Ever wondered why your phone's screen doesn't shatter like glass... Show more
Chemistry152 views·Updated May 31, 2026·2 pagesAQA Combined Science: Chemistry Paper 1
A
arrianne@arr1
1
of 2
Atomic Models and the Periodic Table
Scientists have been trying to figure out what atoms actually look like for centuries, and each discovery built on the last one. It started with Dalton thinking atoms were just tiny spheres, then Thomson discovered electrons and imagined the "plum pudding model" - a ball of positive charge with electrons scattered throughout.
Everything changed when Rutherford fired particles at gold foil and discovered most of the atom is empty space with a dense nucleus at the centre. Bohr then worked out that electrons orbit in specific shells around the nucleus, and finally Chadwick discovered neutrons hiding in the nucleus alongside protons.
The periodic table makes so much more sense once you understand electron shells! Elements in the same group (like Group 1 alkali metals) have identical numbers of outer shell electrons, which is why they behave similarly. Group 1 elements all have just one electron in their outer shell, making them dead reactive.
Quick Tip: Group 1 metals get more reactive as you go down (lithium is calmer than sodium, which is calmer than potassium), whilst Group 7 halogens get less reactive as you go down!
2
of 2
Chemical Bonding and Material Properties
Here's the golden rule that explains everything: elements are most stable when they have full outer shells. This drives all chemical bonding, and there are three main types you need to know inside out.
Ionic bonding happens when metals give electrons to non-metals, creating charged ions that form giant lattices. These conduct electricity when molten because the ions can move around freely. Covalent bonding involves non-metals sharing electrons - think water or carbon dioxide. Metallic bonding creates that sea of delocalised electrons that lets metals conduct electricity and makes them bendy rather than brittle.
The structure determines the properties completely. Diamond has every carbon making four strong bonds, creating an incredibly hard material that can't conduct electricity. Graphite has carbons making only three bonds each, leaving delocalised electrons free to conduct electricity whilst the layered structure makes it slippery.
Remember: Small covalent molecules (like water) are usually gases or liquids with weak forces between molecules, whilst giant structures (like diamond) are solid with strong bonds throughout.
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Chemistry152 views·Updated May 31, 2026·2 pagesAQA Combined Science: Chemistry Paper 1
A
arrianne@arr1
Ever wondered why your phone's screen doesn't shatter like glass or why salt dissolves in water but oil doesn't? It all comes down to atomic structure and chemical bonding! Understanding how atoms are built and how they stick together explains... Show more
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Atomic Models and the Periodic Table
Scientists have been trying to figure out what atoms actually look like for centuries, and each discovery built on the last one. It started with Dalton thinking atoms were just tiny spheres, then Thomson discovered electrons and imagined the "plum pudding model" - a ball of positive charge with electrons scattered throughout.
Everything changed when Rutherford fired particles at gold foil and discovered most of the atom is empty space with a dense nucleus at the centre. Bohr then worked out that electrons orbit in specific shells around the nucleus, and finally Chadwick discovered neutrons hiding in the nucleus alongside protons.
The periodic table makes so much more sense once you understand electron shells! Elements in the same group (like Group 1 alkali metals) have identical numbers of outer shell electrons, which is why they behave similarly. Group 1 elements all have just one electron in their outer shell, making them dead reactive.
Quick Tip: Group 1 metals get more reactive as you go down (lithium is calmer than sodium, which is calmer than potassium), whilst Group 7 halogens get less reactive as you go down!
2
of 2Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Chemical Bonding and Material Properties
Here's the golden rule that explains everything: elements are most stable when they have full outer shells. This drives all chemical bonding, and there are three main types you need to know inside out.
Ionic bonding happens when metals give electrons to non-metals, creating charged ions that form giant lattices. These conduct electricity when molten because the ions can move around freely. Covalent bonding involves non-metals sharing electrons - think water or carbon dioxide. Metallic bonding creates that sea of delocalised electrons that lets metals conduct electricity and makes them bendy rather than brittle.
The structure determines the properties completely. Diamond has every carbon making four strong bonds, creating an incredibly hard material that can't conduct electricity. Graphite has carbons making only three bonds each, leaving delocalised electrons free to conduct electricity whilst the layered structure makes it slippery.
Remember: Small covalent molecules (like water) are usually gases or liquids with weak forces between molecules, whilst giant structures (like diamond) are solid with strong bonds throughout.
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: Covalent Network Solids
6Most 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