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Chemistry
30 Nov 2025
391
3 pages
Ever wondered why table salt fizzes when it meets water, or why some elements are so eager to... Show more
Think of alkali metals as the most sociable elements on the periodic table - they absolutely hate being alone! Group 1 includes lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs) and francium (Fr).
Here's the fascinating bit these metals become more reactive as you travel down the group. So lithium is quite mild-mannered, but caesium is explosively reactive! This happens because each element down the group has one more electron shell than the one above it.
The extra shells mean the outer electron gets further from the nucleus, making it easier to lose. Since alkali metals desperately want to give away their single outer electron, more shells equals more reactivity.
Quick Tip Remember "Down = More Dangerous" for Group 1 reactivity!
Halogens are basically the opposite of alkali metals - they're the "electron thieves" of chemistry! The name halogen comes from Greek meaning "salt-maker" because they love combining with metals to form salts.
The halogen family includes fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (As). There's also tessennine (Ts), but it's so rare and unstable that it barely counts!
Unlike Group 1, halogens get more reactive as you go up the group. Fluorine at the top is absolutely vicious, whilst iodine at the bottom is relatively calm. They also get darker in colour as you move down - fluorine is pale yellow, chlorine is green, bromine is orange-red, and iodine is dark purple.
Memory Trick Halogens are "Upwardly Mobile" - more reactive going up!
When halogens steal electrons from other elements, they become halides - negatively charged ions that are brilliant at forming salts. Think of common table salt (sodium chloride) - that's a classic halogen-alkali metal partnership!
This opposite reactivity pattern between Groups 1 and 7 makes perfect chemical sense. Alkali metals desperately want to lose an electron, whilst halogens are equally desperate to gain one.
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.
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Explore the fundamentals of atomic structure and the periodic table in this comprehensive summary. Understand electron configurations, atomic particles, and the classification of elements into metals, non-metals, and metalloids. Ideal for chemistry students preparing for exams or seeking to reinforce their knowledge of key concepts in atomic theory and the periodic table.
ChemistryExplore the properties of transition metals, alkali metals, and halogens, including their reactivity trends, atomic structure, and applications. This summary covers key concepts such as metallic bonding, noble gases, and the periodic table organization, making it essential for chemistry students preparing for exams.
ChemistryExplore the reactivity of alkali metals and halogens through displacement reactions and chemical equations. This study note includes practice questions, detailed explanations of periodic trends, and insights into balancing equations. Ideal for exam preparation in chemistry.
ChemistryExplore the properties and reactivity of alkali metals in Group 1 of the periodic table. This summary covers their electron configuration, low melting points, and vigorous reactions with water, including the formation of hydroxides and hydrogen gas. Ideal for students studying chemistry concepts related to periodic trends and ionic bonding.
ChemistryExplore the reactivity trends of Group 1 alkali metals and Group 7 halogens in this detailed summary. Understand how their electron configurations influence their chemical behavior, including comparisons with Group 2 metals and Group 0 noble gases. Key concepts include periodic trends, melting and boiling points, and the significance of electron shells. Ideal for GCSE Chemistry students preparing for exams.
ChemistryExplore the properties and reactions of alkali metals, halogens, and noble gases in this detailed summary. Understand the unique characteristics of each group, including their electron configurations, reactivity, and industrial applications. Ideal for GCSE chemistry students looking to grasp key concepts in atomic structure and bonding.
ChemistryApp 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
Best app on earth! no words because itโs 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 didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm 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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 itโs 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 didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm 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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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
Ever wondered why table salt fizzes when it meets water, or why some elements are so eager to react whilst others seem quite calm? Let's explore two fascinating groups from the periodic table that showcase completely opposite patterns of reactivity.
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Think of alkali metals as the most sociable elements on the periodic table - they absolutely hate being alone! Group 1 includes lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs) and francium (Fr).
Here's the fascinating bit: these metals become more reactive as you travel down the group. So lithium is quite mild-mannered, but caesium is explosively reactive! This happens because each element down the group has one more electron shell than the one above it.
The extra shells mean the outer electron gets further from the nucleus, making it easier to lose. Since alkali metals desperately want to give away their single outer electron, more shells equals more reactivity.
Quick Tip: Remember "Down = More Dangerous" for Group 1 reactivity!
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Improve your grades
Join milions of students
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Halogens are basically the opposite of alkali metals - they're the "electron thieves" of chemistry! The name halogen comes from Greek meaning "salt-maker" because they love combining with metals to form salts.
The halogen family includes fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (As). There's also tessennine (Ts), but it's so rare and unstable that it barely counts!
Unlike Group 1, halogens get more reactive as you go up the group. Fluorine at the top is absolutely vicious, whilst iodine at the bottom is relatively calm. They also get darker in colour as you move down - fluorine is pale yellow, chlorine is green, bromine is orange-red, and iodine is dark purple.
Memory Trick: Halogens are "Upwardly Mobile" - more reactive going up!
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Improve your grades
Join milions of students
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When halogens steal electrons from other elements, they become halides - negatively charged ions that are brilliant at forming salts. Think of common table salt (sodium chloride) - that's a classic halogen-alkali metal partnership!
This opposite reactivity pattern between Groups 1 and 7 makes perfect chemical sense. Alkali metals desperately want to lose an electron, whilst halogens are equally desperate to gain one.
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.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help โ all at your fingertips.
10
Smart Tools NEW
Transform this note into: โ 50+ Practice Questions โ Interactive Flashcards โ Full Mock Exam โ Essay Outlines
Explore the fundamentals of atomic structure and the periodic table in this comprehensive summary. Understand electron configurations, atomic particles, and the classification of elements into metals, non-metals, and metalloids. Ideal for chemistry students preparing for exams or seeking to reinforce their knowledge of key concepts in atomic theory and the periodic table.
ChemistryExplore the properties of transition metals, alkali metals, and halogens, including their reactivity trends, atomic structure, and applications. This summary covers key concepts such as metallic bonding, noble gases, and the periodic table organization, making it essential for chemistry students preparing for exams.
ChemistryExplore the reactivity of alkali metals and halogens through displacement reactions and chemical equations. This study note includes practice questions, detailed explanations of periodic trends, and insights into balancing equations. Ideal for exam preparation in chemistry.
ChemistryExplore the properties and reactivity of alkali metals in Group 1 of the periodic table. This summary covers their electron configuration, low melting points, and vigorous reactions with water, including the formation of hydroxides and hydrogen gas. Ideal for students studying chemistry concepts related to periodic trends and ionic bonding.
ChemistryExplore the reactivity trends of Group 1 alkali metals and Group 7 halogens in this detailed summary. Understand how their electron configurations influence their chemical behavior, including comparisons with Group 2 metals and Group 0 noble gases. Key concepts include periodic trends, melting and boiling points, and the significance of electron shells. Ideal for GCSE Chemistry students preparing for exams.
ChemistryExplore the properties and reactions of alkali metals, halogens, and noble gases in this detailed summary. Understand the unique characteristics of each group, including their electron configurations, reactivity, and industrial applications. Ideal for GCSE chemistry students looking to grasp key concepts in atomic structure and bonding.
ChemistryApp 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
Best app on earth! no words because itโs 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 didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm 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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 itโs 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 didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm 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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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
Sociology