These notes cover the key properties of carbon allotropes and... Show more
Chemistry88 views·Updated Jun 3, 2026·3 pagesGCSE Chemistry Unit 3: Quantitative Chemistry Notes
Erin@erin_agwa
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Carbon Structures and Mass Conservation
Ever wondered why pencil lead conducts electricity but diamond doesn't? It's all about how carbon atoms bond together! Graphite has each carbon atom making 3 bonds with delocalised electrons that can move freely, making it conductive and soft as its hexagonal sheets slide over each other.
Diamond takes a completely different approach - each carbon atom bonds to 4 others, creating an incredibly hard structure with no free electrons. That's why it can't conduct electricity but makes brilliant cutting tools.
Graphene is basically a single layer of graphite that still conducts electricity, whilst fullerenes like C60 are football-shaped molecules made of 60 carbon atoms. Silicon dioxide behaves similarly to diamond - high melting point but no electrical conductivity.
Key Point: The way atoms bond determines the material's properties - same element, completely different characteristics!
Here's something crucial for your calculations: no atoms disappear during chemical reactions. The mass of what you start with (reactants) always equals the mass of what you end up with (products). This is why balancing symbol equations matters so much for your exams.
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Calculations with Moles and Concentration
Calculating relative formula mass (Mr) becomes straightforward once you know the pattern. Take sodium oxide (Na₂O): you've got 2 sodium atoms (2 × 23) plus 1 oxygen atom (1 × 16) = 62. Always multiply the number of atoms by their relative atomic mass.
Moles represent Avogadro's constant (6.02 × 10²³) - that's an enormous number of particles! The key formula you'll use constantly is: Mass = Mr × moles. This relationship helps you predict how much product you'll get from any reaction.
Let's tackle a real example: if you start with 510g of Al₂O₃, you can work out that this equals 5 moles (510g ÷ 102). From the balanced equation, this produces 10 moles of aluminium, which weighs 270g.
Top Tip: Always start by finding the moles of what you're given, then use the balanced equation ratios to find what you need!
Concentration measures dissolved particles (solute) in a set volume of liquid (solvent). Use the formula: concentration = mass ÷ volume. Remember that 1000cm³ equals 1dm³. The limiting reactant runs out first and determines how much product you can make.
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Chemistry88 views·Updated Jun 3, 2026·3 pagesGCSE Chemistry Unit 3: Quantitative Chemistry Notes
Erin@erin_agwa
These notes cover the key properties of carbon allotropes and silicon dioxide, followed by essential quantitative chemistry concepts including mass conservation, moles, and concentration calculations. You'll also learn about metal reactivity and how different metals behave with acids, water, and... Show more
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Carbon Structures and Mass Conservation
Ever wondered why pencil lead conducts electricity but diamond doesn't? It's all about how carbon atoms bond together! Graphite has each carbon atom making 3 bonds with delocalised electrons that can move freely, making it conductive and soft as its hexagonal sheets slide over each other.
Diamond takes a completely different approach - each carbon atom bonds to 4 others, creating an incredibly hard structure with no free electrons. That's why it can't conduct electricity but makes brilliant cutting tools.
Graphene is basically a single layer of graphite that still conducts electricity, whilst fullerenes like C60 are football-shaped molecules made of 60 carbon atoms. Silicon dioxide behaves similarly to diamond - high melting point but no electrical conductivity.
Key Point: The way atoms bond determines the material's properties - same element, completely different characteristics!
Here's something crucial for your calculations: no atoms disappear during chemical reactions. The mass of what you start with (reactants) always equals the mass of what you end up with (products). This is why balancing symbol equations matters so much for your exams.
2
of 3Sign up to see the content. It's free!
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Calculations with Moles and Concentration
Calculating relative formula mass (Mr) becomes straightforward once you know the pattern. Take sodium oxide (Na₂O): you've got 2 sodium atoms (2 × 23) plus 1 oxygen atom (1 × 16) = 62. Always multiply the number of atoms by their relative atomic mass.
Moles represent Avogadro's constant (6.02 × 10²³) - that's an enormous number of particles! The key formula you'll use constantly is: Mass = Mr × moles. This relationship helps you predict how much product you'll get from any reaction.
Let's tackle a real example: if you start with 510g of Al₂O₃, you can work out that this equals 5 moles (510g ÷ 102). From the balanced equation, this produces 10 moles of aluminium, which weighs 270g.
Top Tip: Always start by finding the moles of what you're given, then use the balanced equation ratios to find what you need!
Concentration measures dissolved particles (solute) in a set volume of liquid (solvent). Use the formula: concentration = mass ÷ volume. Remember that 1000cm³ equals 1dm³. The limiting reactant runs out first and determines how much product you can make.
3
of 3Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
We thought you’d never ask...
What is the Knowunity AI companion?
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.
Where can I download the Knowunity app?
You can download the app from Google Play Store and 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: Law of Conservation of Mass
2Most popular content in Chemistry
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google 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 SiOS 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 KlichAndroid 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.
AnnaiOS user