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Exploring Complex Ion Shapes: Chapter 24.2

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sheila

12/6/2025

Chemistry

Chapter 24.2 - The Formation of Shapes of Complex Ions

52

Dec 6, 2025

4 pages

Exploring Complex Ion Shapes: Chapter 24.2

Complex ions are fascinating chemical structures where molecules or ions... Show more

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24.2-Formation and shapes of complexions

Key Facts:

Notes:
Complex ion
-formed where one or more molecules or
negative ions bond to a cent

Complex Ion Formation

Ever wondered how metal ions can hold onto other molecules so tightly? Complex ions form when one or more molecules or negative ions bond directly to a central metal ion. The molecules or ions that attach are called ligands, and they're basically electron donors.

What makes this bonding special is that ligands donate a pair of electrons to the metal ion, creating what's called a coordinate bond (also known as a dative covalent bond). Think of it like the ligand is lending its electrons to the metal.

The overall charge of a complex ion can be positive, negative, or even neutral - it all depends on the charges of the metal ion and ligands involved.

Quick Tip: Remember that ligands are always the electron donors, whilst the metal ion is the electron acceptor!

24.2-Formation and shapes of complexions

Key Facts:

Notes:
Complex ion
-formed where one or more molecules or
negative ions bond to a cent

Coordination Numbers and Examples

The coordination number tells you exactly how many coordinate bonds are attached to the central metal ion. This number is absolutely crucial because it determines the shape of the entire complex.

The most common coordination numbers you'll encounter are 4 and 6. For example, in copper sulfate, you get Cu(H2O)6Cu(H₂O)₆²⁺ - here the coordination number is 6 because six water molecules surround the copper ion.

In this example, water (H₂O) acts as the ligand, donating electron pairs from its oxygen atoms to form coordinate bonds with the central Cu²⁺ ion.

Exam Focus: Always identify the ligand, central metal ion, and coordination number when analysing complex ion formulas!

24.2-Formation and shapes of complexions

Key Facts:

Notes:
Complex ion
-formed where one or more molecules or
negative ions bond to a cent

Types of Ligands

Not all ligands are created equal! Monodentate ligands can only donate one pair of electrons to the central metal atom, forming just one coordinate bond. Water and ammonia are classic examples.

Bidentate ligands are more generous - they donate two pairs of electrons, forming two coordinate bonds with the same metal ion. This creates a sort of "pincer" effect around the metal.

Understanding whether a ligand is monodentate or bidentate helps predict how many ligand molecules will surround the central metal ion and what the final complex will look like.

Memory Aid: "Mono" means one, "bi" means two - think of the number of electron pairs donated!

24.2-Formation and shapes of complexions

Key Facts:

Notes:
Complex ion
-formed where one or more molecules or
negative ions bond to a cent

Complex Ion Shapes

When coordination number is 4, you'll see two possible shapes. Tetrahedral complexes have bond angles of 109.5°, like in CuCl4CuCl₄²⁻ where four chloride ions arrange themselves around copper in a pyramid-like structure.

Square planar complexes also have coordination number 4, but the ligands arrange in a flat square with 90° bond angles. A perfect example is Pt(NH3)4Pt(NH₃)₄²⁺, where four ammonia molecules surround platinum in one plane.

The difference between tetrahedral and square planar often depends on the specific metal ion and its electron configuration. Platinum commonly forms square planar complexes, which is why cis-platin (a cancer treatment drug) has its distinctive flat structure.

Shape Recognition: Tetrahedral = 3D pyramid, Square planar = flat square - knowing this helps predict complex properties!



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Brad T

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Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

David K

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Sudenaz Ocak

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Greenlight Bonnie

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Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

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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

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This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

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

I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️

Thomas R

iOS user

Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades

Brad T

Android user

Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

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

I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend

Aubrey

iOS user

Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

Paul T

iOS user

 

Chemistry

52

Dec 6, 2025

4 pages

Exploring Complex Ion Shapes: Chapter 24.2

Complex ions are fascinating chemical structures where molecules or ions surround a central metal ion, creating unique shapes and properties. Understanding how these complexes form and their different geometries is crucial for A-level chemistry success.

24.2-Formation and shapes of complexions

Key Facts:

Notes:
Complex ion
-formed where one or more molecules or
negative ions bond to a cent

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Complex Ion Formation

Ever wondered how metal ions can hold onto other molecules so tightly? Complex ions form when one or more molecules or negative ions bond directly to a central metal ion. The molecules or ions that attach are called ligands, and they're basically electron donors.

What makes this bonding special is that ligands donate a pair of electrons to the metal ion, creating what's called a coordinate bond (also known as a dative covalent bond). Think of it like the ligand is lending its electrons to the metal.

The overall charge of a complex ion can be positive, negative, or even neutral - it all depends on the charges of the metal ion and ligands involved.

Quick Tip: Remember that ligands are always the electron donors, whilst the metal ion is the electron acceptor!

24.2-Formation and shapes of complexions

Key Facts:

Notes:
Complex ion
-formed where one or more molecules or
negative ions bond to a cent

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

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By signing up you accept Terms of Service and Privacy Policy

Coordination Numbers and Examples

The coordination number tells you exactly how many coordinate bonds are attached to the central metal ion. This number is absolutely crucial because it determines the shape of the entire complex.

The most common coordination numbers you'll encounter are 4 and 6. For example, in copper sulfate, you get Cu(H2O)6Cu(H₂O)₆²⁺ - here the coordination number is 6 because six water molecules surround the copper ion.

In this example, water (H₂O) acts as the ligand, donating electron pairs from its oxygen atoms to form coordinate bonds with the central Cu²⁺ ion.

Exam Focus: Always identify the ligand, central metal ion, and coordination number when analysing complex ion formulas!

24.2-Formation and shapes of complexions

Key Facts:

Notes:
Complex ion
-formed where one or more molecules or
negative ions bond to a cent

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Access to all documents

Improve your grades

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By signing up you accept Terms of Service and Privacy Policy

Types of Ligands

Not all ligands are created equal! Monodentate ligands can only donate one pair of electrons to the central metal atom, forming just one coordinate bond. Water and ammonia are classic examples.

Bidentate ligands are more generous - they donate two pairs of electrons, forming two coordinate bonds with the same metal ion. This creates a sort of "pincer" effect around the metal.

Understanding whether a ligand is monodentate or bidentate helps predict how many ligand molecules will surround the central metal ion and what the final complex will look like.

Memory Aid: "Mono" means one, "bi" means two - think of the number of electron pairs donated!

24.2-Formation and shapes of complexions

Key Facts:

Notes:
Complex ion
-formed where one or more molecules or
negative ions bond to a cent

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Complex Ion Shapes

When coordination number is 4, you'll see two possible shapes. Tetrahedral complexes have bond angles of 109.5°, like in CuCl4CuCl₄²⁻ where four chloride ions arrange themselves around copper in a pyramid-like structure.

Square planar complexes also have coordination number 4, but the ligands arrange in a flat square with 90° bond angles. A perfect example is Pt(NH3)4Pt(NH₃)₄²⁺, where four ammonia molecules surround platinum in one plane.

The difference between tetrahedral and square planar often depends on the specific metal ion and its electron configuration. Platinum commonly forms square planar complexes, which is why cis-platin (a cancer treatment drug) has its distinctive flat structure.

Shape Recognition: Tetrahedral = 3D pyramid, Square planar = flat square - knowing this helps predict complex properties!

We thought you’d never ask...

What is the Knowunity AI companion?

Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.

Where can I download the Knowunity app?

You can download the app in the Google Play Store and in the 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.

Most popular content in Chemistry

Most popular content

Can't find what you're looking for? Explore other subjects.

Students love us — and so will you.

4.9/5

App Store

4.8/5

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

I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️

Thomas R

iOS user

Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades

Brad T

Android user

Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

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

I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend

Aubrey

iOS user

Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

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

I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️

Thomas R

iOS user

Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades

Brad T

Android user

Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

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

I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend

Aubrey

iOS user

Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

Paul T

iOS user