1
00:00:03,609 --> 00:00:07,530
Hello class in this video I'm going to teach you how to get the electronic

2
00:00:07,530 --> 00:00:12,830
configuration for some elements depending on the different energy of the

3
00:00:12,830 --> 00:00:18,449
orbitals and how to write it. So let's start with something simple okay let's

4
00:00:18,449 --> 00:00:26,550
start for example with this element phosphorus okay phosphorus you can

5
00:00:26,550 --> 00:00:32,969
look it up in the periodic table has an atomic number of 15 which means

6
00:00:32,969 --> 00:00:45,399
that its nucleus has 15 protons and it has 15 electrons in the cell that we

7
00:00:45,399 --> 00:00:49,840
place in the different orbitals. So we are going to start counting electrons.

8
00:00:49,840 --> 00:00:53,380
Remember we are going to represent electrons like these little arrows

9
00:00:53,380 --> 00:00:57,979
upwards and downwards and we're going to place them here in these boxes that are

10
00:00:57,979 --> 00:01:03,840
the orbitals. So we start here with 1s, one, two electrons. So the first two

11
00:01:03,840 --> 00:01:09,359
electrons of this 15 go to the 1s orbital, we write that

12
00:01:09,359 --> 00:01:22,560
information as this, we go on, more electrons here, more here, okay let's

13
00:01:22,560 --> 00:01:28,439
count how many we have for the moment, it was 2 and 2, 4 and 6 more here, that is

14
00:01:28,439 --> 00:01:37,739
10 we are now we have 10 electrons we indicate the 2s of electrons like this and the 2p electrons

15
00:01:37,739 --> 00:01:43,540
we indicate like this still five electrons to go so i need to place five electrons more

16
00:01:43,540 --> 00:01:54,620
so two go here i have 12 right now and i have three left one two and three and we're done

17
00:01:54,620 --> 00:02:02,060
we finish how do we write this so in the 3s orbital i have two electrons and then in the

18
00:02:02,060 --> 00:02:10,060
three p orbitals i have three electrons this is the electronic configuration for phosphorus

19
00:02:12,060 --> 00:02:20,300
okay let's go with another element a little more with more electrons like

20
00:02:20,300 --> 00:02:29,740
ion okay ion has an atomic number of 26 meaning that i have to place 26 electrons in its orbitals

21
00:02:30,699 --> 00:02:40,580
i'm going to use this i have already placed 15 so i still have 11 electrons to go

22
00:02:42,099 --> 00:02:48,419
okay so this is 12 as you can see here i have three here not to place three more

23
00:02:50,990 --> 00:02:59,789
okay so it's 3p6 right now i have 18 electrons still eight electrons to place and then

24
00:03:00,509 --> 00:03:07,150
there is a significant jump instead of filling the 3d after the 3p 4s

25
00:03:08,349 --> 00:03:16,590
go first because it has less energy you can see it's it's down in the diagram in the diagram

26
00:03:16,590 --> 00:03:27,229
it's below 3d so it's 4s2 okay and we have a still let's say i say this was 10

27
00:03:28,509 --> 00:03:35,150
still six electrons to uh yes six select six electrons electrons to go and this is

28
00:03:35,150 --> 00:03:45,710
electrons are going to go here one two three four five and six and they represented like this

29
00:03:46,590 --> 00:03:55,229
three six okay so to write the electronic configuration of an element i only need to

30
00:03:55,229 --> 00:04:02,430
know how many electrons the element has and how to distribute this and what is the

31
00:04:02,990 --> 00:04:06,909
difference energy of the orbitals goodbye