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Britain & the wider world: 1745 -1901
1l the quest for political stability: germany, 1871-1991
The cold war
Inter-war germany
Medieval period: 1066 -1509
2d religious conflict and the church in england, c1529-c1570
2o democracy and nazism: germany, 1918-1945
1f industrialisation and the people: britain, c1783-1885
1c the tudors: england, 1485-1603
2m wars and welfare: britain in transition, 1906-1957
World war two & the holocaust
2n revolution and dictatorship: russia, 1917-1953
2s the making of modern britain, 1951-2007
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Chemistry
11 Dec 2025
263
5 pages
susie powell @susiepowell_
Chemistry is the fascinating science that explores the composition, properties, and transformation of matter. This guide covers the... Show more
Matter exists in three main states solid, liquid and gas. In solids, particles are arranged in a fixed, regular pattern, vibrating in place with little energy. Liquids have particles with some energy that take the shape of their container's bottom. Gases contain particles with high energy moving randomly with no fixed shape.
These states can transform through processes like melting (solid to liquid), freezing (liquid to solid), evaporation (liquid to gas), and condensation (gas to liquid). Less common transitions include sublimation (solid directly to gas) and deposition (gas directly to solid). These changes involve adjustments in the arrangement, movement, and energy of particles.
When substances dissolve, we get solutions consisting of a solute (the substance that dissolves) and a solvent (the liquid that does the dissolving). A saturated solution occurs when no more solute can dissolve. Solubility is measured in grams per 100g of solvent and varies with temperature.
Did you know? You can create your own solubility curve by measuring how much of a compound dissolves at different temperatures. This is exactly what scientists do to understand how substances behave in solution!
Everything around us can be classified as an element, compound, or mixture. Elements contain only one type of atom, while compounds have two or more types of atoms chemically bonded together. Mixtures contain two or more substances that aren't chemically joined.
You can identify a pure substance by its fixed melting and boiling point. For example, pure water should boil at exactly 100°C. If it boils over a range of temperatures, it's a mixture. This knowledge is crucial for determining the purity of substances in science labs.
Scientists use various separation techniques to isolate components in mixtures. These include simple distillation (separating based on boiling point), filtration (removing solid particles), crystallisation (evaporating to leave crystals), and paper chromatography (separating coloured chemicals). In chromatography, we can calculate Rf values to identify specific components.
Try this! Next time you use coloured pens, try this experiment draw a small dot of each colour on filter paper and dip the edge in water. Watch how different pigments in each ink travel different distances, revealing that many "single colours" are actually mixtures!
The fundamental building blocks of matter are atoms (particles that uniquely define an element) and molecules (groups of atoms bonded together). Each atom consists of protons, neutrons, and electrons with specific positions, relative masses, and charges.
An element's atomic number equals the number of protons in its nucleus, while the mass number equals the sum of protons and neutrons. Isotopes are atoms of the same element with different numbers of neutrons. The relative atomic mass (Ar) is calculated using the abundance of an element's isotopes.
Chemical equations use symbols to represent reactions. You'll need to balance them to show that matter is conserved. Use state symbols (s, l, g, aq) to indicate whether substances are solid, liquid, gas or in aqueous solution. The relative formula mass (Mr) is found by adding the relative atomic masses of all atoms in a compound.
Remember The mole is a crucial unit in chemistry representing 6 × 10^23 particles. The formula mass in grams = 1 mole. This relationship is key for calculating quantities in chemical reactions!
Atoms bond to achieve stable electron configurations. Ionic bonding occurs between metals and non-metals through electron transfer. Metals lose electrons to become positively charged ions, while non-metals gain electrons to become negatively charged ions. The strong electrostatic attraction between these opposite charges forms the bond.
Compounds with giant ionic lattices have high melting and boiling points because substantial energy is needed to overcome the strong electrostatic forces. Ionic compounds don't conduct electricity when solid (ions fixed in place) but do conduct when molten or dissolved (ions free to move).
Covalent bonding happens between non-metals when atoms share electron pairs. The electrostatic attraction between positively charged nuclei and negatively charged shared electrons forms the bond. Substances with simple molecular structures have low melting and boiling points since little energy is needed to overcome the weak intermolecular forces between molecules.
Understanding structures Carbon forms three fascinating structures with very different properties. Diamond (hard, insulating) has each carbon forming 4 bonds in a rigid 3D structure. Graphite (soft, conducting) has carbon in layers with 3 bonds each. C60 fullerene forms hollow sphere-like molecules. These differences perfectly demonstrate how structure determines properties!
Metallic bonding occurs between metal atoms, where outer shell electrons become delocalized and free to move throughout the lattice. The positive metal ions are held in a regular arrangement by attraction to this "sea" of negative electrons. This explains why metals conduct electricity and are malleable (layers can slide over each other without breaking bonds).
Electrolysis is the process of using electricity to split up compounds. In this process, anions (negative ions) are attracted to the anode (positive electrode), while cations (positive ions) are attracted to the cathode (negative electrode). Ionic compounds conduct electricity only when molten or in solution because ions need to move freely.
During electrolysis of molten compounds, the metal ions gain electrons at the cathode to form the metal, while non-metal ions lose electrons at the anode to form molecules. In aqueous solutions, things get more complicated because water molecules provide additional ions . The least reactive ions are discharged first.
Application alert Electrolysis isn't just classroom science—it's used industrially to extract reactive metals like aluminium, purify copper for electrical wiring, and electroplate metals to provide protective or decorative coatings. This process demonstrates chemistry's real-world importance!
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 – all at your fingertips.
8
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Learning one of the foundation skills in chemistry: balancing chemical equations.
ChemistryIncludes definition of lewis structures, examples, differences between single, double, and triple bonds, and steps to draw a lewis structure. Also includes practice problems.
AP ChemistryThe Lewis Dot Structure of Elements of the Periodic Table
ChemistryThis is about recognizing and naming Binary Ionic Compound
Chemistry2 questions each with 2 sub-questions. The questions are solved with the correct solutions
AP 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
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
susie powell
@susiepowell_
Chemistry is the fascinating science that explores the composition, properties, and transformation of matter. This guide covers the fundamental principles of chemistry, from states of matter to atomic structure and bonding, providing you with essential knowledge to understand how our... Show more
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Matter exists in three main states: solid, liquid and gas. In solids, particles are arranged in a fixed, regular pattern, vibrating in place with little energy. Liquids have particles with some energy that take the shape of their container's bottom. Gases contain particles with high energy moving randomly with no fixed shape.
These states can transform through processes like melting (solid to liquid), freezing (liquid to solid), evaporation (liquid to gas), and condensation (gas to liquid). Less common transitions include sublimation (solid directly to gas) and deposition (gas directly to solid). These changes involve adjustments in the arrangement, movement, and energy of particles.
When substances dissolve, we get solutions consisting of a solute (the substance that dissolves) and a solvent (the liquid that does the dissolving). A saturated solution occurs when no more solute can dissolve. Solubility is measured in grams per 100g of solvent and varies with temperature.
Did you know? You can create your own solubility curve by measuring how much of a compound dissolves at different temperatures. This is exactly what scientists do to understand how substances behave in solution!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Everything around us can be classified as an element, compound, or mixture. Elements contain only one type of atom, while compounds have two or more types of atoms chemically bonded together. Mixtures contain two or more substances that aren't chemically joined.
You can identify a pure substance by its fixed melting and boiling point. For example, pure water should boil at exactly 100°C. If it boils over a range of temperatures, it's a mixture. This knowledge is crucial for determining the purity of substances in science labs.
Scientists use various separation techniques to isolate components in mixtures. These include simple distillation (separating based on boiling point), filtration (removing solid particles), crystallisation (evaporating to leave crystals), and paper chromatography (separating coloured chemicals). In chromatography, we can calculate Rf values to identify specific components.
Try this! Next time you use coloured pens, try this experiment: draw a small dot of each colour on filter paper and dip the edge in water. Watch how different pigments in each ink travel different distances, revealing that many "single colours" are actually mixtures!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The fundamental building blocks of matter are atoms (particles that uniquely define an element) and molecules (groups of atoms bonded together). Each atom consists of protons, neutrons, and electrons with specific positions, relative masses, and charges.
An element's atomic number equals the number of protons in its nucleus, while the mass number equals the sum of protons and neutrons. Isotopes are atoms of the same element with different numbers of neutrons. The relative atomic mass (Ar) is calculated using the abundance of an element's isotopes.
Chemical equations use symbols to represent reactions. You'll need to balance them to show that matter is conserved. Use state symbols (s, l, g, aq) to indicate whether substances are solid, liquid, gas or in aqueous solution. The relative formula mass (Mr) is found by adding the relative atomic masses of all atoms in a compound.
Remember: The mole is a crucial unit in chemistry representing 6 × 10^23 particles. The formula mass in grams = 1 mole. This relationship is key for calculating quantities in chemical reactions!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Atoms bond to achieve stable electron configurations. Ionic bonding occurs between metals and non-metals through electron transfer. Metals lose electrons to become positively charged ions, while non-metals gain electrons to become negatively charged ions. The strong electrostatic attraction between these opposite charges forms the bond.
Compounds with giant ionic lattices have high melting and boiling points because substantial energy is needed to overcome the strong electrostatic forces. Ionic compounds don't conduct electricity when solid (ions fixed in place) but do conduct when molten or dissolved (ions free to move).
Covalent bonding happens between non-metals when atoms share electron pairs. The electrostatic attraction between positively charged nuclei and negatively charged shared electrons forms the bond. Substances with simple molecular structures have low melting and boiling points since little energy is needed to overcome the weak intermolecular forces between molecules.
Understanding structures: Carbon forms three fascinating structures with very different properties. Diamond (hard, insulating) has each carbon forming 4 bonds in a rigid 3D structure. Graphite (soft, conducting) has carbon in layers with 3 bonds each. C60 fullerene forms hollow sphere-like molecules. These differences perfectly demonstrate how structure determines properties!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Metallic bonding occurs between metal atoms, where outer shell electrons become delocalized and free to move throughout the lattice. The positive metal ions are held in a regular arrangement by attraction to this "sea" of negative electrons. This explains why metals conduct electricity and are malleable (layers can slide over each other without breaking bonds).
Electrolysis is the process of using electricity to split up compounds. In this process, anions (negative ions) are attracted to the anode (positive electrode), while cations (positive ions) are attracted to the cathode (negative electrode). Ionic compounds conduct electricity only when molten or in solution because ions need to move freely.
During electrolysis of molten compounds, the metal ions gain electrons at the cathode to form the metal, while non-metal ions lose electrons at the anode to form molecules. In aqueous solutions, things get more complicated because water molecules provide additional ions . The least reactive ions are discharged first.
Application alert: Electrolysis isn't just classroom science—it's used industrially to extract reactive metals like aluminium, purify copper for electrical wiring, and electroplate metals to provide protective or decorative coatings. This process demonstrates chemistry's real-world importance!
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 – all at your fingertips.
8
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Learning one of the foundation skills in chemistry: balancing chemical equations.
ChemistryIncludes definition of lewis structures, examples, differences between single, double, and triple bonds, and steps to draw a lewis structure. Also includes practice problems.
AP ChemistryThe Lewis Dot Structure of Elements of the Periodic Table
ChemistryThis is about recognizing and naming Binary Ionic Compound
Chemistry2 questions each with 2 sub-questions. The questions are solved with the correct solutions
AP 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
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
Sociology