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Erin
07/12/2025
Chemistry
GCSE Chemistry Unit 2
735
•
7 Dec 2025
•
GCSE Chemistry Unit 2: Bonding, Structure, and Properties Notes
Erin
@erin_agwa
1 / 4
Chemical Bonds and Metallic Bonding
You'll encounter three main types of chemical bonds depending on what elements are combining. Metallic bonding occurs between metals, ionic bonding happens between metals and non-metals, and covalent bonding forms between non-metals.
Metallic bonding creates a unique structure where positive metal ions arrange in regular rows. The magic happens because electrons can move freely throughout this structure, creating strong electrostatic forces that hold everything together. This is exactly why metals conduct electricity so well - those mobile electrons carry the charge!
Alloys are simply mixtures of different metals that are tougher than pure metals. When you mix metals with different-sized atoms, the layers become distorted, making it harder for them to slide past each other. This distortion is what makes alloys so much more durable than pure metals.
Quick Tip: Remember the bonding rules by thinking about the periodic table - metals on the left love to give away electrons, whilst non-metals on the right want to grab them!
Ionic and Covalent Bonding
Ionic bonding is all about electron transfer from metals to non-metals. Metals lose electrons and become positively charged, whilst non-metals gain those electrons and become negatively charged. Sometimes you need multiple atoms to balance the charges - just check the group numbers to work out how many electrons each element wants to lose or gain.
Ionic compounds form giant ionic lattices where positive and negative ions arrange in constant ratios. These structures have strong electrostatic forces acting in all directions, making them solid at room temperature. They can conduct electricity when molten or dissolved because the ions become free to move.
Covalent bonding works completely differently - atoms share pairs of electrons instead of transferring them. This creates much smaller molecules compared to the giant structures you see with ionic compounds.
Exam Focus: You need to know 8 specific small covalent molecules, so make sure you can draw and name them all!
Covalent Structures and Properties
Small covalent molecules are usually gases or liquids with low melting and boiling points. They only have weak intermolecular forces between molecules, though larger molecules do have slightly higher melting points. These molecules can't conduct electricity because they don't carry an overall electric charge.
Polymers are essentially very long chains made from repeating units called monomers. Strong covalent bonds hold the chain together, but weaker intermolecular forces exist between different chains. This combination makes them solid at room temperature.
Giant covalent structures contain thousands of atoms held together by strong covalent bonds throughout the entire structure. Diamond is a perfect example - each carbon atom makes four covalent bonds, creating an incredibly strong and hard material. However, all electrons are locked in bonds, so diamond can't conduct electricity.
Memory Trick: Think of polymers like a chain - strong links (covalent bonds) but the chains can still move past each other!
Carbon Allotropes and Quantitative Chemistry
Graphite has a completely different structure from diamond - each carbon atom only makes three bonds, leaving delocalised electrons free to move. This creates layers of hexagons that can slide over each other, making graphite soft and able to conduct electricity. Graphene is simply a single layer of graphite that still conducts electricity.
Fullerenes are fascinating carbon nanoparticles, with Buckminsterfullerene (C₆₀) containing exactly 60 carbon atoms. Silicon dioxide behaves similarly to diamond - each silicon joins to four oxygen atoms, creating high melting points but no electrical conductivity.
Moving into quantitative chemistry, the conservation of mass is fundamental - no atoms disappear or appear during reactions. The mass of products always equals the mass of reactants, which is why you must balance symbol equations. When gases are involved as reactants, reactions might appear to gain mass, but that's just because you're adding gas from the air.
Key Point: Whether it's bonding or chemical reactions, atoms are never created or destroyed - they just rearrange themselves!
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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.
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Sudenaz Ocak
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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
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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.
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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
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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
GCSE Chemistry Unit 2: Bonding, Structure, and Properties Notes
Erin
@erin_agwa
Understanding how atoms bond together is crucial for explaining why different materials behave so differently. From the conductivity of metals to the hardness of diamond, it all comes down to three main types of chemical bonding and how they create... Show more
Chemical Bonds and Metallic Bonding
You'll encounter three main types of chemical bonds depending on what elements are combining. Metallic bonding occurs between metals, ionic bonding happens between metals and non-metals, and covalent bonding forms between non-metals.
Metallic bonding creates a unique structure where positive metal ions arrange in regular rows. The magic happens because electrons can move freely throughout this structure, creating strong electrostatic forces that hold everything together. This is exactly why metals conduct electricity so well - those mobile electrons carry the charge!
Alloys are simply mixtures of different metals that are tougher than pure metals. When you mix metals with different-sized atoms, the layers become distorted, making it harder for them to slide past each other. This distortion is what makes alloys so much more durable than pure metals.
Quick Tip: Remember the bonding rules by thinking about the periodic table - metals on the left love to give away electrons, whilst non-metals on the right want to grab them!
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Ionic and Covalent Bonding
Ionic bonding is all about electron transfer from metals to non-metals. Metals lose electrons and become positively charged, whilst non-metals gain those electrons and become negatively charged. Sometimes you need multiple atoms to balance the charges - just check the group numbers to work out how many electrons each element wants to lose or gain.
Ionic compounds form giant ionic lattices where positive and negative ions arrange in constant ratios. These structures have strong electrostatic forces acting in all directions, making them solid at room temperature. They can conduct electricity when molten or dissolved because the ions become free to move.
Covalent bonding works completely differently - atoms share pairs of electrons instead of transferring them. This creates much smaller molecules compared to the giant structures you see with ionic compounds.
Exam Focus: You need to know 8 specific small covalent molecules, so make sure you can draw and name them all!
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Covalent Structures and Properties
Small covalent molecules are usually gases or liquids with low melting and boiling points. They only have weak intermolecular forces between molecules, though larger molecules do have slightly higher melting points. These molecules can't conduct electricity because they don't carry an overall electric charge.
Polymers are essentially very long chains made from repeating units called monomers. Strong covalent bonds hold the chain together, but weaker intermolecular forces exist between different chains. This combination makes them solid at room temperature.
Giant covalent structures contain thousands of atoms held together by strong covalent bonds throughout the entire structure. Diamond is a perfect example - each carbon atom makes four covalent bonds, creating an incredibly strong and hard material. However, all electrons are locked in bonds, so diamond can't conduct electricity.
Memory Trick: Think of polymers like a chain - strong links (covalent bonds) but the chains can still move past each other!
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Carbon Allotropes and Quantitative Chemistry
Graphite has a completely different structure from diamond - each carbon atom only makes three bonds, leaving delocalised electrons free to move. This creates layers of hexagons that can slide over each other, making graphite soft and able to conduct electricity. Graphene is simply a single layer of graphite that still conducts electricity.
Fullerenes are fascinating carbon nanoparticles, with Buckminsterfullerene (C₆₀) containing exactly 60 carbon atoms. Silicon dioxide behaves similarly to diamond - each silicon joins to four oxygen atoms, creating high melting points but no electrical conductivity.
Moving into quantitative chemistry, the conservation of mass is fundamental - no atoms disappear or appear during reactions. The mass of products always equals the mass of reactants, which is why you must balance symbol equations. When gases are involved as reactants, reactions might appear to gain mass, but that's just because you're adding gas from the air.
Key Point: Whether it's bonding or chemical reactions, atoms are never created or destroyed - they just rearrange themselves!
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?
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Is Knowunity really free of charge?
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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