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Chemistry
Oct 6, 2025
151
5 pages
The atomic structure and electron configuration of atoms, from early models to quantum mechanical understanding, forms the foundation... Show more
This page delves deeper into the structure of electron energy levels in the quantum mechanical model, introducing the concept of electron configuration.
Principle Energy Levels are the main divisions of electron energy in an atom
Sublevels contain specific types of orbitals
Example The 2nd PEL has quantum number 2, so it contains 2 sublevels 2s and 2p.
Definition Electron configuration is a notation that shows how electrons are distributed in an atom's orbitals.
The Aufbau Principle guides the filling of orbitals
Highlight The order of filling follows a specific pattern 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, etc.
This page provides a foundation for understanding how to write and interpret electron configurations.
This page focuses on the practical application of electron configuration principles, teaching how to write configurations and draw orbital diagrams.
Example For Lithium (Li), with 3 electrons 1sยฒ 2sยน
Orbital diagrams visually represent electron distribution
Highlight Hund's Rule states that electrons occupy orbitals of equal energy individually before pairing up.
Definition The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of quantum numbers. In practice, this means no more than two electrons can occupy the same orbital, and they must have opposite spins.
Examples are provided for elements like Lithium (Li), Beryllium (Be), and Boron (B), showing both electron configurations and orbital diagrams.
This page provides practical guidance for applying quantum mechanical principles to describe electron arrangements in atoms.
This final page explores the concepts of valence electrons and kernel electrons, which are important for understanding chemical behavior and atomic structure.
Definition Valence electrons are the electrons in the outermost principle energy level of an atom.
Valence electrons are crucial for determining an atom's chemical properties and bonding behavior. They can be identified from the electron configuration or Bohr model diagram.
Definition Kernel electrons are all the electrons in the inner energy levels of an atom, excluding the valence electrons.
Kernel electrons typically do not participate in chemical reactions.
Example For Magnesium (Mg) 1sยฒ 2sยฒ 2pโถ 3sยฒ
- Valence electrons 2 (in 3s)
- Kernel electrons 10 (in 1s, 2s, and 2p)
The page includes examples of electron configurations and orbital diagrams for elements like Magnesium (Mg) and Calcium (Ca), highlighting their valence and kernel electrons.
Highlight Understanding valence electrons is crucial for predicting an element's chemical behavior and its position in the periodic table.
This page ties together the concepts of electron configuration with practical applications in chemistry and periodic trends.
Understanding electron configuration helps predict chemical behavior and element properties. This section demonstrates practical applications of electron configuration chart knowledge.
Example For Magnesium (Mg) 1sยฒ 2sยฒ 2pโถ 3sยฒ Shows 2 valence electrons in the outer shell
Vocabulary Valence electrons are those in the outermost principal energy level.
Definition Kernel electrons are all electrons except valence electrons.
The quantum mechanical model of atom represents a significant advancement in our understanding of atomic structure. This page introduces key concepts that differentiate this model from earlier atomic theories.
Definition The quantum mechanical model, also called the charge cloud or orbital model, describes electrons as existing in probability clouds around the nucleus rather than in fixed orbits.
The quantum model builds upon Bohr's concept of energy levels but incorporates important new ideas
Highlight The quantum model explains the bright line spectrum observed when excited electrons return to lower energy states, a phenomenon that supported Bohr's energy level concept.
Vocabulary Quantum - a discrete packet or bundle of energy, as proposed in Planck's theory
This model provides a more accurate and comprehensive description of atomic structure and electron behavior than previous models like the Bohr model or Rutherford atomic model.
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.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help โ all at your fingertips.
14
Smart Tools NEW
Transform this note into: โ 50+ Practice Questions โ Interactive Flashcards โ Full Mock Exam โ Essay Outlines
Basics of Atoms and theory including atom history.
Chemistryexamples of all Atomic Theories
ChemistryExplore the evolution of atomic models, including the Bohr model and the concept of atomic particles. This summary covers key concepts such as atomic structure, electronic configurations, isotopes, and the historical development of atomic theory. Ideal for students seeking a comprehensive understanding of atomic structure.
Chemistryimportant scientists and experiments that contributed to the current atomic model
ChemistryExplore the fundamentals of atomic structure, including subatomic particles, isotopes, relative atomic mass, and the periodic table. This summary provides key insights into atomic models, the Bohr model, and the significance of atomic numbers. Ideal for students preparing for exams in chemistry and physics.
ChemistryApp 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
I think itโs very much worth it and youโll 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 donโt get it!!! In the end I think itโs worth it ๐๐ โ ๏ธAlso DID I MENTION ITS FREEE YOU DONโT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYโ๏ธโ๏ธโ ๏ธ
Thomas R
iOS user
Knowunity is the BEST app Iโve 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 help๐ค๐ค
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.๐๐ฉท๐
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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 Iโve 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 itโs very much worth it and youโll 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 donโt get it!!! In the end I think itโs worth it ๐๐ โ ๏ธAlso DID I MENTION ITS FREEE YOU DONโT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYโ๏ธโ๏ธโ ๏ธ
Thomas R
iOS user
Knowunity is the BEST app Iโve 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 help๐ค๐ค
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.๐๐ฉท๐
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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 Iโve seen! Geometry too!
Paul T
iOS user
Chemistry
Oct 6, 2025
151
5 pages
The atomic structure and electron configuration of atoms, from early models to quantum mechanical understanding, forms the foundation of modern atomic theory. This comprehensive guide covers the evolution from Rutherford... Show more
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
This page delves deeper into the structure of electron energy levels in the quantum mechanical model, introducing the concept of electron configuration.
Principle Energy Levels are the main divisions of electron energy in an atom
Sublevels contain specific types of orbitals
Example The 2nd PEL has quantum number 2, so it contains 2 sublevels 2s and 2p.
Definition Electron configuration is a notation that shows how electrons are distributed in an atom's orbitals.
The Aufbau Principle guides the filling of orbitals
Highlight The order of filling follows a specific pattern 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, etc.
This page provides a foundation for understanding how to write and interpret electron configurations.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
This page focuses on the practical application of electron configuration principles, teaching how to write configurations and draw orbital diagrams.
Example For Lithium (Li), with 3 electrons 1sยฒ 2sยน
Orbital diagrams visually represent electron distribution
Highlight Hund's Rule states that electrons occupy orbitals of equal energy individually before pairing up.
Definition The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of quantum numbers. In practice, this means no more than two electrons can occupy the same orbital, and they must have opposite spins.
Examples are provided for elements like Lithium (Li), Beryllium (Be), and Boron (B), showing both electron configurations and orbital diagrams.
This page provides practical guidance for applying quantum mechanical principles to describe electron arrangements in atoms.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
This final page explores the concepts of valence electrons and kernel electrons, which are important for understanding chemical behavior and atomic structure.
Definition Valence electrons are the electrons in the outermost principle energy level of an atom.
Valence electrons are crucial for determining an atom's chemical properties and bonding behavior. They can be identified from the electron configuration or Bohr model diagram.
Definition Kernel electrons are all the electrons in the inner energy levels of an atom, excluding the valence electrons.
Kernel electrons typically do not participate in chemical reactions.
Example For Magnesium (Mg) 1sยฒ 2sยฒ 2pโถ 3sยฒ
- Valence electrons 2 (in 3s)
- Kernel electrons 10 (in 1s, 2s, and 2p)
The page includes examples of electron configurations and orbital diagrams for elements like Magnesium (Mg) and Calcium (Ca), highlighting their valence and kernel electrons.
Highlight Understanding valence electrons is crucial for predicting an element's chemical behavior and its position in the periodic table.
This page ties together the concepts of electron configuration with practical applications in chemistry and periodic trends.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Understanding electron configuration helps predict chemical behavior and element properties. This section demonstrates practical applications of electron configuration chart knowledge.
Example For Magnesium (Mg) 1sยฒ 2sยฒ 2pโถ 3sยฒ Shows 2 valence electrons in the outer shell
Vocabulary Valence electrons are those in the outermost principal energy level.
Definition Kernel electrons are all electrons except valence electrons.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The quantum mechanical model of atom represents a significant advancement in our understanding of atomic structure. This page introduces key concepts that differentiate this model from earlier atomic theories.
Definition The quantum mechanical model, also called the charge cloud or orbital model, describes electrons as existing in probability clouds around the nucleus rather than in fixed orbits.
The quantum model builds upon Bohr's concept of energy levels but incorporates important new ideas
Highlight The quantum model explains the bright line spectrum observed when excited electrons return to lower energy states, a phenomenon that supported Bohr's energy level concept.
Vocabulary Quantum - a discrete packet or bundle of energy, as proposed in Planck's theory
This model provides a more accurate and comprehensive description of atomic structure and electron behavior than previous models like the Bohr model or Rutherford atomic model.
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.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help โ all at your fingertips.
14
Smart Tools NEW
Transform this note into: โ 50+ Practice Questions โ Interactive Flashcards โ Full Mock Exam โ Essay Outlines
Basics of Atoms and theory including atom history.
Chemistryexamples of all Atomic Theories
ChemistryExplore the evolution of atomic models, including the Bohr model and the concept of atomic particles. This summary covers key concepts such as atomic structure, electronic configurations, isotopes, and the historical development of atomic theory. Ideal for students seeking a comprehensive understanding of atomic structure.
Chemistryimportant scientists and experiments that contributed to the current atomic model
ChemistryExplore the fundamentals of atomic structure, including subatomic particles, isotopes, relative atomic mass, and the periodic table. This summary provides key insights into atomic models, the Bohr model, and the significance of atomic numbers. Ideal for students preparing for exams in chemistry and physics.
ChemistryApp 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
I think itโs very much worth it and youโll 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 donโt get it!!! In the end I think itโs worth it ๐๐ โ ๏ธAlso DID I MENTION ITS FREEE YOU DONโT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYโ๏ธโ๏ธโ ๏ธ
Thomas R
iOS user
Knowunity is the BEST app Iโve 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 help๐ค๐ค
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.๐๐ฉท๐
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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 Iโve 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 itโs very much worth it and youโll 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 donโt get it!!! In the end I think itโs worth it ๐๐ โ ๏ธAlso DID I MENTION ITS FREEE YOU DONโT HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLYโ๏ธโ๏ธโ ๏ธ
Thomas R
iOS user
Knowunity is the BEST app Iโve 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 help๐ค๐ค
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.๐๐ฉท๐
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 ๐๐๐ฒ๐ค๐โจ๐๐ฎ
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 Iโve seen! Geometry too!
Paul T
iOS user
