The seemingly simple process of phase changes-those transitions between states of matter-is more complex than previously known, NYU Chemistry Professor Mark Tuckerman and his colleagues have found. Their study reveals the need to rethink one of science’s building blocks and, with it, how some of the basic principles underlying the behavior of matter are taught in our classrooms.
classes are just not right.”
heat energy or temperature which the matter may possess at a given time.
could not immediately escape because they would still be bouncing about among their neighbors, but the field of each particle would now be repelling all of its neighbors, and the mass would expand rapidly. The particles on the outside of the mass would move outward indefinitely, leaving the next layer free to escape and so on. Matter in this condition is known as ‘gas.’
instance, can be described as matter whose particle velocities are so close to that of escape that the additional force applied by a gravitational field such as that of the earth is sufficient to cause the particles to escape, or ‘flow’ in the direction of the force applied by the field. If such matter were removed from the influence of exterior fields, and released in space, it would immediately assume the shape of a sphere, which shape it would retain indefinitely so long as no exterior force were brought to bear. It would,
therefore have the characteristics of a very soft solid.
demonstrating that its particles do have velocities above those necessary for escape. Actually, even though we do not remove the air, molecules of the water will constantly be escaping from the surface in spite of the downward bombardment of the air molecules, and the glass would eventually become empty. This, much slower process of escape by the mingling of the molecules of a liquid with the molecules of a surrounding gas is known as evaporation.