Chemistry, asked by pranshu2391, 10 months ago

Why do we write 3d5 4s1 in chromium and not 4s1 3d5. why 3d5 before 4s1

Answers

Answered by danieltoman

You need to fill up the closer shells to the nucleus first! You are writing them in the way that they are filled up first, and they would fill up the closer shells completely, before they fill up the one next. :)

pranshu2391: but by n+l rule 4s has less energy. so it should fill first

danieltoman: explain, as i have never come across it before, what the n+1 rule is

pranshu2391: any reason for that

danieltoman: i never had to learn it for my exams

pranshu2391: it is rule to determine energy level

danieltoman: but electrons are negatively charged

pranshu2391: if n+l is equal then only n is seen

pranshu2391: neg ??

pranshu2391: what is that for?

pranshu2391: there is nothing about electron charge in n+l rule

Answered by bhaveshvk18

hey

This is because of Aufbau's principle. According to Aufbau's principle lower energy shell should be filled first and then it should enter higher energy shell. Thus we write 4s before 3d

pranshu2391: we write 3d first

pranshu2391: see periodic table

bhaveshvk18: nope...we 4s = 4 + 0 = 4 3d = 3 + 2 = 5 so we write 4s first

bhaveshvk18: better u check it

pranshu2391: still

pranshu2391: see periodic table

pranshu2391: i asked so because of that only

bhaveshvk18: lol...leave it..

pranshu2391: kyu

bhaveshvk18: better ask ur teacher

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Why do we write 3d5 4s1 in chromium and not 4s1 3d5. why 3d5 before 4s1​

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Why do we write 3d5 4s1 in chromium and not 4s1 3d5. why 3d5 before 4s1