States of matter is all about how particles behave differently... Show more
SociologySign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
91
•
3 Dec 2025
•
GCSE States of Matter: Key Facts and Concepts
Victoria Cicha
@victoriacicha_yhfa
1 / 3
States of Matter and Particle Theory
Ever wonder why ice melts or water boils? It's all about particles and energy! All matter is made of tiny particles (atoms, molecules or ions) that behave differently depending on temperature.
In solids, particles are tightly packed in a lattice arrangement with strong forces of attraction between them. They don't move from their positions but vibrate in place. The hotter the solid gets, the more they vibrate until eventually they overcome these forces and melt into a liquid.
Particles in liquids have moderate forces of attraction and can move past each other freely, which is why liquids flow and take the shape of their container (while maintaining their volume). They move randomly, and adding heat makes them move faster, causing slight expansion.
💡 Think of solids as people holding hands in a crowd (stuck in place), liquids as people moving through a crowded shop (free to move but still close), and gases as people in a massive field (moving freely in any direction).
When energy is added or removed, substances change state - melting (solid → liquid), freezing (liquid → solid), vaporisation (liquid → gas), and condensation (gas → liquid).
Gases and Changes of State
Gases are fascinating! The particles have virtually no forces of attraction between them and move freely in all directions. They travel in straight lines and only interact when they collide with each other or container walls.
Unlike solids and liquids, gases have neither fixed shape nor volume - they expand to fill any container completely. When gas particles bounce off container walls, they create pressure. The hotter a gas gets, the faster the particles move, increasing either the volume (if allowed to expand) or the pressure (in a fixed container).
The particle theory helps explain all these properties, but it's not perfect. It doesn't show the actual size of particles or the space between them, nor does it fully illustrate the strength of forces between particles.
🔍 Did you know? The spaces between gas particles are much larger than in liquids or solids - that's why gases can be compressed so easily!
It's important to understand that changing state (melting, freezing, etc.) involves physical changes where no new substances are formed - the original substance just changes form. These changes are relatively easy to reverse by adding or removing energy.
Physical vs Chemical Changes
When substances change states (solid to liquid to gas), they undergo physical changes. The key thing to remember is that no new substances are created - it's still the same chemical, just in a different form. You can easily reverse these changes by adding or removing energy.
Chemical reactions are completely different! During a chemical reaction, the bonds between atoms actually break, and the atoms rearrange themselves to form entirely new substances. The starting chemicals (reactants) transform into different chemicals (products) with new properties.
Unlike physical changes, chemical changes are typically difficult to reverse. For example, burning paper creates ash and gases - you can't easily turn these back into paper!
⚡ Quick check: If you melt chocolate, that's a physical change (still chocolate, just melted). If you burn toast, that's a chemical change (you've created new substances with different properties).
Understanding the difference between physical and chemical changes helps you make sense of everyday phenomena and is crucial for your GCSE Chemistry success.
We thought you’d never ask...
What is the Knowunity AI companion?
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.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Most popular content: States of Matter
Most popular content in Chemistry
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
4.8/5
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
GCSE States of Matter: Key Facts and Concepts
Victoria Cicha
@victoriacicha_yhfa
States of matter is all about how particles behave differently in solids, liquids and gases. Understanding these differences helps explain how substances change from one state to another when energy is added or removed, and why materials have their characteristic... Show more
States of Matter and Particle Theory
Ever wonder why ice melts or water boils? It's all about particles and energy! All matter is made of tiny particles (atoms, molecules or ions) that behave differently depending on temperature.
In solids, particles are tightly packed in a lattice arrangement with strong forces of attraction between them. They don't move from their positions but vibrate in place. The hotter the solid gets, the more they vibrate until eventually they overcome these forces and melt into a liquid.
Particles in liquids have moderate forces of attraction and can move past each other freely, which is why liquids flow and take the shape of their container (while maintaining their volume). They move randomly, and adding heat makes them move faster, causing slight expansion.
💡 Think of solids as people holding hands in a crowd (stuck in place), liquids as people moving through a crowded shop (free to move but still close), and gases as people in a massive field (moving freely in any direction).
When energy is added or removed, substances change state - melting (solid → liquid), freezing (liquid → solid), vaporisation (liquid → gas), and condensation (gas → liquid).
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Gases and Changes of State
Gases are fascinating! The particles have virtually no forces of attraction between them and move freely in all directions. They travel in straight lines and only interact when they collide with each other or container walls.
Unlike solids and liquids, gases have neither fixed shape nor volume - they expand to fill any container completely. When gas particles bounce off container walls, they create pressure. The hotter a gas gets, the faster the particles move, increasing either the volume (if allowed to expand) or the pressure (in a fixed container).
The particle theory helps explain all these properties, but it's not perfect. It doesn't show the actual size of particles or the space between them, nor does it fully illustrate the strength of forces between particles.
🔍 Did you know? The spaces between gas particles are much larger than in liquids or solids - that's why gases can be compressed so easily!
It's important to understand that changing state (melting, freezing, etc.) involves physical changes where no new substances are formed - the original substance just changes form. These changes are relatively easy to reverse by adding or removing energy.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Physical vs Chemical Changes
When substances change states (solid to liquid to gas), they undergo physical changes. The key thing to remember is that no new substances are created - it's still the same chemical, just in a different form. You can easily reverse these changes by adding or removing energy.
Chemical reactions are completely different! During a chemical reaction, the bonds between atoms actually break, and the atoms rearrange themselves to form entirely new substances. The starting chemicals (reactants) transform into different chemicals (products) with new properties.
Unlike physical changes, chemical changes are typically difficult to reverse. For example, burning paper creates ash and gases - you can't easily turn these back into paper!
⚡ Quick check: If you melt chocolate, that's a physical change (still chocolate, just melted). If you burn toast, that's a chemical change (you've created new substances with different properties).
Understanding the difference between physical and chemical changes helps you make sense of everyday phenomena and is crucial for your GCSE Chemistry success.
We thought you’d never ask...
What is the Knowunity AI companion?
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.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
0
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Mock Exam
Quiz
Flashcards
Essay
Similar content
Understanding Waves: Light & Sound
Explore the fundamental concepts of waves, including electromagnetic and sound waves, their properties, and behaviors. This summary covers key topics such as wave types (transverse and longitudinal), the electromagnetic spectrum, and the relationship between waves and energy. Ideal for Year 9 students studying physics.
Chemistry7
Chemistry: Bonding & Structure
Explore the key concepts of bonding and structure in chemistry, including ionic, covalent, and metallic bonding, as well as the properties of giant covalent structures and nanoparticles. This summary covers essential topics for GCSE students, focusing on particle theory, intermolecular forces, and the unique characteristics of various molecular structures. Ideal for active recall and exam preparation.
Chemistry9
Atomic Model Evolution
Explore the evolution of atomic models from John Dalton's solid spheres to Rutherford's nuclear atom and Bohr's electron shells. This summary highlights key experiments and theories that shaped our understanding of atomic structure, making it essential for students studying chemistry and physics.
Chemistry9
States of Matter Overview
Explore the fundamental concepts of particles and the three states of matter: solids, liquids, and gases. This summary covers the arrangement and movement of particles, the kinetic molecular theory, and phase changes. Ideal for Year 7 students preparing for exams.
Chemistry7
Evolution of Atomic Theory
Explore the key milestones in the evolution of atomic theory, from Democritus's indivisible atoms to Bohr's electron shell model. This summary covers the contributions of Dalton, Thompson, Rutherford, and Bohr, detailing the progression of ideas about atomic structure and the nature of matter. Ideal for students studying chemistry and physics.
Chemistry8
Chemical Bonding Explained
Explore the fundamentals of chemical bonding, including ionic, covalent, and metallic structures. This summary covers the properties of solids, liquids, and gases, the formation of compounds, and the significance of giant covalent structures and nanoparticles. Ideal for AQA GCSE Chemistry Higher students seeking to understand the intricacies of molecular interactions and material properties.
Chemistry9
Most popular content: States of Matter
Most popular content in Chemistry
Most popular content
Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
4.8/5
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