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Updated Mar 26, 2026
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Atomic Structure and Ionic Bonds
G
Gabriella
@gabsgabaga
1 / 5
Atomic Structure Basics
Ever wondered what makes gold different from oxygen? It's all about atomic structure and how particles are arranged. An element contains only one type of atom (like pure gold), whilst a compound has different types of atoms chemically stuck together (like water, H₂O).
Mixtures are completely different - they're just different substances mixed together without any chemical bonding happening. Think of it like a fruit salad where each piece of fruit keeps its own identity.
There's a handy naming trick for compounds: if there are only two elements, the name ends in 'ide' (like copper oxide). With three elements, it usually ends in 'ate' (like barium carbonate). The exception is compounds with 'OH' - these are always called hydroxides.
Quick Tip: Remember that protons and neutrons have roughly the same mass , but electrons are tiny - about 2000 times lighter!
Inside the Atom
The numbers on the periodic table tell you everything about an atom's structure. The mass number (big number) equals protons plus neutrons, whilst the atomic number (small number) tells you how many protons are there.
Here's the key relationship: number of electrons always equals number of protons in neutral atoms. To find neutrons, simply subtract the atomic number from the mass number.
Isotopes are atoms of the same element with different numbers of neutrons - like two versions of the same person wearing different shoes. Chlorine has isotopes with either 18 or 20 neutrons, but both still have 17 protons.
Electron shells work like energy levels around the nucleus. Electrons fill up the closest shell first (maximum 2), then the second shell (maximum 8), and so on. The number of outer electrons matches the group number on the periodic table, whilst the number of shells matches the period number.
Remember: Noble gases have full outer shells, which is why they're so unreactive - they're already 'happy'!
Chemical Bonding
Atoms bond together because they want full outer shells like the noble gases. There are two main types: ionic bonding and covalent bonding .
In ionic bonding, electrons transfer completely from metal to non-metal atoms. Metals lose electrons and become positive ions, whilst non-metals gain electrons and become negative ions. Think of sodium chloride: sodium gives up one electron to become Na⁺, and chlorine accepts it to become Cl⁻.
These oppositely charged ions attract each other through electrostatic forces, creating a giant lattice structure. This isn't just a few ions stuck together - it's a massive, regular pattern that continues in all directions throughout the entire crystal.
Scientific models help us visualise these complex structures in simpler ways, showing the key features without overwhelming detail.
Key Point: Metals always form positive ions, non-metals always form negative ions - opposites attract!
Properties of Ionic Compounds
Ionic compounds have distinctive properties that all stem from their giant lattice structure and the strong forces holding ions together. They have high melting points because you need loads of energy to break those strong electrostatic attractions between ions.
Water can dissolve many ionic compounds because the charged ions attract water molecules and form weak bonds with them. The ions basically get surrounded by water molecules and pulled away from the lattice.
Electrical conductivity depends on whether ions can move. In solid form, ionic compounds don't conduct electricity because ions are locked in fixed positions. However, when molten or dissolved, the ions become free to move and can carry electrical current between electrodes.
Ionic compounds are brittle - they shatter rather than bend. When you try to change their shape, you end up pushing ions with the same charge next to each other, and they repel strongly enough to break the structure apart.
Remember: Free-moving ions = electrical conduction. Fixed ions = no conduction.
Metallic Bonding and Properties
Metallic bonding creates a completely different structure called a giant metallic lattice. Picture positive metal ions surrounded by a 'sea' of delocalised electrons that are free to move throughout the entire structure.
These mobile electrons explain why metals are such good electrical and thermal conductors - the electrons can move freely and carry charge or energy. The strong metallic bonds also give metals high melting and boiling points.
Unlike ionic compounds, metals are malleable (can be hammered into shapes) and ductile (can be drawn into wires). This happens because layers of atoms can slide over each other whilst maintaining the metallic bonding - the electron sea just flows around the moving atoms.
Scientists use different models to represent these structures, from simple 'ball and stick' diagrams to more realistic 'space-filling' representations that show how tightly packed atoms really are.
Fun Fact: The same delocalised electrons that let metals conduct electricity also make them shiny - they reflect light really well!
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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
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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.
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
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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 Knowunity AI. 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 Knowunity AI. 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
Atomic Structure and Ionic Bonds
G
Gabriella
@gabsgabaga
Understanding atomic structure and chemical bonding is absolutely crucial for mastering GCSE chemistry. This topic covers everything from the basic building blocks of matter to how atoms stick together to form compounds - knowledge you'll use in every other chemistry... Show more
Atomic Structure Basics
Ever wondered what makes gold different from oxygen? It's all about atomic structure and how particles are arranged. An element contains only one type of atom (like pure gold), whilst a compound has different types of atoms chemically stuck together (like water, H₂O).
Mixtures are completely different - they're just different substances mixed together without any chemical bonding happening. Think of it like a fruit salad where each piece of fruit keeps its own identity.
There's a handy naming trick for compounds: if there are only two elements, the name ends in 'ide' (like copper oxide). With three elements, it usually ends in 'ate' (like barium carbonate). The exception is compounds with 'OH' - these are always called hydroxides.
Quick Tip: Remember that protons and neutrons have roughly the same mass , but electrons are tiny - about 2000 times lighter!
Sign up to see the contentIt's free!
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Inside the Atom
The numbers on the periodic table tell you everything about an atom's structure. The mass number (big number) equals protons plus neutrons, whilst the atomic number (small number) tells you how many protons are there.
Here's the key relationship: number of electrons always equals number of protons in neutral atoms. To find neutrons, simply subtract the atomic number from the mass number.
Isotopes are atoms of the same element with different numbers of neutrons - like two versions of the same person wearing different shoes. Chlorine has isotopes with either 18 or 20 neutrons, but both still have 17 protons.
Electron shells work like energy levels around the nucleus. Electrons fill up the closest shell first (maximum 2), then the second shell (maximum 8), and so on. The number of outer electrons matches the group number on the periodic table, whilst the number of shells matches the period number.
Remember: Noble gases have full outer shells, which is why they're so unreactive - they're already 'happy'!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Chemical Bonding
Atoms bond together because they want full outer shells like the noble gases. There are two main types: ionic bonding and covalent bonding .
In ionic bonding, electrons transfer completely from metal to non-metal atoms. Metals lose electrons and become positive ions, whilst non-metals gain electrons and become negative ions. Think of sodium chloride: sodium gives up one electron to become Na⁺, and chlorine accepts it to become Cl⁻.
These oppositely charged ions attract each other through electrostatic forces, creating a giant lattice structure. This isn't just a few ions stuck together - it's a massive, regular pattern that continues in all directions throughout the entire crystal.
Scientific models help us visualise these complex structures in simpler ways, showing the key features without overwhelming detail.
Key Point: Metals always form positive ions, non-metals always form negative ions - opposites attract!
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Properties of Ionic Compounds
Ionic compounds have distinctive properties that all stem from their giant lattice structure and the strong forces holding ions together. They have high melting points because you need loads of energy to break those strong electrostatic attractions between ions.
Water can dissolve many ionic compounds because the charged ions attract water molecules and form weak bonds with them. The ions basically get surrounded by water molecules and pulled away from the lattice.
Electrical conductivity depends on whether ions can move. In solid form, ionic compounds don't conduct electricity because ions are locked in fixed positions. However, when molten or dissolved, the ions become free to move and can carry electrical current between electrodes.
Ionic compounds are brittle - they shatter rather than bend. When you try to change their shape, you end up pushing ions with the same charge next to each other, and they repel strongly enough to break the structure apart.
Remember: Free-moving ions = electrical conduction. Fixed ions = no conduction.
Sign up to see the contentIt's free!
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Improve your grades
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Metallic Bonding and Properties
Metallic bonding creates a completely different structure called a giant metallic lattice. Picture positive metal ions surrounded by a 'sea' of delocalised electrons that are free to move throughout the entire structure.
These mobile electrons explain why metals are such good electrical and thermal conductors - the electrons can move freely and carry charge or energy. The strong metallic bonds also give metals high melting and boiling points.
Unlike ionic compounds, metals are malleable (can be hammered into shapes) and ductile (can be drawn into wires). This happens because layers of atoms can slide over each other whilst maintaining the metallic bonding - the electron sea just flows around the moving atoms.
Scientists use different models to represent these structures, from simple 'ball and stick' diagrams to more realistic 'space-filling' representations that show how tightly packed atoms really are.
Fun Fact: The same delocalised electrons that let metals conduct electricity also make them shiny - they reflect light really well!
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?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
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 Knowunity AI. 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 Knowunity AI. 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