Well, first off all water is H2O
and it is a
compound, not an element. There are 92 naturally
occurring elements, and compounds are made by
H2O does indeed occur abundantly
in all three states today, near and at the earth
surface, so it is special in that sense.
But in more general terms virtually all
materials, elements and compounds can occur in
any of the basic three states!
For example, consider table salt NaCL. At
room conditions the stable entity is halite
NaCl; it is a cubic crystal. Take a magnifying
glass and get a few grains of salt from the
table salt shaker and you will see beautiful
Now at room pressure, if you heat the halite
up to about 800 deg Celsius, it will melt, then
you will have liquid NaCl, and if you then heat
the liquid up to about 1465 deg Celsius it will
boil. That is, it will go to the gas or vapor
This means that just like H2O,
NaCl can exist as a solid, liquid or gas, it
depends on the temperature.
There is a special point called the triple
point where all three states of matter coexist.
For water this JUST HAPPENS to be near the
conditions at the earth surface, roughly 1 bar
(pressure), and 25 deg Celsius (temperature).
This is why we see all three states of water on
earth. Water vapor condenses to form liquid
water droplets in clouds or freezes to form snow
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