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Hi there.
00:02
In this question, we are asked for the electron configuration for a neutral atom of krypton.
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So krypton has the symbol kr, and looking at the periodic table, we see that its atomic number is 36.
00:18
That tells us that it has 36 protons, and since it's a neutral atom and protons are positively charged, it must also have 36 negative particles, or in other words, 36 electrons.
00:31
Electrons.
00:34
All right, so we need to write the electron configuration for those 36 electrons.
00:39
And remember, an electron configuration shows where the electrons are located in the different energy levels and subshells.
00:47
And to determine where to place these, we need to follow the aufbau principle.
00:55
The aufbau principle tells us that electrons are placed into orbitals in order of increasing energy.
01:25
So what that means is the first electrons go into the lowest energy level and we build from there.
01:34
Okay so the lowest energy orbital is in the first energy level and it's the s -shaped orbital and s orbitals can hold a maximum of two electrons so our first two electrons go into the 1s.
01:48
That s orbital is the only sub level in the first energy level so where we need to go next is the second energy level and and again, we have an s orbital as the lowest energy orbital there.
02:01
And s's can hold two.
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But in the second energy level, we also have a p sub level.
02:09
And p orbitals, there are three of those.
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And we place two electrons in each one for a total of six.
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So we write 2p6, meaning there are six electrons in those two p orbitals...