EARTHLIGHTEST METAL THAT IS
LIQUID NEAR ROOM TEMPERATURE
Discovered in 18 75, the unusual metal gallium (Ga) possesses
an atomic number of 31 and melts at just 29.76 0 C (85.56 0 F).
Unlike liquid mercury, which is highly toxic, gallium is safe
to handle and will melt in your hand. These properties have
made it a key ingredient of a popular practical joke among
some chemists, who serve tea with a gallium spoon that
rapidly disappears upon stirring.SOFTEST METALLIC ELEMENT
With a Mohs value of just 0.2, caesium (Cs) is soft enough
to be cut with a butter knife. It melts at just 280 C (82 0 F)
and explodes violently when dropped in water. Caesium
was discovered in 1860 by the German scientists Robert
Bunsen and Gustav Kirchhoff, who isolated it from a sample
of mineral water using the recently developed technique of
flame spectroscopy. Silvery-gold in colour, caesium’s most
notable use is in super-accurate atomic clocks.
HEAVIEST ALKALINE
EARTH METAL
The alkaline earth metals
occupy group two of the
periodic table. They all
occur naturally and have
a shiny, silvery-white
appearance. The heaviest
is radium (Ra), with an
atomic number of 88.
Discovered by Marie and
Pierre Curie (both FRA)
in 1898, it is the only
radioactive member of
the alkaline earth metals.
Radium is used in
industrial imaging and
radioluminescent devices.
HIGHEST BOILING
POINT OF ANY METAL
As established by the
International Tungsten
Industrial Association
(ITIA), Tungsten (W)
has a boiling point of
5,700 0C (10,292 0 F), with
a 2000 C (3920F) margin
of error each side. This is
equivalent to the surface
temperature of the Sun.
Tungsten also has the
highest melting point
of any metal, at 3,422 0 C
(6,191 0F), with a 150 C
(59 0F) margin of error.
Its extraordinary heat
resistance makes tungsten
a useful metal for industrial
applications such as
drill-bits and furnaces.FIRST ALLOY
Alloys are mixtures of metals with other metals and
occasionally non-metallic substances. The first alloy
created by humans was bronze, which is copper mixed with
approximately 10% tin. The Bronze Age, which began in the
ancient Near East around the 4th millennium bce, marked
the period when this alloy became the material of choice for
weapons and tools. The era saw the development of mining
and smelting techniques, as well as the formation of trade
networks between early civilizations.
HARDEST METALLIC ELEMENT
Chromium (Cr) boasts a value of 8.5 on the Mohs scale,
which measures the hardness of minerals by their scratch
resistance to other materials. Lustrous and steely grey,
chromium has both a high melting point and corrosion
resistance. When added to iron in sufficient quantities,
it forms the corrosion-proof alloy known as stainless
steel. Chromium takes its name from the Greek word for
“colour” – trace amounts of the element are what make
rubies red. They are also
responsible for the brilliant
red hue of the samples of
crocoite mineral (shown
left), which were
retrieved from a
Tasmanian lead mine.DENSEST METAL
Discovered in 1803 by Smithson Tennant and William
Hyde Wollaston (both UK), osmium (Os) has a density of
22.59 g/cm^3 , about twice that of lead. The toxic nature
of osmium’s oxides mean that it is rarely used in its
natural form. However, its hard-wearing qualities
make it ideal for use in alloys for electrical contacts
and fountain-pen nibs. The least dense metal at
room temperature is lithium, at 0.5334 g/cm^3.Caesium is
so reactive that it
ignites on contact with
air. It is stored in glass
tubes inside inert gas,
or in a vacuum, to
keep it safe.