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Temperature and States
Another way in which states of matter can be described is by noting the types of motion that particles undergo. To help you understand the types of motion that are allowed in the different states imagine a crowded area.
Imagine that the area is so crowded that you can't move from one place to another. You still may be able to wiggle a bit, but it is so crowded that you can't even turn in place. In chemistry terminology, we would say that you are capable of vibrational motion, but not rotational (turning in place) or translational (moving from one spot on the ground to another).
Run the model and carefully observe what happens. Notice how the molecules of H2O (*) in this model move relative to the others.
(* Note that this is a 2 dimensional model and thus
cannot show the correct intermolecular bonding structure.)
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Which of the following would you conclude about the H<sub>2</sub>O
molecules in this model?
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<html>They are not capable of either vibrational motion or rotational motion.
They are capable of vibrational motion, but not rotational motion.
They are capable of both vibrational and rotational motion.
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<b>Was your first guess to this question right or wrong? If you guessed
wrong initially, make sure you take a closer look at the model while it's
running. Although there is some slight tilting of molecules back and forth
(especially on the surface), there is no rotational motion. That is,
individual molecules are not free to turn 360 degrees. Only vibrational
motion is happening. </b>
<p>
<b>Also, molecules are not moving freely from one place to another. In
other words, there is no <i>translational motion</i>.</b>
</p>
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What state are the H<sub>2</sub>O molecules in?
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Solid
Liquid
Gas
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<b>If you are still confused by the previous 2 questions, you may be
mistakenly thinking that solids have no motion on the molecular level.
This is not true. The only time <i>all</i> motion would cease, in theory,
is at 0 degrees Kelvin. Also known as absolute zero, this temperature has
never been obtained in the laboratory. </b>
<p>
<b>We can summarize these findings by noting that solids are capable of
vibrational motion, but not rotational nor translational.</b>
</p>
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