Write the condensed electron configurations for the following atoms and indicate how many unpaired electrons each has: (f) Lu.

Video transcript

everyone in this example. We need to choose the correct shorthand electron configuration and number of unpaid electrons for the atom selenium. So we want to recall that the shorthand configuration is also known as our noble gas configuration for our given atom. And so we would recognize that on our periodic tables. Selenium is located in Group six A. Which falls across period four of our periodic table. So we want to find the noble gas that comes before period four on the periodic table and that would correspond to noble gas argon. So we would have argon in brackets to begin our configuration and we would recognize that moving on into our fourth period, we need to fill up the lowest energy sub level in order to honor our out about principle. So we would have, because we're in the fourth period of our periodic tables, the fourth energy level, we would be at the S sub level because we recall that's the smallest sub level and we should recall that it holds a maximum of two electrons. So we would have for us to to begin our next part of our configuration. Then we would move into our D block, which we recall is our transition metal section of our periodic table. And we should recall that at the fourth period. The D block begins at the third energy level. So we would have three D and we want to fully fill up this sub level. So we would recall that the D block has a total of five orbital's which can hold a maximum of 10 electrons. So we would have three D 10 in the exponent because we want to fully fill up this sub level. Moving on into our next sub level which would be our piece of level which also begins at the fourth energy level since we are on the fourth period of our periodic table. So we would have four P. We should recall that R p sub level can hold a maximum or has a maximum of three orbital's so we can represent those orbital's as these lines here and to land on our adam selenium within our P block, we would count a total of four units for us to land on our atoms selenium. So we would have an exponent of four in our configuration. And again it has a maximum or the p block has a maximum of three orbital's and so that can hold a maximum of six electrons. However, in our exponent here, we've only filled in four electrons since we counted four units to land on our adam selenium. So honoring our poly exclusion principle, we're going to fill in these electrons in each orbital one by one. So we would have 123 and then we would pair them up by the opposite spin. So for our fourth electron we're going to pair it up in this first orbital with the opposite spin for our total of four electrons. And as you can see, we're left with two unpaid electrons here and this is in our p block. So to make sure that we have the proper configuration, we want to make sure that we have it listed in order of ascending energy levels. So we would actually reframe our configuration so that we have argon because we want it listed in order of ascending energy levels. We're going to begin with the lowest energy level which is in the D block being at three D 10. So the third energy level, then we move up into our next smallest sub level, which is the S sub level because we would recognize that the S sub level can only hold a maximum of two electrons. So we would list for us to next and then to complete our configuration, we have four P four last because it's at the fourth energy level and it's a larger sub level than the S sub level because it can hold a maximum of six electrons. But in this case we only filled in four for adam selenium. And so our final answer is to complete this example is going to be this configuration here as well as our two unpaid electrons in our P block that we determined for our configuration of selenium. So this completes this example. If you have any questions, please leave them down below. Otherwise, I will see everyone in the next practice video