00:01
So for this question, we're asked to write the electron configurations for the following elements.
00:08
So first we'll start with cesium, which is number 55, on the periodic table.
00:15
If we look at the rows, it's in row six.
00:22
If we go to the previous noble gas, it's xenon.
00:26
So the noble gas core is xenon.
00:31
And then it's in the sixth row.
00:35
Remember that these first two columns are the s group.
00:40
The transition metals are in the d block, and then these last six are the p block, and then these two rows down here are in the f block.
00:51
So if we look at cesium, it's going to be in 6s, and we have one electron in the 6s block, so it'll be xenon 6s1.
01:03
Next, we'll go to nickel, which is number 28, to transition metal.
01:09
If we go to the preceding noble gas, it's going to be argon, so it has a noble gas core of argon.
01:16
Then we look at the row that it is in.
01:18
We have 4s2, right? we're in row 4, so we have 2 in the s block.
01:25
And then we go to the d block.
01:27
Remember, the d block is always one less than the row it's in.
01:31
So since it's in row 4, it's going to be the 3d block.
01:35
And then we count electrons one, two, three, four, five, six, seven, eight.
01:40
So we have eight electrons in the three d block.
01:44
Next we'll go to selenium.
01:49
It's in the same row as nickel.
01:54
So selenium is in the same row as nickel.
01:56
It has the same noble gas core argon.
02:05
And then we're in row four.
02:07
So we have four s, which is completely filled.
02:10
So it's fours two.
02:11
Then we have the d block, the three d block, which is completely filled so it's going to be 3d10 and then we're in the 4p block and we have 1, 2, 3, 4 electrons in the 4p block.
02:25
Next we'll go to cadmium which is a transition metal in row 5...