Maths
Chemistry
Biology
English Language
History
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
Substance exchange
Bioenergetics
Genetic information & variation
Inheritance, variation and evolution
Genetics & ecosystems (a2 only)
Ecology
Cells
Show all topics
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
Chemistry
10 Dec 2025
210
4 pages
aamnah j @aamnahj
Chemical bonding shapes everything around you - from the salt on your chips to the diamond in jewellery.... Show more
Ever wondered why salt dissolves in water but doesn't conduct electricity until it's melted? Ionic bonding happens when metals give away electrons to non-metals, creating oppositely charged particles that attract each other.
Take sodium chloride - sodium loses an electron to become Na⁺, whilst chlorine gains one to become Cl⁻. These oppositely charged ions stick together through strong electrostatic forces, forming a giant lattice structure that's hard with high melting points.
Here's the key bit for your exams ionic compounds only conduct electricity when molten or dissolved because the ions need to be free to move and carry the charge.
Quick Tip Remember metals lose electrons (become positive), non-metals gain electrons (become negative) - opposites attract!
Covalent bonding occurs when non-metals share electrons, but the results can be dramatically different depending on the structure formed.
Diamond showcases the ultimate covalent structure - each carbon forms four strong bonds in a rigid 3D network. This makes it incredibly hard with high melting points, but it can't conduct electricity because all electrons are locked in bonds.
Graphite tells a different story. Each carbon bonds to only three others, leaving the fourth electron delocalised. These free electrons make graphite conduct electricity, whilst weak forces between layers make it slippery - perfect for pencil lead and lubricants.
Graphene, essentially one layer of graphite, conducts electricity even better and has exciting applications in electronics and composites.
Exam Focus Diamond = hard, doesn't conduct. Graphite = soft layers, conducts electricity due to delocalised electrons.
Small covalent molecules like water have low melting points because weak forces exist between molecules, not within them. Breaking these intermolecular forces requires little energy, explaining why water boils at just 100°C.
Polymers are long chains of repeating units with strong covalent bonds within the chain and significant forces between chains. When writing molecular formulas, put the repeating unit in brackets with 'n' outside, like (C₂H₄)ₙ.
Fullerenes are fascinating carbon structures with hollow centres and hexagonal rings. Buckminsterfullerene (C₆₀) was the first discovered, whilst carbon nanotubes are cylindrical versions with incredible strength-to-weight ratios.
These materials revolutionise technology - from drug delivery systems to computer chips, their unique structures create extraordinary properties.
Memory Trick Think of polymers as molecular chains - strong links (covalent bonds) but the chains can still move past each other.
Metallic bonding creates a "sea of electrons" - positive metal ions surrounded by delocalised electrons that can move freely. This explains why metals conduct electricity and heat so well, plus why they're malleable rather than brittle.
Metal alloys mix different metals to create stronger materials. Different-sized atoms disrupt the regular arrangement, preventing layers from sliding over each other easily - that's why steel is harder than pure iron.
Nanoparticles have massive surface area to volume ratios, making them incredibly useful. They're revolutionising everything from medicine to electronics because their tiny size gives them unique properties.
Applications include drug delivery, computer chips, antibacterial deodorants, and surgical masks - their high surface area makes them excellent catalysts too.
Key Concept Size matters! As particles get smaller, their surface area to volume ratio increases dramatically, creating new properties and applications.
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.
6
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Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
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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
aamnah j
@aamnahj
Chemical bonding shapes everything around you - from the salt on your chips to the diamond in jewellery. Understanding how atoms stick together helps explain why materials behave so differently, whether they conduct electricity, and how strong they are.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Ever wondered why salt dissolves in water but doesn't conduct electricity until it's melted? Ionic bonding happens when metals give away electrons to non-metals, creating oppositely charged particles that attract each other.
Take sodium chloride - sodium loses an electron to become Na⁺, whilst chlorine gains one to become Cl⁻. These oppositely charged ions stick together through strong electrostatic forces, forming a giant lattice structure that's hard with high melting points.
Here's the key bit for your exams: ionic compounds only conduct electricity when molten or dissolved because the ions need to be free to move and carry the charge.
Quick Tip: Remember metals lose electrons (become positive), non-metals gain electrons (become negative) - opposites attract!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Covalent bonding occurs when non-metals share electrons, but the results can be dramatically different depending on the structure formed.
Diamond showcases the ultimate covalent structure - each carbon forms four strong bonds in a rigid 3D network. This makes it incredibly hard with high melting points, but it can't conduct electricity because all electrons are locked in bonds.
Graphite tells a different story. Each carbon bonds to only three others, leaving the fourth electron delocalised. These free electrons make graphite conduct electricity, whilst weak forces between layers make it slippery - perfect for pencil lead and lubricants.
Graphene, essentially one layer of graphite, conducts electricity even better and has exciting applications in electronics and composites.
Exam Focus: Diamond = hard, doesn't conduct. Graphite = soft layers, conducts electricity due to delocalised electrons.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Small covalent molecules like water have low melting points because weak forces exist between molecules, not within them. Breaking these intermolecular forces requires little energy, explaining why water boils at just 100°C.
Polymers are long chains of repeating units with strong covalent bonds within the chain and significant forces between chains. When writing molecular formulas, put the repeating unit in brackets with 'n' outside, like (C₂H₄)ₙ.
Fullerenes are fascinating carbon structures with hollow centres and hexagonal rings. Buckminsterfullerene (C₆₀) was the first discovered, whilst carbon nanotubes are cylindrical versions with incredible strength-to-weight ratios.
These materials revolutionise technology - from drug delivery systems to computer chips, their unique structures create extraordinary properties.
Memory Trick: Think of polymers as molecular chains - strong links (covalent bonds) but the chains can still move past each other.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Metallic bonding creates a "sea of electrons" - positive metal ions surrounded by delocalised electrons that can move freely. This explains why metals conduct electricity and heat so well, plus why they're malleable rather than brittle.
Metal alloys mix different metals to create stronger materials. Different-sized atoms disrupt the regular arrangement, preventing layers from sliding over each other easily - that's why steel is harder than pure iron.
Nanoparticles have massive surface area to volume ratios, making them incredibly useful. They're revolutionising everything from medicine to electronics because their tiny size gives them unique properties.
Applications include drug delivery, computer chips, antibacterial deodorants, and surgical masks - their high surface area makes them excellent catalysts too.
Key Concept: Size matters! As particles get smaller, their surface area to volume ratio increases dramatically, creating new properties and applications.
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.
6
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
Sociology