Maths
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Responding to change (a2 only)
Infection and response
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Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
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1l the quest for political stability: germany, 1871-1991
Britain & the wider world: 1745 -1901
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
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Britain: 1509 -1745
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4 Dec 2025
•
Isabelle
@isabelle_study
Organic chemistry might seem overwhelming at first, but it's basically... Show more
Understanding displayed formulas is your first step into organic chemistry. These show every single atom and bond in a molecule - think of them as the detailed blueprint. Each carbon atom must have exactly four bonds, so you'll often need to add hydrogen atoms to complete the structure.
Skeletal formulas are the shorthand version that experienced chemists use. They only show the carbon skeleton and important functional groups, making complex molecules much easier to read. Don't worry if they look confusing now - you'll get used to them quickly.
The shape around each carbon in saturated hydrocarbons is always tetrahedral with bond angles of 109.5°. This 3D arrangement is crucial for understanding how molecules actually look in real life, not just on paper.
Quick Tip: Master the displayed formula first - once you can draw every atom and bond, skeletal formulas will make perfect sense!
Homologous series are families of compounds that share the same functional group. Each series has its own naming pattern - alkanes end in "-ane", alkenes end in "-ene", alcohols end in "-ol", and so on. Learning these patterns will save you loads of time in exams.
The key functional groups you need to know include alcohols , aldehydes , ketones , carboxylic acids , and esters (COO link). Each one gives the molecule completely different properties.
Naming rules follow a simple system: find the longest carbon chain first, then identify any branches, and finally add the appropriate prefixes and suffixes. It's like following a recipe - do it in the right order and you'll get the right name every time.
Remember: The functional group is like a molecule's personality - it determines how the compound will behave in reactions!
Structural isomers have the same molecular formula but completely different arrangements of atoms. Think of them as anagrams - same letters, different words. There are three main types: chain isomers (different carbon skeletons), position isomers (functional group in different positions), and functional group isomers (completely different functional groups).
Chain isomers like pentane and 2-methylbutane show how the same five carbons can be arranged in straight chains or branched structures. This seemingly small change can dramatically affect the compound's properties.
E-Z stereoisomers occur around double bonds where rotation is restricted. You need two different groups attached to each end of the double bond. In Z-isomers, the higher priority groups are on the same side, whilst in E-isomers, they're on opposite sides.
Key Insight: Isomers prove that structure matters just as much as composition - same ingredients, completely different properties!
E-Z isomers can have dramatically different physical properties, even though they contain exactly the same atoms. This difference comes down to molecular polarity and the resulting intermolecular forces.
Z-1,2-dichloroethene has a higher boiling point (60°C) because it's polar - the chlorine atoms are on the same side, creating an uneven distribution of charge. This allows for stronger permanent dipole-dipole attractions between molecules.
E-1,2-dichloroethene boils at just 48°C because it's non-polar - the chlorine atoms are on opposite sides, so their effects cancel out. With only van der Waals forces holding the molecules together, less energy is needed to separate them.
Real-world Application: This principle explains why some apparently identical compounds can have completely different melting points, boiling points, and solubilities!
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.
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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
Isabelle
@isabelle_study
Organic chemistry might seem overwhelming at first, but it's basically just understanding how carbon atoms link together to form different compounds. Once you grasp the patterns of how these molecules are structured and named, you'll find it's much more logical... Show more
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Understanding displayed formulas is your first step into organic chemistry. These show every single atom and bond in a molecule - think of them as the detailed blueprint. Each carbon atom must have exactly four bonds, so you'll often need to add hydrogen atoms to complete the structure.
Skeletal formulas are the shorthand version that experienced chemists use. They only show the carbon skeleton and important functional groups, making complex molecules much easier to read. Don't worry if they look confusing now - you'll get used to them quickly.
The shape around each carbon in saturated hydrocarbons is always tetrahedral with bond angles of 109.5°. This 3D arrangement is crucial for understanding how molecules actually look in real life, not just on paper.
Quick Tip: Master the displayed formula first - once you can draw every atom and bond, skeletal formulas will make perfect sense!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Homologous series are families of compounds that share the same functional group. Each series has its own naming pattern - alkanes end in "-ane", alkenes end in "-ene", alcohols end in "-ol", and so on. Learning these patterns will save you loads of time in exams.
The key functional groups you need to know include alcohols , aldehydes , ketones , carboxylic acids , and esters (COO link). Each one gives the molecule completely different properties.
Naming rules follow a simple system: find the longest carbon chain first, then identify any branches, and finally add the appropriate prefixes and suffixes. It's like following a recipe - do it in the right order and you'll get the right name every time.
Remember: The functional group is like a molecule's personality - it determines how the compound will behave in reactions!
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Structural isomers have the same molecular formula but completely different arrangements of atoms. Think of them as anagrams - same letters, different words. There are three main types: chain isomers (different carbon skeletons), position isomers (functional group in different positions), and functional group isomers (completely different functional groups).
Chain isomers like pentane and 2-methylbutane show how the same five carbons can be arranged in straight chains or branched structures. This seemingly small change can dramatically affect the compound's properties.
E-Z stereoisomers occur around double bonds where rotation is restricted. You need two different groups attached to each end of the double bond. In Z-isomers, the higher priority groups are on the same side, whilst in E-isomers, they're on opposite sides.
Key Insight: Isomers prove that structure matters just as much as composition - same ingredients, completely different properties!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
E-Z isomers can have dramatically different physical properties, even though they contain exactly the same atoms. This difference comes down to molecular polarity and the resulting intermolecular forces.
Z-1,2-dichloroethene has a higher boiling point (60°C) because it's polar - the chlorine atoms are on the same side, creating an uneven distribution of charge. This allows for stronger permanent dipole-dipole attractions between molecules.
E-1,2-dichloroethene boils at just 48°C because it's non-polar - the chlorine atoms are on opposite sides, so their effects cancel out. With only van der Waals forces holding the molecules together, less energy is needed to separate them.
Real-world Application: This principle explains why some apparently identical compounds can have completely different melting points, boiling points, and solubilities!
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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Explore the chemistry of amino acids, amides, and chirality in this detailed summary. Understand the formation of esters, the concept of optical isomers, and the role of amino acids in acid-base reactions. This resource covers key concepts such as isomerism, making salts, and the unique properties of chiral molecules, making it essential for organic chemistry studies.
ChemistryExplore the fundamentals of hydrocarbons, including their classification into aliphatic, alicyclic, and aromatic types. This summary covers key concepts such as homologous series, functional groups, and the general formulas for alkanes, alkenes, and alkynes. Ideal for OCR A A-Level Chemistry students seeking a concise understanding of organic chemistry.
ChemistryExplore key concepts in organic chemistry, including nomenclature, reaction mechanisms, and isomerism. This summary covers IUPAC naming rules, functional groups, and stereochemistry, providing a comprehensive overview for AQA AS Organic Chemistry students.
ChemistryExplore the structural characteristics and bonding of benzene, including the comparison between the Kekulé and delocalized models. This summary covers key concepts such as resonance, sigma bonds, and the implications of enthalpy changes in hydrogenation. Ideal for OCR A-Level Chemistry students seeking to understand the stability and reactivity of benzene and its derivatives.
ChemistryHope this helps!
ChemistryExplore the key concepts of hydrocarbons in National 5 Chemistry, including alkanes, alkenes, cycloalkanes, and isomerism. This summary covers the structural differences, properties, and general formulas of these compounds, providing a clear understanding of their roles in organic chemistry.
ChemistryApp 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
