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24 Dec 2025
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Comprehensive AQA AS Chemistry: Bonding Notes
Emma Eddleston
@emmaeddleston_dyjj
1 / 4
Electron Shells and Bonding Basics
Think of electron shells as floors in a building - each one can hold a specific number of residents (electrons). Shell 1 holds just 2 electrons, shell 2 can fit 8, shell 3 holds 18, and shell 4 can accommodate 32. As you go higher up the building (higher shell numbers), the energy levels increase too.
Within each shell, you'll find different types of orbitals - think of these as individual rooms that can hold up to 2 electrons each. Every shell has an s-orbital, shells 2 and above have p-orbitals (3 of them), shells 3+ have d-orbitals (5 of them), and shells 4+ have f-orbitals (7 of them).
When filling orbitals, electrons are like people choosing seats on a bus - they'll sit alone first before sharing. They fill up singly before pairing, and paired electrons must spin in opposite directions. The filling order follows a specific pattern: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p.
Quick Tip: Remember that electrons are lazy - they always fill the lowest energy orbitals first!
Ionic and Covalent Bonding
Ionic bonds form when metals give electrons to non-metals, creating a powerful electrostatic attraction between positive and negative ions. Group 1 metals lose 1 electron , Group 2 lose 2 electrons , whilst Group 6 non-metals gain 2 electrons and Group 7 gain 1 electron .
Ionic compounds form giant ionic lattices where each ion is surrounded by oppositely charged neighbours. This gives them high melting points, makes them soluble in water, and means they conduct electricity when molten or dissolved (but not as solids).
Covalent bonding happens between non-metals that share electrons rather than transferring them. A single covalent bond represents one shared pair of electrons, shown as a line between atoms . Double and triple bonds involve sharing 2 or 3 pairs of electrons respectively.
Co-ordinate bonds are special covalent bonds where both electrons come from just one atom - the donor atom gives a lone pair to an electron-deficient acceptor. Despite their different formation, they're just as strong as regular covalent bonds.
Remember: Metals give, non-metals take (ionic), but non-metals share with each other (covalent)!
Polarity and Intermolecular Forces
Electronegativity measures how greedily an atom pulls electron density towards itself in a covalent bond. It increases across periods and decreases down groups, with fluorine being the most electronegative at 4.0 on the Pauling scale.
When atoms with different electronegativities bond, you get polar bonds with partial charges . However, a molecule can have polar bonds but still be non-polar overall if the electron cloud is evenly distributed across the whole structure.
Intermolecular forces are the weak attractions between molecules that determine physical properties. Van der Waals forces exist between all molecules and get stronger with molecular size - this is why larger molecules have higher boiling points. Branched molecules have weaker forces than straight chains due to less surface contact.
Permanent dipole-dipole forces occur between polar molecules, whilst hydrogen bonding is the strongest intermolecular force, forming when hydrogen bonds to oxygen, nitrogen, or fluorine.
Key Insight: Intermolecular forces are much weaker than actual bonds, but they control whether something is a solid, liquid, or gas at room temperature!
Molecular Shapes and Material Structures
Molecular shapes depend on electron pair repulsion - electrons push apart to get as far from each other as possible. Lone pairs repel more strongly than bonding pairs, affecting the final shape. You can represent 3D structures using solid lines (in the plane), solid wedges (coming out), and dotted wedges (going in).
Different structure types explain material properties. Giant ionic structures have high melting points and conduct when molten. Simple covalent structures have low melting points due to weak intermolecular forces. Giant covalent structures like diamond and graphite have very high melting points.
Diamond is incredibly hard because every carbon atom bonds to four others in a rigid 3D network, making it perfect for cutting tools. Graphite has layers that slide over each other (making it soft and useful for pencils) plus delocalised electrons that conduct electricity (ideal for electrodes).
The arrangement and movement of particles differs dramatically between solids (regular, vibrating), liquids (random, jostling), and gases (random, rapid movement), explaining their different properties like compressibility and diffusion rates.
Amazing Fact: Diamond and graphite are both pure carbon - their completely different properties come entirely from how the atoms are arranged and bonded!
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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
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This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
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Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
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Best app on earth! no words because it’s too good
Thomas R
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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
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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
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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
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.
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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
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
Comprehensive AQA AS Chemistry: Bonding Notes
Emma Eddleston
@emmaeddleston_dyjj
Chemical bonding is the foundation of how atoms stick together to form everything around you - from the water you drink to the diamond in a ring. Understanding how electrons behave in shells and orbitals, and how different types of... Show more
Electron Shells and Bonding Basics
Think of electron shells as floors in a building - each one can hold a specific number of residents (electrons). Shell 1 holds just 2 electrons, shell 2 can fit 8, shell 3 holds 18, and shell 4 can accommodate 32. As you go higher up the building (higher shell numbers), the energy levels increase too.
Within each shell, you'll find different types of orbitals - think of these as individual rooms that can hold up to 2 electrons each. Every shell has an s-orbital, shells 2 and above have p-orbitals (3 of them), shells 3+ have d-orbitals (5 of them), and shells 4+ have f-orbitals (7 of them).
When filling orbitals, electrons are like people choosing seats on a bus - they'll sit alone first before sharing. They fill up singly before pairing, and paired electrons must spin in opposite directions. The filling order follows a specific pattern: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p.
Quick Tip: Remember that electrons are lazy - they always fill the lowest energy orbitals first!
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Ionic and Covalent Bonding
Ionic bonds form when metals give electrons to non-metals, creating a powerful electrostatic attraction between positive and negative ions. Group 1 metals lose 1 electron , Group 2 lose 2 electrons , whilst Group 6 non-metals gain 2 electrons and Group 7 gain 1 electron .
Ionic compounds form giant ionic lattices where each ion is surrounded by oppositely charged neighbours. This gives them high melting points, makes them soluble in water, and means they conduct electricity when molten or dissolved (but not as solids).
Covalent bonding happens between non-metals that share electrons rather than transferring them. A single covalent bond represents one shared pair of electrons, shown as a line between atoms . Double and triple bonds involve sharing 2 or 3 pairs of electrons respectively.
Co-ordinate bonds are special covalent bonds where both electrons come from just one atom - the donor atom gives a lone pair to an electron-deficient acceptor. Despite their different formation, they're just as strong as regular covalent bonds.
Remember: Metals give, non-metals take (ionic), but non-metals share with each other (covalent)!
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Polarity and Intermolecular Forces
Electronegativity measures how greedily an atom pulls electron density towards itself in a covalent bond. It increases across periods and decreases down groups, with fluorine being the most electronegative at 4.0 on the Pauling scale.
When atoms with different electronegativities bond, you get polar bonds with partial charges . However, a molecule can have polar bonds but still be non-polar overall if the electron cloud is evenly distributed across the whole structure.
Intermolecular forces are the weak attractions between molecules that determine physical properties. Van der Waals forces exist between all molecules and get stronger with molecular size - this is why larger molecules have higher boiling points. Branched molecules have weaker forces than straight chains due to less surface contact.
Permanent dipole-dipole forces occur between polar molecules, whilst hydrogen bonding is the strongest intermolecular force, forming when hydrogen bonds to oxygen, nitrogen, or fluorine.
Key Insight: Intermolecular forces are much weaker than actual bonds, but they control whether something is a solid, liquid, or gas at room temperature!
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Molecular Shapes and Material Structures
Molecular shapes depend on electron pair repulsion - electrons push apart to get as far from each other as possible. Lone pairs repel more strongly than bonding pairs, affecting the final shape. You can represent 3D structures using solid lines (in the plane), solid wedges (coming out), and dotted wedges (going in).
Different structure types explain material properties. Giant ionic structures have high melting points and conduct when molten. Simple covalent structures have low melting points due to weak intermolecular forces. Giant covalent structures like diamond and graphite have very high melting points.
Diamond is incredibly hard because every carbon atom bonds to four others in a rigid 3D network, making it perfect for cutting tools. Graphite has layers that slide over each other (making it soft and useful for pencils) plus delocalised electrons that conduct electricity (ideal for electrodes).
The arrangement and movement of particles differs dramatically between solids (regular, vibrating), liquids (random, jostling), and gases (random, rapid movement), explaining their different properties like compressibility and diffusion rates.
Amazing Fact: Diamond and graphite are both pure carbon - their completely different properties come entirely from how the atoms are arranged and bonded!
We thought you’d never ask...
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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