Predict the number of unpaired electrons for each of the following.

(c) Mn3+

(d) Cr2+

Video transcript

Welcome back everyone. How many unpaired electrons are expected for the following ions? Let's begin with the first species and we're given iron two plus what we want to do to begin with is just write down the electron configuration for neutral iron. And if we use the periodic table, we end up with the following. Specifically, we want to use the noble gas notation. We're going to begin with organ and we're going to consider the next shell which essentially contains 42, followed by three D six. Let's recall that we want to remove the electrons from the highest energy level whenever we are producing an ion. So for iron two plus, we need to remove the two electrons from the highest principle quantum number level, which is four, right? If we remove the two S electrons, we end up with organ 3d 6. This tells us the electron configuration. And now we simply want to draw five D orbitals, right? Because there are always five D orbitals. And we want to add those six electrons based on the hunt's rule. First of all, we're adding single electrons to each orbital until we fill each orbital partially and now we have one extra electron, so we start pairing. And therefore, if we look at the given diagram, we have 1234 unpaired electrons. If we move on to Cobalt three plus, we will once again consider the electron configuration of neutral cobalt to begin with. Based on the periodic table, we are going to obtain the configuration of organ followed by four S 2 3d 7. And now, if we want to get Cobalt three plus, we want to remove the two electrons from the highest energy level and one more from the 3d shell because it's three plus. So we are removing three electrons. Now, what does that mean? Well, essentially the electron configuration will be the same as iron two plus. So they are isoelectronic we in the six, which will essentially give us the same diagram. And therefore, we will also have four unpaired electrons. So both species iron two plus and cobalt three plus, they would have four unpaired electrons each. Thank you for watching.