The discovery of hafnium, element number 72, provided a controversial episode in chemistry. G. Urbain, a French chemist, claimed in 1911 to have isolated an element number 72 from a sample of rare earth (elements 58–71) compounds. However, Niels Bohr believed that hafnium was more likely to be found along with zirconium than with the rare earths. D. Coster and G. von Hevesy, working in Bohr's laboratory in Copenhagen, showed in 1922 that element 72 was present in a sample of Norwegian zircon, an ore of zirconium. (The name hafnium comes from the Latin name for Copenhagen, Hafnia). (a) How would you use electron configuration arguments to justify Bohr's prediction?

Video transcript

Hello everyone in this video, we're trying to find the electron configuration of element number 104. However, this last section of the puree table is said to be gone. So this right here is not going to be available for us to use and we need to figure out the electron configuration. So If we zoom in to prepare our table, we can see that 104 is actually going to be right over here. But like I said, this part is not available to us. So how do we suffer this? Well, the closest noble gas that is still within the the available periodic table is going to be this right here because as we know this whole column right here, that's going to be all of our noble gasses. Alright, so our N is going to be the Noble guests that we're going to use for the electric configuration of element number 14. So, we'll put that in brackets. Let's go down just a little bit. All right, So we have our n in brackets. Alright, so RN has atomic number of 86. If we're looking for 104, let's go ahead and subtract that. So, 104 minus We're going to get 18. So 18 is a number of remaining electrons that we need to consider. Alright, so, as you can see after this element here, if we're reading or continuing the electron configuration, we grow through the US F and D orbital. So considering our s orbital, we know that that can only contain two electrons. As for the f orbital, It can contain four electrons And then the D can contain 10 electrons. So of course we're going to need a total of 18 because that's our difference. And if we add these first two, that's going to be 16 electrons, of course we need two more. So we'll just take two from this D orbital here. So if we were to continue this election configuration for the S F and D orbital, then it would be, let's see here we are 1st, 2nd, 3rd 4 here, six and seven. So Using this snowball gas, then we'll be onto the 7th row. So that's going to be 7 S2, Then five F 14. So we have that too. Yes, 14 from the f. And then we need to from the deep, So that's going to be six D two And this is going to be the electron configuration of element number 104.