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Responding to change (a2 only)
Infection and response
Homeostasis and response
Energy transfers (a2 only)
Cell biology
Organisms respond to changes in their internal and external environments (a-level only)
Biological molecules
Organisation
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Britain & the wider world: 1745 -1901
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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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3
0
Holly Hutchison
11/12/2025
Chemistry
Nat 5 chemistry unit 2
77
•
11 Dec 2025
•
Holly Hutchison
@hollyhutchison
Chemistry becomes much clearer when you understand that molecules are... Show more











This isn't just another boring list - it's your roadmap to chemistry success! Each tick box represents a skill that'll boost your confidence in exams.
Hydrocarbons form the foundation of organic chemistry. You'll need to master naming them, drawing their structures, and understanding why they behave differently. The checklist covers everything from simple alkanes (like methane) to more complex branched molecules.
Pro tip: Don't just memorise - understand the patterns. Once you spot how homologous series work, naming becomes much easier. The self-evaluation boxes help you identify exactly where to focus your revision time.
Remember: Confidence comes from practice, not perfection. Start with what you know and build from there!

Hydrocarbons are surprisingly simple - they're just hydrogen and carbon atoms joined together, but they don't mix with water at all. Think of oil and water separating!
A homologous series is like a chemical family where all members share similar properties and follow the same general formula pattern. It's like how all smartphones have similar features but different sizes.
The naming system uses prefixes that tell you exactly how many carbon atoms are present: meth (1), eth (2), prop (3), but (4), pent (5), hex (6), hept (7), and oct (8). Master these prefixes and you're halfway there!
Structural formulas show you exactly how atoms connect - carbon always makes 4 bonds whilst hydrogen only makes 1. Molecular formulas simply count how many atoms you've got.
Quick tip: The prefixes are the same across all hydrocarbon families - learn them once, use them everywhere!

Alkanes are the most straightforward hydrocarbons you'll encounter. Their general formula CₙH₂ₙ₊₂ might look scary, but it just means "for every n carbon atoms, you get 2n+2 hydrogen atoms."
These molecules are saturated, meaning they're packed full with hydrogen atoms and only have single bonds between carbons. When you test them with bromine water, absolutely nothing happens - the yellow colour stays put.
Alkanes are brilliant fuels because they burn easily and release loads of energy. From methane (CH₄) in your gas cooker to octane (C₈H₁₈) in petrol, they power our world.
The structural drawings might seem complex, but remember that carbon sits in the middle making 4 bonds, whilst hydrogen atoms dangle off the edges making just 1 bond each.
Memory trick: Saturated = satisfied = full of hydrogen atoms and can't take any more!

Alkenes are where chemistry gets exciting! Their general formula CₙH₂ₙ means they have fewer hydrogen atoms than alkanes, leaving room for a double bond between carbon atoms.
This unsaturated nature makes them incredibly reactive. Drop some bromine water on an alkene and watch it change from yellow to colourless instantly - it's like a chemical magic trick that proves the double bond exists.
Alkenes are the building blocks of plastics. That double bond can break open and link with other molecules, creating long chains that become everything from carrier bags to phone cases.
Starting with ethene (C₂H₄) and moving up to octene (C₈H₁₆), each alkene has that characteristic C=C double bond that makes it special. The structural formulas show this clearly with the double line between carbons.
Key insight: The double bond is both alkenes' strength (making plastics) and their weakness (making them reactive)!

Cycloalkanes are fascinating because they're saturated like alkanes but have the same general formula as alkenes (CₜH₂ₙ). The secret? Their carbon atoms form rings instead of straight chains.
These ring structures are completely saturated with single bonds throughout, so bromine water stays yellow when you test them - just like regular alkanes. The "cyclo" prefix immediately tells you you're dealing with a ring structure.
From the tiny triangle of cyclopropane (C₃H₆) to the larger cyclooctane (C₈H₁₆), these molecules show how the same atoms can arrange themselves in completely different ways.
The structural formulas look like geometric shapes - triangles, squares, pentagons - with hydrogen atoms attached to each corner where the carbon atoms sit.
Visual tip: Think of cycloalkanes as alkanes that have joined hands in a circle - same bonds, different shape!

Systematic naming sounds complicated but it's actually a brilliant system that tells you exactly what a molecule looks like just from its name. It's like having a chemical GPS coordinate!
For branched alkanes, you find the longest carbon chain first, then number from the end closest to any branches. Those little side chains get names based on their length: methyl (1 carbon), ethyl (2 carbons), propyl (3 carbons).
When there are multiple identical branches, you use prefixes like "di" or "tri" to show how many. The final name combines the position number, branch name, and main chain name all together.
Branched alkenes follow similar rules, but you number from the end closest to the double bond instead. The position of that double bond gets included in the final name because it's crucial information.
Success strategy: Break it down step by step - longest chain, number the carbons, identify branches, then put it all together!




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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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
Holly Hutchison
@hollyhutchison
Chemistry becomes much clearer when you understand that molecules are basically like different families, each with their own special characteristics. This summary covers the key hydrocarbons you'll need to master for your National 5 Chemistry exam - think of it... Show more

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This isn't just another boring list - it's your roadmap to chemistry success! Each tick box represents a skill that'll boost your confidence in exams.
Hydrocarbons form the foundation of organic chemistry. You'll need to master naming them, drawing their structures, and understanding why they behave differently. The checklist covers everything from simple alkanes (like methane) to more complex branched molecules.
Pro tip: Don't just memorise - understand the patterns. Once you spot how homologous series work, naming becomes much easier. The self-evaluation boxes help you identify exactly where to focus your revision time.
Remember: Confidence comes from practice, not perfection. Start with what you know and build from there!

Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Hydrocarbons are surprisingly simple - they're just hydrogen and carbon atoms joined together, but they don't mix with water at all. Think of oil and water separating!
A homologous series is like a chemical family where all members share similar properties and follow the same general formula pattern. It's like how all smartphones have similar features but different sizes.
The naming system uses prefixes that tell you exactly how many carbon atoms are present: meth (1), eth (2), prop (3), but (4), pent (5), hex (6), hept (7), and oct (8). Master these prefixes and you're halfway there!
Structural formulas show you exactly how atoms connect - carbon always makes 4 bonds whilst hydrogen only makes 1. Molecular formulas simply count how many atoms you've got.
Quick tip: The prefixes are the same across all hydrocarbon families - learn them once, use them everywhere!

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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Alkanes are the most straightforward hydrocarbons you'll encounter. Their general formula CₙH₂ₙ₊₂ might look scary, but it just means "for every n carbon atoms, you get 2n+2 hydrogen atoms."
These molecules are saturated, meaning they're packed full with hydrogen atoms and only have single bonds between carbons. When you test them with bromine water, absolutely nothing happens - the yellow colour stays put.
Alkanes are brilliant fuels because they burn easily and release loads of energy. From methane (CH₄) in your gas cooker to octane (C₈H₁₈) in petrol, they power our world.
The structural drawings might seem complex, but remember that carbon sits in the middle making 4 bonds, whilst hydrogen atoms dangle off the edges making just 1 bond each.
Memory trick: Saturated = satisfied = full of hydrogen atoms and can't take any more!

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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Alkenes are where chemistry gets exciting! Their general formula CₙH₂ₙ means they have fewer hydrogen atoms than alkanes, leaving room for a double bond between carbon atoms.
This unsaturated nature makes them incredibly reactive. Drop some bromine water on an alkene and watch it change from yellow to colourless instantly - it's like a chemical magic trick that proves the double bond exists.
Alkenes are the building blocks of plastics. That double bond can break open and link with other molecules, creating long chains that become everything from carrier bags to phone cases.
Starting with ethene (C₂H₄) and moving up to octene (C₈H₁₆), each alkene has that characteristic C=C double bond that makes it special. The structural formulas show this clearly with the double line between carbons.
Key insight: The double bond is both alkenes' strength (making plastics) and their weakness (making them reactive)!

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Cycloalkanes are fascinating because they're saturated like alkanes but have the same general formula as alkenes (CₜH₂ₙ). The secret? Their carbon atoms form rings instead of straight chains.
These ring structures are completely saturated with single bonds throughout, so bromine water stays yellow when you test them - just like regular alkanes. The "cyclo" prefix immediately tells you you're dealing with a ring structure.
From the tiny triangle of cyclopropane (C₃H₆) to the larger cyclooctane (C₈H₁₆), these molecules show how the same atoms can arrange themselves in completely different ways.
The structural formulas look like geometric shapes - triangles, squares, pentagons - with hydrogen atoms attached to each corner where the carbon atoms sit.
Visual tip: Think of cycloalkanes as alkanes that have joined hands in a circle - same bonds, different shape!

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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Systematic naming sounds complicated but it's actually a brilliant system that tells you exactly what a molecule looks like just from its name. It's like having a chemical GPS coordinate!
For branched alkanes, you find the longest carbon chain first, then number from the end closest to any branches. Those little side chains get names based on their length: methyl (1 carbon), ethyl (2 carbons), propyl (3 carbons).
When there are multiple identical branches, you use prefixes like "di" or "tri" to show how many. The final name combines the position number, branch name, and main chain name all together.
Branched alkenes follow similar rules, but you number from the end closest to the double bond instead. The position of that double bond gets included in the final name because it's crucial information.
Success strategy: Break it down step by step - longest chain, number the carbons, identify branches, then put it all together!

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Access to all documents
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Access to all documents
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By signing up you accept Terms of Service and Privacy Policy

Access to all documents
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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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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