The shape of liquids is variable
(they adopt the shape of the container) because, when the temperature
is above their melting point the particles cannot maintain the fixed
positions that they have when they are in a solid state and they
move in a disorderly fashion.
When not affected by gravity,
the natural form of liquids is a sphere (a drop). If an astronaut in a
space station orbiting the Earth spills a glass of water, the liquid
adopts the form of large drops suspended in the air.
The
volume of
liquids is practically invariable, because the particles, although not
forming a fixed structure as in the case of solids, remain relatively
near to each other as they do in the solid state.
Liquids
can flow, because their particles
have freedom of movement and are not in fixed positions so that they
can move into the spaces among them, allowing the movement of the whole
of the liquid mass.
A stream of liquid pours into
the bottle and adopts its shape as its particles are widely separated
and
can "flow". The particles in the ice cube cannot enter. Look at the
animated visual and click on "See molecular view" to understand what is
happening at that level.
