Subjects
Maths
Chemistry
Biology
English Language
History
Responding to change (a2 only)
Infection and response
Homeostasis and response
Energy transfers (a2 only)
Cell biology
Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
Organisation
Substance exchange
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
Cells
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Britain & the wider world: 1745 -1901
1l the quest for political stability: germany, 1871-1991
The cold war
Inter-war germany
Medieval period: 1066 -1509
2d religious conflict and the church in england, c1529-c1570
2o democracy and nazism: germany, 1918-1945
1f industrialisation and the people: britain, c1783-1885
1c the tudors: england, 1485-1603
2m wars and welfare: britain in transition, 1906-1957
World war two & the holocaust
2n revolution and dictatorship: russia, 1917-1953
2s the making of modern britain, 1951-2007
World war one
Britain: 1509 -1745
Show all topics
Physics
12 Dec 2025
340
6 pages
Jessica Plane @essicalane_jeu6oyvga
Understanding how particles behave in different states of matter is crucial for grasping many physics and chemistry concepts.... Show more
The particle model is your key to understanding how matter behaves in different states. It's a simple but powerful way to visualise what's happening inside solids, liquids, and gases at the microscopic level.
Think of everything around you as being made of tiny particles that are constantly moving. The way these particles are arranged and how much they move determines whether something is solid, liquid, or gas.
Quick Tip Remember that particles are always moving - even in ice, they're vibrating on the spot!
Density tells us how much mass is packed into a given volume, and it varies dramatically between states. Solids have tightly packed particles in regular patterns with strong forces holding them together - think of soldiers standing in formation.
Liquids have particles that are still close but can slide past each other freely. The forces between particles are much weaker than in solids. Gases have particles zooming around with loads of space between them and very weak forces.
Changes of state are physical changes where the mass always stays the same. Whether you're melting chocolate or boiling water, you're not creating or destroying particles - just changing how they're arranged and how fast they move.
Remember Physical changes are reversible - you can always get back to where you started!
When you heat something, you're increasing its internal energy - the total energy stored by all the particles in the system. This energy boost can either make particles move faster (raising temperature) or help them break free from their current arrangement (changing state).
Heating graphs show something fascinating during melting and boiling, temperature stays constant even though you're still adding energy. This energy goes into breaking bonds between particles rather than making them move faster.
The opposite happens during cooling. When gas condenses or liquid freezes, particles form stronger bonds and release energy, but again temperature stays constant during these changes.
Key Insight Temperature staying constant during state changes doesn't mean energy isn't being transferred - it's just being used differently!
Specific heat capacity measures how much energy you need to warm up 1 kg of a substance by 1°C. Different materials need different amounts of energy - water needs quite a lot compared to metals, which is why radiators work so well.
Latent heat is the energy needed for state changes. Specific latent heat narrows this down to changing 1 kg of substance from one state to another without changing temperature.
There are two types you need to know specific latent heat of fusion (solid to liquid changes) and specific latent heat of vaporisation (liquid to gas changes). Vaporisation typically requires much more energy than fusion.
Memory Trick "Fusion" sounds like "freezing" - both are about solid-liquid changes!
Gas pressure happens because particles constantly bash into container walls, creating force. Higher temperature means particles have more kinetic energy and hit harder and more often, increasing pressure.
In a container that can change size (like a balloon), pressure differences matter. If outside pressure is higher, the gas gets compressed. If inside pressure is higher, the gas expands.
When you heat gas in a fixed container, particles speed up and collide more frequently with walls, so pressure increases. When you give gas more space at constant temperature, particles spread out and hit walls less often, so pressure drops.
Doing work on gases (like using a bike pump) transfers energy to the gas, increasing its internal energy and temperature. You're literally forcing more energetic particles into the space.
Real-world Connection This explains why bike tyres get warm when you pump them up!
A bike pump perfectly demonstrates these principles in action. When you push the handle down, you're doing work on the air, forcing particles into the tyre where they join the existing particles.
More particles in the same space means more collisions with the tyre walls, creating higher pressure. Since work done equals energy transferred, the internal energy of the gas increases, making it hotter.
The air inside ends up with higher pressure and temperature than before. However, the tyre will gradually lose heat to the cooler surroundings, which decreases the internal energy and slightly reduces the pressure over time.
This is why your bike tyres might feel slightly less firm on a cold morning - the lower temperature means lower internal energy and pressure.
Physics in Action Next time you pump up a bike tyre, feel how warm the pump gets - that's energy transfer in action!
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Jessica Plane
@essicalane_jeu6oyvga
Understanding how particles behave in different states of matter is crucial for grasping many physics and chemistry concepts. This topic covers everything from why ice melts to how your bike pump works, using the particle model to explain what's happening... Show more
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The particle model is your key to understanding how matter behaves in different states. It's a simple but powerful way to visualise what's happening inside solids, liquids, and gases at the microscopic level.
Think of everything around you as being made of tiny particles that are constantly moving. The way these particles are arranged and how much they move determines whether something is solid, liquid, or gas.
Quick Tip: Remember that particles are always moving - even in ice, they're vibrating on the spot!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Density tells us how much mass is packed into a given volume, and it varies dramatically between states. Solids have tightly packed particles in regular patterns with strong forces holding them together - think of soldiers standing in formation.
Liquids have particles that are still close but can slide past each other freely. The forces between particles are much weaker than in solids. Gases have particles zooming around with loads of space between them and very weak forces.
Changes of state are physical changes where the mass always stays the same. Whether you're melting chocolate or boiling water, you're not creating or destroying particles - just changing how they're arranged and how fast they move.
Remember: Physical changes are reversible - you can always get back to where you started!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
When you heat something, you're increasing its internal energy - the total energy stored by all the particles in the system. This energy boost can either make particles move faster (raising temperature) or help them break free from their current arrangement (changing state).
Heating graphs show something fascinating: during melting and boiling, temperature stays constant even though you're still adding energy. This energy goes into breaking bonds between particles rather than making them move faster.
The opposite happens during cooling. When gas condenses or liquid freezes, particles form stronger bonds and release energy, but again temperature stays constant during these changes.
Key Insight: Temperature staying constant during state changes doesn't mean energy isn't being transferred - it's just being used differently!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Specific heat capacity measures how much energy you need to warm up 1 kg of a substance by 1°C. Different materials need different amounts of energy - water needs quite a lot compared to metals, which is why radiators work so well.
Latent heat is the energy needed for state changes. Specific latent heat narrows this down to changing 1 kg of substance from one state to another without changing temperature.
There are two types you need to know: specific latent heat of fusion (solid to liquid changes) and specific latent heat of vaporisation (liquid to gas changes). Vaporisation typically requires much more energy than fusion.
Memory Trick: "Fusion" sounds like "freezing" - both are about solid-liquid changes!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Gas pressure happens because particles constantly bash into container walls, creating force. Higher temperature means particles have more kinetic energy and hit harder and more often, increasing pressure.
In a container that can change size (like a balloon), pressure differences matter. If outside pressure is higher, the gas gets compressed. If inside pressure is higher, the gas expands.
When you heat gas in a fixed container, particles speed up and collide more frequently with walls, so pressure increases. When you give gas more space at constant temperature, particles spread out and hit walls less often, so pressure drops.
Doing work on gases (like using a bike pump) transfers energy to the gas, increasing its internal energy and temperature. You're literally forcing more energetic particles into the space.
Real-world Connection: This explains why bike tyres get warm when you pump them up!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
A bike pump perfectly demonstrates these principles in action. When you push the handle down, you're doing work on the air, forcing particles into the tyre where they join the existing particles.
More particles in the same space means more collisions with the tyre walls, creating higher pressure. Since work done equals energy transferred, the internal energy of the gas increases, making it hotter.
The air inside ends up with higher pressure and temperature than before. However, the tyre will gradually lose heat to the cooler surroundings, which decreases the internal energy and slightly reduces the pressure over time.
This is why your bike tyres might feel slightly less firm on a cold morning - the lower temperature means lower internal energy and pressure.
Physics in Action: Next time you pump up a bike tyre, feel how warm the pump gets - that's energy transfer in action!
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
7
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Quotes from every main character
English LiteratureApp Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Sociology