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Maths
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Responding to change (a2 only)
Infection and response
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Energy transfers (a2 only)
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Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
Organisation
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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
4 Dec 2025
309
10 pages
sarah thomas @sarahthxmas
Understanding matter and electricity might seem tricky at first, but it's actually quite straightforward once you grasp the... Show more
Every atom is like a tiny solar system with three main players, each with their own charge and mass properties.
Protons live in the nucleus (centre) and carry a positive charge (+1) with a mass of 1. Neutrons are their neutral neighbours in the nucleus - no charge (0) but the same mass as protons. Electrons are the lightweight champions that whizz around the nucleus in shells. They're negatively charged (-1) but have virtually no mass (0).
The atomic number tells you how many protons and electrons an atom has - they're always equal in a neutral atom. The mass number is the total of protons plus neutrons. For example, sodium (Na) has an atomic number of 11 and a mass number of 23.
Understanding atomic structure helps explain why elements behave differently and how they bond together to form compounds.
Memory Hack Think PEN - Protons are Positive, Electrons are nEgative, Neutrons are Neutral!
Ever wonder why ice melts into water and then turns into steam? It's all about how particles behave in different states of matter.
In solids, particles are packed closely together in neat, organised rows. They barely move at all - just vibrate slightly in their fixed positions. Think of soldiers standing at attention in perfect formation.
Liquids are where things get more interesting. The particles are still close together, but they're not arranged in any particular pattern. They can slide around each other freely, which is why you can pour water but not a brick.
Gases are the rebels of the particle world. These particles are spread far apart and zoom around quickly in all directions. There's no organisation whatsoever - complete chaos, but in a good way!
Quick Tip Remember the particle spacing with this trick - solids are like a crowded lift, liquids like a busy dance floor, and gases like people scattered across a football pitch.
The periodic table is basically split into two main teams metals and non-metals, and they couldn't be more different in personality.
Metals are the reliable, practical types. They're excellent conductors of both heat and electricity, which makes them perfect for things like saucepans and electrical wires. They're also dense, strong, and have that characteristic shiny appearance that catches the light.
Non-metals are quite the opposite - they're more brittle, dull-looking, and terrible at conducting electricity or heat. However, they can be highly reactive in chemical reactions, making them essential for many biological processes.
This fundamental difference in properties determines how we use different elements in everyday life, from the copper in your phone charger to the carbon in your pencil.
Real-World Connection Next time you're in the kitchen, notice how metal pans heat up quickly (good conductor) while plastic handles stay cool (poor conductor)!
Electric circuits are like the circulatory system of the electrical world, and understanding them is crucial for your physics exams.
In a series circuit, the current flows through each component one after another, like cars following a single-lane road. The key rule here is that current stays the same at every point in the circuit - if it's 2A at one point, it's 2A everywhere.
Potential difference (voltage) is essentially the electrical "push" that moves charges around the circuit. It's defined as the work done per unit charge, measured in volts. The formula is V = W/Q, where W is work done in joules and Q is charge in coulombs.
Think of potential difference like water pressure in pipes - the higher the pressure, the stronger the flow.
Exam Tip Series circuits are your friend for calculations because the current never changes - just remember that voltages add up across different components!
These electrical formulas might look intimidating, but they're actually your best friends for solving circuit problems.
Power measures how quickly energy is transferred, calculated as energy transferred divided by time. It tells you how much work an electrical device can do per second. Efficiency compares useful output to total input - basically, how good a device is at not wasting energy.
Current is fundamentally the rate at which charge flows past a point, given by I = ΔQ/Δt. Imagine counting how many coulombs of charge pass by in each second - that's your current in amperes.
These relationships help explain everything from why your phone battery drains faster when using power-hungry apps to how energy companies calculate your electricity bill.
Study Smart Practice with these formulas using real examples - calculate the current in your phone charger or the efficiency of LED bulbs compared to old incandescent ones!
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
App 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
sarah thomas
@sarahthxmas
Understanding matter and electricity might seem tricky at first, but it's actually quite straightforward once you grasp the basics. This study guide covers three key areas: how particles behave in different states of matter, the structure of atoms, and how... Show more
Access to all documents
Improve your grades
Join milions of students
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Every atom is like a tiny solar system with three main players, each with their own charge and mass properties.
Protons live in the nucleus (centre) and carry a positive charge (+1) with a mass of 1. Neutrons are their neutral neighbours in the nucleus - no charge (0) but the same mass as protons. Electrons are the lightweight champions that whizz around the nucleus in shells. They're negatively charged (-1) but have virtually no mass (0).
The atomic number tells you how many protons and electrons an atom has - they're always equal in a neutral atom. The mass number is the total of protons plus neutrons. For example, sodium (Na) has an atomic number of 11 and a mass number of 23.
Understanding atomic structure helps explain why elements behave differently and how they bond together to form compounds.
Memory Hack: Think PEN - Protons are Positive, Electrons are nEgative, Neutrons are Neutral!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Ever wonder why ice melts into water and then turns into steam? It's all about how particles behave in different states of matter.
In solids, particles are packed closely together in neat, organised rows. They barely move at all - just vibrate slightly in their fixed positions. Think of soldiers standing at attention in perfect formation.
Liquids are where things get more interesting. The particles are still close together, but they're not arranged in any particular pattern. They can slide around each other freely, which is why you can pour water but not a brick.
Gases are the rebels of the particle world. These particles are spread far apart and zoom around quickly in all directions. There's no organisation whatsoever - complete chaos, but in a good way!
Quick Tip: Remember the particle spacing with this trick - solids are like a crowded lift, liquids like a busy dance floor, and gases like people scattered across a football pitch.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The periodic table is basically split into two main teams: metals and non-metals, and they couldn't be more different in personality.
Metals are the reliable, practical types. They're excellent conductors of both heat and electricity, which makes them perfect for things like saucepans and electrical wires. They're also dense, strong, and have that characteristic shiny appearance that catches the light.
Non-metals are quite the opposite - they're more brittle, dull-looking, and terrible at conducting electricity or heat. However, they can be highly reactive in chemical reactions, making them essential for many biological processes.
This fundamental difference in properties determines how we use different elements in everyday life, from the copper in your phone charger to the carbon in your pencil.
Real-World Connection: Next time you're in the kitchen, notice how metal pans heat up quickly (good conductor) while plastic handles stay cool (poor conductor)!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Electric circuits are like the circulatory system of the electrical world, and understanding them is crucial for your physics exams.
In a series circuit, the current flows through each component one after another, like cars following a single-lane road. The key rule here is that current stays the same at every point in the circuit - if it's 2A at one point, it's 2A everywhere.
Potential difference (voltage) is essentially the electrical "push" that moves charges around the circuit. It's defined as the work done per unit charge, measured in volts. The formula is V = W/Q, where W is work done in joules and Q is charge in coulombs.
Think of potential difference like water pressure in pipes - the higher the pressure, the stronger the flow.
Exam Tip: Series circuits are your friend for calculations because the current never changes - just remember that voltages add up across different components!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
These electrical formulas might look intimidating, but they're actually your best friends for solving circuit problems.
Power measures how quickly energy is transferred, calculated as energy transferred divided by time. It tells you how much work an electrical device can do per second. Efficiency compares useful output to total input - basically, how good a device is at not wasting energy.
Current is fundamentally the rate at which charge flows past a point, given by I = ΔQ/Δt. Imagine counting how many coulombs of charge pass by in each second - that's your current in amperes.
These relationships help explain everything from why your phone battery drains faster when using power-hungry apps to how energy companies calculate your electricity bill.
Study Smart: Practice with these formulas using real examples - calculate the current in your phone charger or the efficiency of LED bulbs compared to old incandescent ones!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
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
App 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
Combined Science
Sociology