27. Liquid Metals
and a Gaseous (?) Metal
All the metals are solids, harder or softer. Such is the general rule. But there are
exceptions.
Some metals are more like liquids. A chip of gallium or cesium melts on your palm,
because the melting point of these metals is just below thirty degrees Celsius (86°F).
Francium, which has not been prepared as the pure metal so far, would melt at room
temperature.
Mercury is a classical example of a liquid metal which everybody knows. It freezes at
minus 39°C (-38.2°F), which makes it eligible for various kinds of thermometers.
An important rival to mercury in this respect is gallium, and here is why. Mercury boils
at the comparatively low temperature of about 300°C (572°F). This makes mercury
thermometers useless for measuring high temperatures. But it takes a temperature of
2000°C (3670°F) to turn gallium into a vapour.
Not a single metal can remain in the liquid state for so long, i.e., has such a large
interval between its melting and boiling points, as gallium. This makes gallium an
excellent material for high-temperature thermometers.
One more thing, and this is quite remarkable. Scientists have proved theoretically that if
there existed a heavy analogue of mercury (an element with a very large atomic number
an inhabitant of, the imaginary seventh floor - eighth period - of the Big House, unknown
on Earth) its natural state at ordinary conditions would be gaseous.
A gas possessing the chemical properties of a metal!
Will scientists ever have such a unique element to study?