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5
0
G
Gracie B
05/12/2025
Chemistry
Chemistry paper 1 aqa
384
•
5 Dec 2025
•
AQA Chemistry Paper 1 - Comprehensive Guide
G
Gracie B
@gracieb_l513o
1 / 5
Elements, Compounds and Atomic Structure
Everything you see is made from just 100 different elements - pure substances containing only one type of atom. When different elements join together chemically, they form compounds with completely new properties.
The periodic table organises all elements by their atomic number (number of protons). Mendeleev originally arranged elements by atomic weight but left gaps for undiscovered elements - pretty clever prediction! Elements in the same group (column) behave similarly because they have the same number of electrons in their outer shell.
Our understanding of atoms evolved dramatically over time. Dalton thought atoms were solid spheres, but Rutherford's famous gold foil experiment revealed that atoms are mostly empty space with a tiny, dense nucleus. Bohr then showed that electrons orbit at specific energy levels, whilst Chadwick discovered neutrons.
Key Tip: Remember that atomic number = number of protons, and isotopes are atoms of the same element with different numbers of neutrons.
Group 1 alkali metals become more reactive as you go down, whilst Group 7 halogens become less reactive. Noble gases (Group 0) are unreactive because they have full outer electron shells. Transition metals are found between groups 2 and 3, and they're stronger, denser, and make great catalysts.
Chemical Bonding and Structure
There are three main types of bonding that hold atoms together, and understanding these explains why materials have such different properties. Ionic bonding occurs between metals and non-metals, where electrons transfer completely to form oppositely charged ions.
Covalent bonding happens when non-metals share electrons to achieve stable electron arrangements. These can form small molecules (like water) or giant structures like diamond and graphite. Diamond has four covalent bonds per carbon atom, making it incredibly hard, whilst graphite's layered structure with delocalised electrons makes it slippery and conductive.
Metallic bonding involves a "sea" of delocalised electrons that can move freely around metal atoms. This explains why metals conduct electricity and can be shaped without breaking.
Remember: Ionic compounds conduct electricity when molten or dissolved because the charged ions can move freely.
Polymers are long chains made from repeating units called monomers. Fullerenes like Buckminsterfullerene (C₆₀) are cage-like carbon structures that have exciting applications in nanotechnology. Nanoparticles have huge surface areas relative to their volume, making them excellent catalysts.
Small molecules have low melting points because the forces between molecules are weak, even though the covalent bonds within molecules are strong.
Calculations and Chemical Quantities
Chemical calculations might look scary, but they're just about counting atoms and molecules using a unit called the mole. One mole contains the same number of particles as there are atoms in 12g of carbon-12 - that's Avogadro's constant (6.02 × 10²³).
The relative formula mass (Mr) is simply the sum of all atomic masses in a compound's formula. You can calculate percentage mass of any element in a compound, which is useful for working out what's actually in your substances.
Mole equations help you predict how much product you'll get from reactions. The key relationship is: moles = mass ÷ Mr. You can also calculate gas volumes and concentrations using similar principles.
Pro Tip: In reactions, the limiting reactant determines how much product you can make - just like running out of bread limits how many sandwiches you can make!
Atom economy tells you how much of your starting materials ends up in useful products rather than waste. High atom economy means more sustainable chemistry. Percentage yield compares what you actually get with the theoretical maximum - real reactions rarely give 100% yield due to practical limitations.
Understanding conservation of mass is crucial - atoms aren't created or destroyed in chemical reactions, just rearranged.
Energy Changes and Electrochemistry
Chemical reactions either release energy (exothermic) or absorb energy (endothermic) from their surroundings. Exothermic reactions like combustion and oxidation make the surroundings warmer, whilst endothermic reactions like thermal decomposition cool things down.
Energy diagrams show that breaking bonds requires energy input, whilst forming new bonds releases energy. The overall energy change depends on the balance between these processes. Activation energy is the minimum energy needed to start any reaction.
Electrochemical cells convert chemical energy directly into electrical energy using two different electrodes. Fuel cells are particularly important for clean energy - they react hydrogen with oxygen to produce electricity and water, with no harmful emissions.
Real-world connection: Your phone battery uses electrochemical reactions to store and release energy on demand.
Bond energies help predict whether reactions will be exothermic or endothermic. If more energy is released when forming new bonds than is needed to break old ones, the reaction is exothermic. Fuel cells represent the future of clean transport, as they only produce water as a waste product.
The beauty of these systems is that they directly convert chemical potential energy into useful electrical energy without the inefficiencies of burning fuels.
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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
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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
AQA Chemistry Paper 1 - Comprehensive Guide
G
Gracie B
@gracieb_l513o
Chemistry might seem overwhelming at first, but it's basically about understanding how the tiniest building blocks of everything around you work together. From the atoms in your phone to the reactions happening when you cook dinner, these fundamental concepts explain... Show more
Elements, Compounds and Atomic Structure
Everything you see is made from just 100 different elements - pure substances containing only one type of atom. When different elements join together chemically, they form compounds with completely new properties.
The periodic table organises all elements by their atomic number (number of protons). Mendeleev originally arranged elements by atomic weight but left gaps for undiscovered elements - pretty clever prediction! Elements in the same group (column) behave similarly because they have the same number of electrons in their outer shell.
Our understanding of atoms evolved dramatically over time. Dalton thought atoms were solid spheres, but Rutherford's famous gold foil experiment revealed that atoms are mostly empty space with a tiny, dense nucleus. Bohr then showed that electrons orbit at specific energy levels, whilst Chadwick discovered neutrons.
Key Tip: Remember that atomic number = number of protons, and isotopes are atoms of the same element with different numbers of neutrons.
Group 1 alkali metals become more reactive as you go down, whilst Group 7 halogens become less reactive. Noble gases (Group 0) are unreactive because they have full outer electron shells. Transition metals are found between groups 2 and 3, and they're stronger, denser, and make great catalysts.
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Chemical Bonding and Structure
There are three main types of bonding that hold atoms together, and understanding these explains why materials have such different properties. Ionic bonding occurs between metals and non-metals, where electrons transfer completely to form oppositely charged ions.
Covalent bonding happens when non-metals share electrons to achieve stable electron arrangements. These can form small molecules (like water) or giant structures like diamond and graphite. Diamond has four covalent bonds per carbon atom, making it incredibly hard, whilst graphite's layered structure with delocalised electrons makes it slippery and conductive.
Metallic bonding involves a "sea" of delocalised electrons that can move freely around metal atoms. This explains why metals conduct electricity and can be shaped without breaking.
Remember: Ionic compounds conduct electricity when molten or dissolved because the charged ions can move freely.
Polymers are long chains made from repeating units called monomers. Fullerenes like Buckminsterfullerene (C₆₀) are cage-like carbon structures that have exciting applications in nanotechnology. Nanoparticles have huge surface areas relative to their volume, making them excellent catalysts.
Small molecules have low melting points because the forces between molecules are weak, even though the covalent bonds within molecules are strong.
Sign up to see the contentIt's free!
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Calculations and Chemical Quantities
Chemical calculations might look scary, but they're just about counting atoms and molecules using a unit called the mole. One mole contains the same number of particles as there are atoms in 12g of carbon-12 - that's Avogadro's constant (6.02 × 10²³).
The relative formula mass (Mr) is simply the sum of all atomic masses in a compound's formula. You can calculate percentage mass of any element in a compound, which is useful for working out what's actually in your substances.
Mole equations help you predict how much product you'll get from reactions. The key relationship is: moles = mass ÷ Mr. You can also calculate gas volumes and concentrations using similar principles.
Pro Tip: In reactions, the limiting reactant determines how much product you can make - just like running out of bread limits how many sandwiches you can make!
Atom economy tells you how much of your starting materials ends up in useful products rather than waste. High atom economy means more sustainable chemistry. Percentage yield compares what you actually get with the theoretical maximum - real reactions rarely give 100% yield due to practical limitations.
Understanding conservation of mass is crucial - atoms aren't created or destroyed in chemical reactions, just rearranged.
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By signing up you accept Terms of Service and Privacy Policy
Energy Changes and Electrochemistry
Chemical reactions either release energy (exothermic) or absorb energy (endothermic) from their surroundings. Exothermic reactions like combustion and oxidation make the surroundings warmer, whilst endothermic reactions like thermal decomposition cool things down.
Energy diagrams show that breaking bonds requires energy input, whilst forming new bonds releases energy. The overall energy change depends on the balance between these processes. Activation energy is the minimum energy needed to start any reaction.
Electrochemical cells convert chemical energy directly into electrical energy using two different electrodes. Fuel cells are particularly important for clean energy - they react hydrogen with oxygen to produce electricity and water, with no harmful emissions.
Real-world connection: Your phone battery uses electrochemical reactions to store and release energy on demand.
Bond energies help predict whether reactions will be exothermic or endothermic. If more energy is released when forming new bonds than is needed to break old ones, the reaction is exothermic. Fuel cells represent the future of clean transport, as they only produce water as a waste product.
The beauty of these systems is that they directly convert chemical potential energy into useful electrical energy without the inefficiencies of burning fuels.
Sign up to see the contentIt's free!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
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.
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Most popular content in Chemistry
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English - inspector calls quotes and analysis
Quotes from every main character
English Literature10
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