They are also known as the rare earth
elements.
 These elements fit in Periods 6 and 7
between the alkaline earth metals and
the transition metals.
Lanthanides
 Lanthanides are soft, malleable, shiny metals
with high conductivity.
 They are used in industry to make various
alloys.
 Different lanthanides are usually found
together in nature.
 They are difficult to separate from one
another because all of them have very similar
properties.
Actinides
 Of the actinides, only thorium and
uranium exist on Earth.
 Uranium is used to produce energy in
nuclear power plans.
 All of the elements after uranium were
produced artificially in laboratories.