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Aidan Devine
29/11/2025
Chemistry
AS Chemistry- Shapes of molecules and bond angles
138
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29 Nov 2025
•
Understanding AS Chemistry: Molecular Shapes and Bond Angles
A
Aidan Devine
@aidandevine_toov
1 / 3
Basic Molecular Shapes
When molecules form, their shape is determined by how electron pairs arrange themselves to minimize repulsion. With 2 bonding pairs around a central atom, the molecule adopts a linear shape with a perfect 180° bond angle, as seen in CO₂.
Molecules with 3 bonding pairs form a trigonal planar shape where all atoms lie in the same plane with 120° bond angles. A common example is BF₃, where the boron sits at the center with three fluorine atoms arranged evenly around it.
As we add another electron pair, 4 bonding pairs create a tetrahedral arrangement with bond angles of 109.5°. This is the classic shape of methane (CH₄), where the carbon atom sits at the center with hydrogen atoms at each corner of the tetrahedron.
More complex molecules with 5 bonding pairs form a trigonal bipyramidal shape with two different bond angles: 90° between axial and equatorial bonds, and 120° between equatorial bonds. PCl₅ is a textbook example of this arrangement.
⚡ Remember that these shapes occur when there are only bonding pairs present - the introduction of lone pairs will distort these ideal arrangements and angles!
Advanced Molecular Shapes
With 6 bonding pairs, molecules adopt an octahedral shape with all bond angles at 90°. Sulfur hexafluoride (SF₆) perfectly demonstrates this, with fluorine atoms at the corners of an octahedron around the central sulfur atom.
When lone pairs enter the picture, they change everything. A molecule with 3 bonding pairs and 1 lone pair (like ammonia, NH₃) forms a pyramidal shape with bond angles of 107° – slightly compressed from the ideal tetrahedral angle due to the lone pair's stronger repulsion.
Water (H₂O) is the classic example of a molecule with 2 bonding pairs and 2 lone pairs, creating a bent shape with a bond angle of 104.5°. The two lone pairs push against the bonding pairs, further decreasing the angle from the tetrahedral ideal.
More exotic molecules with 3 bonding pairs and 2 lone pairs form a T-shaped arrangement. Here, bond angles are less than 90° and less than 120° due to significant repulsion from the lone pairs. Chlorine trifluoride (ClF₃) displays this unusual geometry.
🔍 Lone pairs occupy more space than bonding pairs because they're only attracted to one nucleus, causing greater repulsion and distorting the expected bond angles.
Special Molecular Arrangements
Some molecules exhibit particularly distinctive shapes, such as those with 4 bonding pairs and 2 lone pairs. These molecules form a square planar arrangement with 90° bond angles between adjacent bonds. The lone pairs position themselves 180° apart to minimize repulsion.
In square planar molecules, all four bonding atoms lie in the same plane, creating a flat, square-shaped structure. This arrangement is commonly seen in coordination compounds like ²⁻, where the central platinum atom is surrounded by four chloride ions.
The square planar geometry is quite distinctive because the lone pairs occupy positions above and below the plane of the bonding atoms. This creates an area of high electron density perpendicular to the molecular plane, affecting how these molecules interact with other species.
💡 Square planar molecules often display interesting chemical properties and reactivity patterns due to their open coordination sites perpendicular to the molecular plane.
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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
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
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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
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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
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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
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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
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
Understanding AS Chemistry: Molecular Shapes and Bond Angles
A
Aidan Devine
@aidandevine_toov
Molecular shape and bond angles are critical in chemistry as they help us understand how molecules behave and interact. These characteristics are determined by the arrangement of electron pairs (both bonding and lone pairs) around the central atom, following the... Show more
Basic Molecular Shapes
When molecules form, their shape is determined by how electron pairs arrange themselves to minimize repulsion. With 2 bonding pairs around a central atom, the molecule adopts a linear shape with a perfect 180° bond angle, as seen in CO₂.
Molecules with 3 bonding pairs form a trigonal planar shape where all atoms lie in the same plane with 120° bond angles. A common example is BF₃, where the boron sits at the center with three fluorine atoms arranged evenly around it.
As we add another electron pair, 4 bonding pairs create a tetrahedral arrangement with bond angles of 109.5°. This is the classic shape of methane (CH₄), where the carbon atom sits at the center with hydrogen atoms at each corner of the tetrahedron.
More complex molecules with 5 bonding pairs form a trigonal bipyramidal shape with two different bond angles: 90° between axial and equatorial bonds, and 120° between equatorial bonds. PCl₅ is a textbook example of this arrangement.
⚡ Remember that these shapes occur when there are only bonding pairs present - the introduction of lone pairs will distort these ideal arrangements and angles!
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Advanced Molecular Shapes
With 6 bonding pairs, molecules adopt an octahedral shape with all bond angles at 90°. Sulfur hexafluoride (SF₆) perfectly demonstrates this, with fluorine atoms at the corners of an octahedron around the central sulfur atom.
When lone pairs enter the picture, they change everything. A molecule with 3 bonding pairs and 1 lone pair (like ammonia, NH₃) forms a pyramidal shape with bond angles of 107° – slightly compressed from the ideal tetrahedral angle due to the lone pair's stronger repulsion.
Water (H₂O) is the classic example of a molecule with 2 bonding pairs and 2 lone pairs, creating a bent shape with a bond angle of 104.5°. The two lone pairs push against the bonding pairs, further decreasing the angle from the tetrahedral ideal.
More exotic molecules with 3 bonding pairs and 2 lone pairs form a T-shaped arrangement. Here, bond angles are less than 90° and less than 120° due to significant repulsion from the lone pairs. Chlorine trifluoride (ClF₃) displays this unusual geometry.
🔍 Lone pairs occupy more space than bonding pairs because they're only attracted to one nucleus, causing greater repulsion and distorting the expected bond angles.
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Special Molecular Arrangements
Some molecules exhibit particularly distinctive shapes, such as those with 4 bonding pairs and 2 lone pairs. These molecules form a square planar arrangement with 90° bond angles between adjacent bonds. The lone pairs position themselves 180° apart to minimize repulsion.
In square planar molecules, all four bonding atoms lie in the same plane, creating a flat, square-shaped structure. This arrangement is commonly seen in coordination compounds like ²⁻, where the central platinum atom is surrounded by four chloride ions.
The square planar geometry is quite distinctive because the lone pairs occupy positions above and below the plane of the bonding atoms. This creates an area of high electron density perpendicular to the molecular plane, affecting how these molecules interact with other species.
💡 Square planar molecules often display interesting chemical properties and reactivity patterns due to their open coordination sites perpendicular to the molecular plane.
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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