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Claire 1218
12/3/2025
Chemistry
Intro to Significant Figures
210
•
Dec 3, 2025
•
Understanding Significant Figures: A Beginner's Guide
C
Claire 1218
@claire1218_hfue
1 / 4
Describing Substances and Chemical Changes
The periodic table organizes all unique, pure elements, each with its own symbol like C (carbon), Hg (mercury), and Mg (magnesium). When elements combine, they create something new - a compound.
Compounds are molecules containing two or more elements chemically combined in fixed proportions. These compounds have properties completely different from the original elements. Remember that while all compounds are molecules, not all molecules are compounds!
We use chemical formulas to show exactly what's in a compound by indicating the types and numbers of atoms present. When these substances undergo chemical reactions, we represent this with equations showing reactants (inputs) transforming into products (outputs) using an arrow (→).
💡 The Law of Conservation of Matter is like a chemistry accounting system: atoms can't disappear or appear out of nowhere during reactions. The number of each type of atom must be the same on both sides of a chemical equation.
Recognizing Reactions and Making Measurements
You can spot a chemical reaction happening through three main signs: a color change, gas bubbles forming, or a precipitate (solid) appearing. These visual clues tell you that chemical bonds are breaking and forming.
In science, numbers always measure something specific (like 3.478 grams). How we handle these measurements depends on both accuracy (how close to the true value) and precision (how consistent repeated measurements are).
Measurements can have two types of errors: random errors that vary high or low unpredictably, and systematic errors that consistently lean in one direction due to technique problems or calibration issues.
🔍 When counting significant figures in measurements, remember: leading zeros don't count (0.0486 has 3 sig figs), captive zeros always count (16.07 has 4), and trailing zeros only count if there's a decimal point (9.300 has 4 but 100 has just 1).
Mathematical Operations and Physical Changes
When multiplying and dividing measurements, your answer should have the same number of significant figures as your least precise measurement. For example, 6.38 × 2.0 = 13 (rounded to 2 sig figs, not 12.76).
Scientific notation helps us manage very large or small numbers by writing them as M × 10^n, where M is between 1 and 10. To convert 2,500,000,000, first identify where to place the decimal (2.5), then count decimal moves (9), resulting in 2.5 × 10^9.
Physical changes don't create new substances but alter a substance's appearance or state. Examples include condensing, evaporating, bubbling, sublimation, perspiration, and deposition.
🧊 During physical changes like ice expanding, the substance's identity stays the same—it's still water, just in a different form. This differs from chemical changes where new substances form.
More Physical Changes and Oxidation
Dissolving and distillation are important physical changes we use to separate mixtures. In dissolving, a substance spreads throughout a liquid without changing its chemical makeup. Distillation uses differences in boiling points to separate liquids.
Oxidation is actually a chemical change, not physical. Scientist Oliver Sacks noted when roasting metals that there was no weight gain or loss during oxidation, supporting the law of conservation of matter.
Physical changes can be dramatic but don't create new substances. For example, when ice expands, it might crack containers, but it's still H₂O—just arranged differently.
🔥 When distinguishing between physical and chemical changes, ask yourself: "Is this the same substance before and after?" If yes (like water to ice), it's physical. If no (like wood to ash), it's chemical.
We thought you’d never ask...
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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
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Understanding Significant Figures: A Beginner's Guide
C
Claire 1218
@claire1218_hfue
Chemistry is all about understanding substances and how they change. When elements combine, they form compounds with new properties. This introduction to chemistry covers how we describe these substances, recognize chemical reactions, and apply important measurement principles.
Describing Substances and Chemical Changes
The periodic table organizes all unique, pure elements, each with its own symbol like C (carbon), Hg (mercury), and Mg (magnesium). When elements combine, they create something new - a compound.
Compounds are molecules containing two or more elements chemically combined in fixed proportions. These compounds have properties completely different from the original elements. Remember that while all compounds are molecules, not all molecules are compounds!
We use chemical formulas to show exactly what's in a compound by indicating the types and numbers of atoms present. When these substances undergo chemical reactions, we represent this with equations showing reactants (inputs) transforming into products (outputs) using an arrow (→).
💡 The Law of Conservation of Matter is like a chemistry accounting system: atoms can't disappear or appear out of nowhere during reactions. The number of each type of atom must be the same on both sides of a chemical equation.
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By signing up you accept Terms of Service and Privacy Policy
Recognizing Reactions and Making Measurements
You can spot a chemical reaction happening through three main signs: a color change, gas bubbles forming, or a precipitate (solid) appearing. These visual clues tell you that chemical bonds are breaking and forming.
In science, numbers always measure something specific (like 3.478 grams). How we handle these measurements depends on both accuracy (how close to the true value) and precision (how consistent repeated measurements are).
Measurements can have two types of errors: random errors that vary high or low unpredictably, and systematic errors that consistently lean in one direction due to technique problems or calibration issues.
🔍 When counting significant figures in measurements, remember: leading zeros don't count (0.0486 has 3 sig figs), captive zeros always count (16.07 has 4), and trailing zeros only count if there's a decimal point (9.300 has 4 but 100 has just 1).
Sign up to see the contentIt's free!
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Mathematical Operations and Physical Changes
When multiplying and dividing measurements, your answer should have the same number of significant figures as your least precise measurement. For example, 6.38 × 2.0 = 13 (rounded to 2 sig figs, not 12.76).
Scientific notation helps us manage very large or small numbers by writing them as M × 10^n, where M is between 1 and 10. To convert 2,500,000,000, first identify where to place the decimal (2.5), then count decimal moves (9), resulting in 2.5 × 10^9.
Physical changes don't create new substances but alter a substance's appearance or state. Examples include condensing, evaporating, bubbling, sublimation, perspiration, and deposition.
🧊 During physical changes like ice expanding, the substance's identity stays the same—it's still water, just in a different form. This differs from chemical changes where new substances form.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
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More Physical Changes and Oxidation
Dissolving and distillation are important physical changes we use to separate mixtures. In dissolving, a substance spreads throughout a liquid without changing its chemical makeup. Distillation uses differences in boiling points to separate liquids.
Oxidation is actually a chemical change, not physical. Scientist Oliver Sacks noted when roasting metals that there was no weight gain or loss during oxidation, supporting the law of conservation of matter.
Physical changes can be dramatic but don't create new substances. For example, when ice expands, it might crack containers, but it's still H₂O—just arranged differently.
🔥 When distinguishing between physical and chemical changes, ask yourself: "Is this the same substance before and after?" If yes (like water to ice), it's physical. If no (like wood to ash), it's chemical.
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the 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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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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user