Biology
Chemistry
AP Chemistry
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Katie Rose
12/6/2025
Chemistry
Transition Metals
380
•
Dec 6, 2025
•
Katie Rose
@katierose
Transition metals are the workhorses of chemistry - they're everywhere... Show more
Transition metals sit between groups 2 and 3 on the periodic table and are called d-block elements because they have an incomplete d subshell in at least one of their ions. This is what gives them their special properties that other metals just don't have.
Most d orbitals fill up following the normal aufbau principle, but chromium and copper are rebels - they break the rules because having a half-filled or completely filled d subshell is more stable. When these metals form ions, they always lose their 4s electrons first, not the 3d ones.
Oxidation states are basically how many electrons an atom has gained or lost when it's part of a compound. Transition metals are brilliant because they can have multiple oxidation states, which explains why they form compounds with different colours.
Quick Tip: Remember that oxidation numbers in a neutral compound always add up to zero - this is your go-to check when working out oxidation states!
Working out oxidation numbers is actually straightforward once you know the rules. Elements on their own are always zero, single-atom ions equal their charge, oxygen is usually -2, and hydrogen is usually +1.
Transition metals can exist in different oxidation states within their compounds, and this flexibility makes them incredibly useful. High oxidation states often make compounds that are oxidising agents, while low oxidation states tend to create reducing agents.
The stability of different oxidation states depends on electronic structure, bonding type, and stereochemistry. This is why some oxidation states are more common than others for each metal.
Remember: Oxidation = increase in oxidation number, Reduction = decrease in oxidation number. OIL RIG still works!
Ligands are electron donors that attach to transition metal ions to form coordination compounds or complexes. Think of them as molecules or ions with lone pairs of electrons that can form coordinate bonds with the metal.
Ligands are classified by how many bonds they can form - monodentate (one bond), bidentate (two bonds), up to hexadentate (six bonds). The coordination number tells you how many bonds the central metal ion has to ligands, which determines the shape of the complex.
Naming complexes follows specific rules that might seem complicated at first, but they're logical. You write ligands alphabetically, add prefixes for multiples (di, tri, tetra), and change endings for negative ion ligands to end in 'o'. Common ligands like water become 'aqua' and ammonia becomes 'ammine'.
Pro Tip: The formula goes in square brackets with the overall charge outside - this makes it clear what's part of the complex!
The amazing colours of transition metal complexes come from d-d transitions. When ligands approach the metal ion, they split the d orbitals into different energy levels. Electrons can jump between these levels when they absorb light energy.
The spectrochemical series ranks ligands by their ability to split d orbitals. Strong field ligands like CN⁻ cause large energy gaps, while weak field ligands like I⁻ cause smaller gaps. You see the complementary colour to whatever's absorbed.
Transition metals make excellent catalysts because of their variable oxidation states and available d orbitals. Heterogeneous catalysts are in a different state to reactants, whilst homogeneous catalysts are in the same state. Both work by providing alternative reaction pathways with lower activation energies.
Key Point: Catalyst poisoning happens when substances bind irreversibly to active sites, so industrial processes need to be carefully controlled!
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.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Quotes from every main character
English LiteratureApp Store
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
Katie Rose
@katierose
Transition metals are the workhorses of chemistry - they're everywhere from the coins in your pocket to the catalysts that make industrial processes possible. These d-block elements have some seriously cool properties that make them stand out from other metals,... Show more
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Transition metals sit between groups 2 and 3 on the periodic table and are called d-block elements because they have an incomplete d subshell in at least one of their ions. This is what gives them their special properties that other metals just don't have.
Most d orbitals fill up following the normal aufbau principle, but chromium and copper are rebels - they break the rules because having a half-filled or completely filled d subshell is more stable. When these metals form ions, they always lose their 4s electrons first, not the 3d ones.
Oxidation states are basically how many electrons an atom has gained or lost when it's part of a compound. Transition metals are brilliant because they can have multiple oxidation states, which explains why they form compounds with different colours.
Quick Tip: Remember that oxidation numbers in a neutral compound always add up to zero - this is your go-to check when working out oxidation states!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Working out oxidation numbers is actually straightforward once you know the rules. Elements on their own are always zero, single-atom ions equal their charge, oxygen is usually -2, and hydrogen is usually +1.
Transition metals can exist in different oxidation states within their compounds, and this flexibility makes them incredibly useful. High oxidation states often make compounds that are oxidising agents, while low oxidation states tend to create reducing agents.
The stability of different oxidation states depends on electronic structure, bonding type, and stereochemistry. This is why some oxidation states are more common than others for each metal.
Remember: Oxidation = increase in oxidation number, Reduction = decrease in oxidation number. OIL RIG still works!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Ligands are electron donors that attach to transition metal ions to form coordination compounds or complexes. Think of them as molecules or ions with lone pairs of electrons that can form coordinate bonds with the metal.
Ligands are classified by how many bonds they can form - monodentate (one bond), bidentate (two bonds), up to hexadentate (six bonds). The coordination number tells you how many bonds the central metal ion has to ligands, which determines the shape of the complex.
Naming complexes follows specific rules that might seem complicated at first, but they're logical. You write ligands alphabetically, add prefixes for multiples (di, tri, tetra), and change endings for negative ion ligands to end in 'o'. Common ligands like water become 'aqua' and ammonia becomes 'ammine'.
Pro Tip: The formula goes in square brackets with the overall charge outside - this makes it clear what's part of the complex!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The amazing colours of transition metal complexes come from d-d transitions. When ligands approach the metal ion, they split the d orbitals into different energy levels. Electrons can jump between these levels when they absorb light energy.
The spectrochemical series ranks ligands by their ability to split d orbitals. Strong field ligands like CN⁻ cause large energy gaps, while weak field ligands like I⁻ cause smaller gaps. You see the complementary colour to whatever's absorbed.
Transition metals make excellent catalysts because of their variable oxidation states and available d orbitals. Heterogeneous catalysts are in a different state to reactants, whilst homogeneous catalysts are in the same state. Both work by providing alternative reaction pathways with lower activation energies.
Key Point: Catalyst poisoning happens when substances bind irreversibly to active sites, so industrial processes need to be carefully controlled!
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.
You can download the app in the Google Play Store and in the Apple App Store.
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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Explore the fundamentals of oxidation and reduction in this detailed summary. Understand key concepts such as oxidizing and reducing agents, oxidation states, and electronegativity. Ideal for A-Level chemistry students preparing for exams, this resource covers essential redox reactions and their applications in various compounds.
ChemistryExplore key concepts in transition metals, periodicity, and group trends with this comprehensive summary. Understand oxidation states, catalytic properties, complex ion formation, and the reactivity of groups 2 and 7. Ideal for AQA A-Level chemistry students seeking to enhance their understanding of the periodic table and related chemical reactions.
ChemistryQuotes from every main character
English LiteratureApp Store
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
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