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What did I learn? Scientific Knowledge Chemistry 1 (Particle Theory…
What did I learn? Scientific Knowledge Chemistry 1
Matter
What is matter?
The 'stuff' (substances) that everything is made of
From the table to the clothes we wear, it is all made up of matter
The air is even made up of matter - We just cannot see it!
There are 3 states that matter exist in
Solid
Liquid
Gas
How do we change between the different states? E.G. When Ice changes to water, from a solid to a liquid?
Solid to Liquid
Melting
E.G. An ice cube melts to turn into water
Liquid to Solid
Solidifying NOT Freezing
E.G. Molten lava solidifies into rock
Liquid to Gas
Evaporating NOT boiling
E.G. Water in a puddle evaporates back into the atmosphere
Gas to Liquid
Condensing
E.G When having a shower, mirrors becomes foggy because the warm water vapor in the air hits the cold mirror face.
What Surprised me? Vital things I had forgotten!
When a liquid turns to a solid, this is called solidifying and not freezing. This is because when thinking of freezing something, this has cold connotations, however, when a liquid turns to a solid this is not always cold! See the Lava example above, or when liquid candle wax cools and hardens.
This was a key learning moment for me and in the future when teaching this I will ensure to use the correct terminology (Solidifying) rather than freezing. I will also use examples such as the candle or lava to explain this to children.
We need to use the word Evaporating when describing a liquid changing to a gas NOT Boiling.
This is because liquids do not always boil in order to evaporate! For example, when a puddle evaporates from the ground, it does not boil, if you put your finger into the puddle it would not be at 100°C (Degrees Celsius).
Liquids have different temperatures at which they boil. The Boiling point of water = 100°C
After it goes beyond 100°C it begins to evaporate
Water Example
Solid Form - Ice Liquid form - Water Gas form - Steam
We think of steam as the mist coming out of a kettle - ITS NOT!
Steam is a clear gas that we cannot see! What we see here is the water molecules condensing back into the air.
What do the states look like in particle theory?
See Diagram
I used a diagram in Mind-map 1 (physics) to show the particle arrangements and I have learned that this is
incorrect
. There are not gaps between particles in liquids, they are still touching but just
DISORDERED
.
Properties of a Solid
Solids cannot flow freely
Solids cannot change shape without assistance
Solids cannot change volume
When you ask children what a solid is, they will usually say something hard E.G a chair, challenge their thoughts - What about a sponge or a T-shirt?
Solids do not have to be hard!
What about Salt?
When putting a pile of sugar on the table it moves. BUT, what about the individual pieces of sugar, they don't move or flow on their own, only when there are many together they can move!
These are also solids as cannot flow, change shape without assistance or volume.
Properties of a Liquid
When you ask children to think of a liquid they think of something with low Viscosity (measure of 'thickness') such as water or juice.
What about Syrup or Treacle? They can flow freely, change shape without assistance but cannot change volume and therefore, ARE a liquid.
Liquids can flow freely
Liquids can change shape without assistance
Liquids cannot change volume
Children struggle with the Conceptual Conservation of water. I.E Different sizes of containers containing the same volume of liquid, appear to have a different volume of liquid in them.
Challenge their thoughts, and allow children to measure a volume of liquid and transfer it into different containers and then back into the measuring jug at the end to see the volume hasn't changed!
Particle Theory
Particle theory explains how the particles arranged in different ways can make up the different states.
This can be confusing for younger children to understand - so focus on this with second level children.
Particles within a substance are CONSTANTLY moving/ Vibrating. Nothing is ever standing still despite appearing this way to the eye.
I have also learned that particles physically CANNOT stay still. In order for this to happen they have to reach absolute zero (−273.15°C).
This cannot happen because the substance would have to be surrounded by something that is colder than -273.15°C. This is impossible therefore, you cannot achieve a temperature of absolute zero.
Particles in
solids
are tightly packed together so cannot move, only vibrate. This is why solids cannot change shape or volume
Particles in
liquids
have no room between them, but are disordered meaning they can roll around and hence liquids can change shape.
Particles in
gasses
do not have to stay in contact and can move around, this is why gasses can change shape and volume easily.
This can be demonstrated by making the children act as the particles and try moving around as different states - being held tightly together for a solid etc...
Properties of a Gas
Gasses can flow freely
Gasses can change shape without assistance
Gasses can change volume
Children may find it more difficult to think of properties of a gas as they cannot be seen, however, this can be demonstrated easily with an air freshener. The gas flowing, changing shape and volume can be demonstrated throughout the classroom by having children standing at different points in the room and sitting down when they can eventually smell it.