Atomska zgradba je temelj za razumevanje kemije - od tega,... Show more
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Updated Apr 15, 2026
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Osnove atomske zgradbe in periodnega sistema
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Osnove atomske zgradbe
Atom je kot miniaturno osončje - v središču je jedro s protoni in nevtroni, okoli njega pa krožijo elektroni po določenih energijskih nivojih. Razporeditev elektronov določa, kako se element obnaša v kemijskih reakcijah.
Vrstno število (Z) pove število protonov in hkrati "identiteto" elementa. V nevtralnem atomu je število elektronov enako številu protonov. Masno število (A) pa je vsota protonov in nevtronov v jedru.
Izotopi so atomi istega elementa z različnim številom nevtronov. Na primer ogljik lahko ima 12, 13 ali 14 delcev v jedru - vsi so še vedno ogljik, ker imajo 6 protonov.
Zapomni si: Število protonov = vrstno število = "osebna izkaznica" elementa!
Elektronska konfiguracija in orbitale
Elektronska konfiguracija je način, kako zapišemo razporeditev elektronov po orbitalah. Orbitale so prostori, kjer najverjetneje najdemo elektron - vsaka sprejme največ 2 elektrona.
Poznamo štiri tipe orbital: s orbitale (krogla, 1 orbitala), p orbitale (ročke, 3 orbitale), d orbitale (5 orbital) in f orbitale (7 orbital). Elektroni najprej zapolnijo orbitale z nižjo energijo.
Tri zlata pravila zapolnjevanja: Aufbaujev princip (od najnižje energije navzgor), Pavlijevo načelo (v orbitali največ 2 elektrona z nasprotnim spinom) in Hundovo pravilo (v orbitalah z enako energijo najprej po eden elektron).
Pazi: 4s orbitala ima nižjo energijo kot 3d - to je pogosta past na testih!
Vrstni red zapolnjevanja orbital
Elektroni zapolnjujejo orbitale po določenem vrstnem redu: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p... Ta vrstni red si lahko zapomniš s pomočjo diagonalne sheme v periodnem sistemu.
Hundovo pravilo pomeni, da v treh p orbitalah elektroni najprej zapolnijo vsako z enim elektronom (↑↑↑), šele nato se začnejo pariti (↑↓↑↓↑↓). To je kot sedenje v avtobusu - najprej se posede vsak sam, šele nato skupaj.
Pavlijevo načelo zahteva, da sta elektrona v isti orbitali z nasprotnim spinom. To predstavimo s puščicama gor in dol (↑↓).
Nasvet: Pri reševanju nalog vedno najprej preštej elektrone, nato jih razporedi po orbitalah!
Povezava s periodnim sistemom
Perioda (vrstica) pove številko najvišje zasedene elektronske lupine. Elementi v 3. periodi imajo valenčne elektrone v 3. lupini .
Skupina (stolpec) za glavne skupine pove število valenčnih elektronov. 1. skupina ima 1 valenčni elektron, 17. skupina (halogeni) jih ima 7, 18. skupina (žlahtni plini) pa 8 (razen helij).
Periodni sistem je razdeljen na bloke: s-blok (skupini 1 in 2), p-blok , d-blok (prehodne kovine) in f-blok (lantanoidi in aktinoidi). Ime bloka pove, katera orbitala se zadnja polni.
Povezava: Elementi v isti skupini imajo podobne lastnosti, ker imajo enako število valenčnih elektronov!
Praktični primeri
Za klor razporedimo 17 elektronov: 1s²2s²2p⁶3s²3p⁵. Najvišja lupina je n=3 z 2+5=7 elektroni, zato je klor v 17. skupini.
Če imamo konfiguracijo 1s²2s²2p⁶3s², preštejemo elektrone: 2+2+6+2=12. To je magnezij (Mg), ki je v 3. periodi in 2. skupini (2 valenčna elektrona).
Za izotop ³⁹K: kalij ima Z=19, torej 19 protonov in 19 elektronov. Število nevtronov = A-Z = 39-19 = 20.
Trik: Za krajši zapis uporabi žlahtni plin iz prejšnje periode: Cl = [Ne]3s²3p⁵
Ioni in dodatni nasveti
Ioni nastanejo z oddajanjem ali sprejemanjem elektronov. Njihova elektronska konfiguracija se razlikuje od nevtralnega atoma - običajno dosežejo konfiguracijo najbližjega žlahtnega plina.
Masno število v zapisu izotopa je celo število, atomska masa v periodnem sistemu pa decimalno - to je povprečje mas vseh naravnih izotopov.
Pri ionih pazi: Na⁺ ima 11 protonov, a le 10 elektronov, zato je pozitiven. Cl⁻ ima 17 protonov in 18 elektronov, zato je negativen.
Za test: Z = št. protonov = št. elektronov (nevtralen atom), A = protoni + nevtroni, perioda = najvišja lupina, skupina = valenčni elektroni!
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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.
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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.
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Thomas R
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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.
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Xander S
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THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. 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
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Osnove atomske zgradbe in periodnega sistema
Atomska zgradba je temelj za razumevanje kemije - od tega, kako so elektroni razporejeni v atomu, je odvisno, kako se elementi obnašajo in povezujejo med seboj. Periodni sistem ni le tabela elementov, ampak pravi zemljevid, ki nam razkrije vzorce v... Show more
Osnove atomske zgradbe
Atom je kot miniaturno osončje - v središču je jedro s protoni in nevtroni, okoli njega pa krožijo elektroni po določenih energijskih nivojih. Razporeditev elektronov določa, kako se element obnaša v kemijskih reakcijah.
Vrstno število (Z) pove število protonov in hkrati "identiteto" elementa. V nevtralnem atomu je število elektronov enako številu protonov. Masno število (A) pa je vsota protonov in nevtronov v jedru.
Izotopi so atomi istega elementa z različnim številom nevtronov. Na primer ogljik lahko ima 12, 13 ali 14 delcev v jedru - vsi so še vedno ogljik, ker imajo 6 protonov.
Zapomni si: Število protonov = vrstno število = "osebna izkaznica" elementa!
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Elektronska konfiguracija in orbitale
Elektronska konfiguracija je način, kako zapišemo razporeditev elektronov po orbitalah. Orbitale so prostori, kjer najverjetneje najdemo elektron - vsaka sprejme največ 2 elektrona.
Poznamo štiri tipe orbital: s orbitale (krogla, 1 orbitala), p orbitale (ročke, 3 orbitale), d orbitale (5 orbital) in f orbitale (7 orbital). Elektroni najprej zapolnijo orbitale z nižjo energijo.
Tri zlata pravila zapolnjevanja: Aufbaujev princip (od najnižje energije navzgor), Pavlijevo načelo (v orbitali največ 2 elektrona z nasprotnim spinom) in Hundovo pravilo (v orbitalah z enako energijo najprej po eden elektron).
Pazi: 4s orbitala ima nižjo energijo kot 3d - to je pogosta past na testih!
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Vrstni red zapolnjevanja orbital
Elektroni zapolnjujejo orbitale po določenem vrstnem redu: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p... Ta vrstni red si lahko zapomniš s pomočjo diagonalne sheme v periodnem sistemu.
Hundovo pravilo pomeni, da v treh p orbitalah elektroni najprej zapolnijo vsako z enim elektronom (↑↑↑), šele nato se začnejo pariti (↑↓↑↓↑↓). To je kot sedenje v avtobusu - najprej se posede vsak sam, šele nato skupaj.
Pavlijevo načelo zahteva, da sta elektrona v isti orbitali z nasprotnim spinom. To predstavimo s puščicama gor in dol (↑↓).
Nasvet: Pri reševanju nalog vedno najprej preštej elektrone, nato jih razporedi po orbitalah!
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Povezava s periodnim sistemom
Perioda (vrstica) pove številko najvišje zasedene elektronske lupine. Elementi v 3. periodi imajo valenčne elektrone v 3. lupini .
Skupina (stolpec) za glavne skupine pove število valenčnih elektronov. 1. skupina ima 1 valenčni elektron, 17. skupina (halogeni) jih ima 7, 18. skupina (žlahtni plini) pa 8 (razen helij).
Periodni sistem je razdeljen na bloke: s-blok (skupini 1 in 2), p-blok , d-blok (prehodne kovine) in f-blok (lantanoidi in aktinoidi). Ime bloka pove, katera orbitala se zadnja polni.
Povezava: Elementi v isti skupini imajo podobne lastnosti, ker imajo enako število valenčnih elektronov!
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Praktični primeri
Za klor razporedimo 17 elektronov: 1s²2s²2p⁶3s²3p⁵. Najvišja lupina je n=3 z 2+5=7 elektroni, zato je klor v 17. skupini.
Če imamo konfiguracijo 1s²2s²2p⁶3s², preštejemo elektrone: 2+2+6+2=12. To je magnezij (Mg), ki je v 3. periodi in 2. skupini (2 valenčna elektrona).
Za izotop ³⁹K: kalij ima Z=19, torej 19 protonov in 19 elektronov. Število nevtronov = A-Z = 39-19 = 20.
Trik: Za krajši zapis uporabi žlahtni plin iz prejšnje periode: Cl = [Ne]3s²3p⁵
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Ioni in dodatni nasveti
Ioni nastanejo z oddajanjem ali sprejemanjem elektronov. Njihova elektronska konfiguracija se razlikuje od nevtralnega atoma - običajno dosežejo konfiguracijo najbližjega žlahtnega plina.
Masno število v zapisu izotopa je celo število, atomska masa v periodnem sistemu pa decimalno - to je povprečje mas vseh naravnih izotopov.
Pri ionih pazi: Na⁺ ima 11 protonov, a le 10 elektronov, zato je pozitiven. Cl⁻ ima 17 protonov in 18 elektronov, zato je negativen.
Za test: Z = št. protonov = št. elektronov (nevtralen atom), A = protoni + nevtroni, perioda = najvišja lupina, skupina = valenčni elektroni!
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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
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 Knowunity AI. 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 Knowunity AI. 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