Science Master Special – States of Matter (a role play)

This is a role play which I think can give you younger learner some ideas about the connections between solids liquids and gases. Try it with some friends.

There are only two roles: (1) The Director (2) The actors or water particles (molecules).

What is needed:  (1) Space to act out the role play (2) Temperature prompts for the Director [-15oC, -10oC, 0oC, 10oC, 30oC, 50oC, 80oC, 100oC]

To start the temperature is -15oC. The water particles are stationary (frozen) connected to each other by bonds (Hydrogen bonds-see below). The actors depict this by holding hands with the the other actors.

At -10oC the crystalline bonding is still holding BUT the molecules are slowly vibrating but still remaining in the same place.

As the temperature approaches 0oC things start to happen. The water molecules begin to move, slowly. The actors are not holding hands but have some contact with each other. The hydrogen bonding is still there.They can move from one molecule to another but must never lose contact …moving slowly. They are now liquid water molecules.

The temperature slowly increases and as it increases the water molecules are getting more and more energy from the heat source and begin to move faster. They are moving faster BUT still in contact with other water molecules. At 30oC one or two of the water molecules break away and then come back again.

At 50oC one water molecule escapes completely and doesn’t return. The rest are moving even faster.

At 80oC several molecules break away and maybe one returns. At 100oC the whole group begins to break up and move into the room they are now water vapour molecules and not connected at all to each other.

Hydrogen Bonds

The water molecule is an interesting particle. It consist of a central Oxygen atom and two Hydrogen atoms connected to it. The structure gives the Oxygen atom a small negative electrical charge, the Hydrogen atoms have a small positive charge. This means that the Hydrogen atom of one molecule of water can be attracted to the negatively charged Oxygen atom of another water molecule. This is your Hydrogen Bond.

Mara (11) asked a question about elements and why they exist in different states at room temperature.

Mara’s question was “Why is it that some elements are Gases or Solids at room temperature? I can understand why we would need them to be different, and my first guess would be that the density of the element is the answer, but I don’t know how that would work. So I wonder how is that some elements are different at room temperature, and why aren’t they all solids or all gases?”

Mara, many thanks for an interesting question. I asked my friends about this and your ideas.

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Some thoughts. I am thinking about the individual ‘atoms’ that make up the structure of an element. For Hydrogen you have two atoms joined by a bond, and the attraction between each Hydrogen molecule (the name given to bonded hydrogen structure) is very small. For the element Carbon you have a complex structure of bonding atoms each carbon atom being bonded to four other carbon atoms (it has one of the highest melting points). For the metals you have a fairly loose bond between the atoms BUT some of the atoms are very ‘heavy’ and as melting any element means giving it energy and making the atoms move apart … the more energy you have to supply… the higher the melting point. (see my little story on a previous post).

So like you suggested in your question it is a complex situation, with lots of different factors affecting the temperature at which an element melts and maybe density is part of that…. (revised 24/07/16). You can ‘Leave a Reply’ or ask another question if you want further thoughts.