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22 Dec 2025
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Dalton's Atomic Theory Explained: Understanding the Basics of Atoms
Ummi
@ummi_.com
1 / 4
Dalton's Five Key Ideas About Atoms
Dalton's atomic theory revolutionised how we think about matter with five main postulates. First, he proposed that all matter is made of tiny, indivisible particles called atoms - imagine them as the ultimate Lego blocks of the universe.
His second and third ideas work together perfectly. Atoms of the same element are identical in size, mass, and properties, whilst atoms of different elements are completely different. Think of it like this: all hydrogen atoms are identical twins, but hydrogen and oxygen atoms are totally different species.
Quick Check: If you have a piece of pure gold, every single gold atom in it will be exactly the same!
The beauty of these ideas is that they explained why elements behave consistently - because their atoms are uniform building blocks.
How Atoms Behave in Chemical Reactions
Dalton's fourth postulate was revolutionary: atoms cannot be created or destroyed in chemical reactions. They simply rearrange themselves, like switching dance partners. This explained why mass is always conserved in reactions.
His fifth idea states that atoms combine in simple whole-number ratios to form compounds. Water always has 2 hydrogen atoms for every 1 oxygen atom - never 1.5 or 2.3!
Real-World Connection: This is why recipes work consistently - the 'ingredients' (atoms) always combine in fixed proportions.
These concepts gave scientists the tools to understand conservation of mass and explain important laws like the law of definite proportions - why compounds always have the same composition.
What Dalton Got Right and Wrong
Dalton's theory brilliantly explained the law of multiple proportions. When elements form different compounds, they do so in simple ratios. Carbon and oxygen can make CO (1:1 ratio) or CO₂ (1:2 ratio) - neat whole numbers!
However, later discoveries showed some major limitations. Dalton didn't know about subatomic particles like protons, neutrons, and electrons. He also assumed all atoms of an element were identical, but we now know about isotopes - atoms of the same element with different masses.
Think About It: Dalton's theory was like having a brilliant rough sketch that later scientists could refine into a detailed masterpiece.
His theory also couldn't explain how atoms actually arrange themselves in molecules, which became crucial for understanding chemical behaviour.
Why Dalton's Theory Still Matters Today
Despite its limitations, Dalton's atomic theory was absolutely groundbreaking and laid the foundation for modern chemistry. It gave scientists their first proper framework for understanding matter's composition and behaviour.
Think of Dalton as the pioneer who opened the door to atomic science. His ideas were so influential that they paved the way for every major discovery that followed, from the periodic table to nuclear physics.
Bottom Line: Even though we've refined his ideas, Dalton's core concept that matter is made of atoms remains the cornerstone of chemistry today.
The significance of his work cannot be overstated - it transformed chemistry from a collection of observations into a proper science with predictable rules and patterns.
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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
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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
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Best app on earth! no words because it’s too good
Thomas R
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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
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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
Dalton's Atomic Theory Explained: Understanding the Basics of Atoms
Ummi
@ummi_.com
Ever wondered what makes up everything around you? John Dalton, a brilliant English scientist from the early 1800s, came up with the first proper theory about atoms - the tiny building blocks that make up absolutely everything in our world.
Dalton's Five Key Ideas About Atoms
Dalton's atomic theory revolutionised how we think about matter with five main postulates. First, he proposed that all matter is made of tiny, indivisible particles called atoms - imagine them as the ultimate Lego blocks of the universe.
His second and third ideas work together perfectly. Atoms of the same element are identical in size, mass, and properties, whilst atoms of different elements are completely different. Think of it like this: all hydrogen atoms are identical twins, but hydrogen and oxygen atoms are totally different species.
Quick Check: If you have a piece of pure gold, every single gold atom in it will be exactly the same!
The beauty of these ideas is that they explained why elements behave consistently - because their atoms are uniform building blocks.
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How Atoms Behave in Chemical Reactions
Dalton's fourth postulate was revolutionary: atoms cannot be created or destroyed in chemical reactions. They simply rearrange themselves, like switching dance partners. This explained why mass is always conserved in reactions.
His fifth idea states that atoms combine in simple whole-number ratios to form compounds. Water always has 2 hydrogen atoms for every 1 oxygen atom - never 1.5 or 2.3!
Real-World Connection: This is why recipes work consistently - the 'ingredients' (atoms) always combine in fixed proportions.
These concepts gave scientists the tools to understand conservation of mass and explain important laws like the law of definite proportions - why compounds always have the same composition.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
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What Dalton Got Right and Wrong
Dalton's theory brilliantly explained the law of multiple proportions. When elements form different compounds, they do so in simple ratios. Carbon and oxygen can make CO (1:1 ratio) or CO₂ (1:2 ratio) - neat whole numbers!
However, later discoveries showed some major limitations. Dalton didn't know about subatomic particles like protons, neutrons, and electrons. He also assumed all atoms of an element were identical, but we now know about isotopes - atoms of the same element with different masses.
Think About It: Dalton's theory was like having a brilliant rough sketch that later scientists could refine into a detailed masterpiece.
His theory also couldn't explain how atoms actually arrange themselves in molecules, which became crucial for understanding chemical behaviour.
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Improve your grades
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Why Dalton's Theory Still Matters Today
Despite its limitations, Dalton's atomic theory was absolutely groundbreaking and laid the foundation for modern chemistry. It gave scientists their first proper framework for understanding matter's composition and behaviour.
Think of Dalton as the pioneer who opened the door to atomic science. His ideas were so influential that they paved the way for every major discovery that followed, from the periodic table to nuclear physics.
Bottom Line: Even though we've refined his ideas, Dalton's core concept that matter is made of atoms remains the cornerstone of chemistry today.
The significance of his work cannot be overstated - it transformed chemistry from a collection of observations into a proper science with predictable rules and patterns.
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.
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4.9/5
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4.8/5
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