You should be able to click on it and watch the whole thing, but i want you to see this property that most people don’t know exists. Now let me back up before i sort of have you watched a little segment of this video, but remember: electrons have magnetic moments and they’re, either always in one direction or another, that is, they always have a magnetic field going in one direction or they have the Magnetic field going in another direction and there’s no in betweens it’s not like a regular magnet that if you’re holding a bar magnet – and you want to sort of stop the attraction or the repulsion, you can just take the bar magnet and turn it sideways. In other words, if i have a magnet like this – and this is north – and this is south down here and then i have another north and south magnet there’s a force of attraction there. If i turn it the other way, south and north, like that, then there’s a force of repulsion, but i can take a regular magnet and turn it sideways and go north and south and that effectively has no attraction or repulsion for that magnetic field. So here’s the thing electrons aren’t like that they’re always pointed one way or the other so they’re, always either repelled by a magnetic field or always attracted to it. You might not think of water as being magnetic, but it is, and so are graphite, aluminum and glass.
This is a new and different category of magnetism, called either para or diamagnetism, and it’s different from the magnetism that you’re used to you’re, probably already familiar with ferromagnetism pharaoh means iron. An unmagnetized piece of iron or nickel or cobalt becomes a magnet in the presence of a magnetic field. The effect is strong and lasts even after the magnet is removed. Paramagnetism is a similar effect, except that it’s much weaker and temporary aluminum is a good example of a paramagnet, and so is oxygen which is attracted to magnets. Here i have a few milliliters of liquid oxygen, which sticks to the magnet i’ll, explain why later gadolinium oxide and cupric sulfate are good examples of paramagnetic substances. Cupric sulfate is a salt that can be picked up by a magnet. Diamagnetic materials are exactly the opposite of paramagnetic, they are always repulsed, they would rather die than being a magnetic field. An important example of a diamagnetic material is graphite. This specially made pyrolytic graphite is repelled by a magnetic field. Don’T be confused. This is not static. Electricity or eddy currents, graphite is repelled by a magnet, always both by the north and south end. Pyrolytic graphite is a grown crystal of flat carbon layers, which maximizes the diamagnetic effect. Of course, the best diamagnets are superconductors, which at low temperatures, provide exact, opposite repulsion to whatever magnetic field is present when they’re chilled they are perfect. Diamagnets, the most famous and powerful diamagnetic is bismuth element number 83 on the periodic table.
The bismuth powered boat sails toward the weaker magnetic fields, so to get a better understanding of why different elements are either paramagnetic or diamagnetic. We have to actually look at their orbital diagram, so we’ll begin with writing their electron configurations, and so we find aluminum aluminums here on the periodic table and so it’s going to have an electron configuration that goes with a neon core and then 3s2 and then 3p1. So 3s2 p, 3p1. Now in the orbital diagram, oh and i have a core right neon. But if i write the orbital diagram for the valence electrons, because this is what’s going to matter – there’s, 3s and 3p – and i have electrons going like this – and i have one electron going like that now aluminum was one of those elements that he showed was diamagnetic. He also showed carbon was diamagnetic, but actually that’s trickier to answer that question, because carbon is actually bonded to other carbon atoms in graphite and we’ll cover that in about a chapter and a half okay it’s about halfway through the chapter on bonding and orbital theory, anyways Unpaired electrons unpaired and since it’s unpaired, its magnetic field is not cancelled out, so aluminum right will be always attracted to a magnetic field. Remember the magnetic moment of an electron is always either one way or the other, but if i hold a magnetic field to it, it orients in such a way that it’s attracted to the magnetic field and then is drawn towards it.
Now, if we look at zinc, two plus and i haven’t done any ions, so i thought i would do the electron configurations ions here. We need to go to the periodic and what we’ll do is say: zinc is here and so we’re gon na have a core of argon and then we’re going to have 4s2 and then 3d10. So we’ll go ahead and fill that out so for zinc. The element it’s 4s2, with the core right 3d10. Now the transition metals, when you make ions out of them, in fact any element when you make an ion out of it, you have to take the highest energy level electrons that are available, so zinc, 2 plus becomes 3 d 10 in its electron configuration. So if we write the orbital diagram for 3d 10, i have one two, three, four, five, six, seven, eight nine ten like this. All the electrons are paired. So there isn’t any situation where this magnetic moment can be a tr, because the because they’re paired up and there’s no single unpaired electron there’s no way to stick zinc, two plus into a magnetic field and have it be attracted because you’re either going to be attracted To one and repelled by the other or repelled by one and attracted to the other, and so diamagnetic substances have paired electrons, and i know that sounds horrible and paramagnetic substances have unpaired electrons, but paramagnetic is p a r, a and then magnetic right.
What about copper? Two plus right, so if i take copper, two plus i have to do the electron configuration for copper first and i’ll. Do the electron configuration for the ion. So copper is here in the periodic table right, so it’s going to get it’s next to zinc right. So it’s going to be argon as its core and then the outermost shell will be 4s2 and then 3d9, so i’ll write, copper, 4 s, 2, 3 d. 9.. Now, if you’re, quick and remember this, this is actually one of the ones that has an exception. So it’s forest one 3d 10, but it won’t matter for what we’re doing when i go to make the copper two plus ion, then what happens is i have to take two electrons off and my electron configuration at least the outermost part of it is going to Be 3d9: i still have that core of argon in the center, but now i’ve taken off the 4s electrons. So that means my electron configuration would look like this oops. Sorry i’ll. Do it the way i’m supposed to put them in one at a time right? There’S. 5. 6. 7. 8. 9.. I have this unpaired electron, so this will be paramagnetic by the way in that video. He goes on to show a number of other examples, and he goes through the explanations i think for several of these. I didn’t pay attention to all of it, but i think he does do aluminum because that’s one of the first examples he does and he does perhaps and i didn’t again i haven’t watched it in a while.
I don’t remember whether or not he talked about oxygen. Oxygen is also one of those atoms that we’ll cover when we start talking about bonding and orbital theory. Okay, so paramagnetic right means it’s attracted to a magnetic field, and diamagnetic means it would rather die than be in a magnetic field. That was the way he said it right, but it’s repelled by a magnetic field and then, in order to be attracted, you have to have unpaired electrons, and that means you can orient, the atom can be oriented or the electrons in the atom can be oriented in Such a way that it’s attracted to the magnetic field that’s around it now i should point out he did talk about ferromagnetic and ferromagnetic is like the normal magnetism that you see and what happens in ferromagnetism that’s different than paramagnetism is the magnetic moments of the aligned Electrons stay after the magnets removed and that’s how they become magnetized. You can actually demagnetize if anybody’s ever worked in a surgical setting, stainless steel equipment can sometimes get magnetized and they have to demagnetize it and the way they do that is, they actually have this little hammer and they hit it with the hammer and that imparts enough Energy to scramble the orientations of the electrons and then it for all practical purposes, no longer magnetic, unless, of course, you bring in the presence of another magnet okay, so that’s paramagnet the magnetism sort of explained based on the orbital diagrams in order to get the orbital Diagrams, of course, we had to do the electron configurations.
Ions can be done just like atoms. You just have to subtract the appropriate number of electrons from the highest energy level of the atom um. I did want to point out one more thing: there’s. Actually, a couple extra slide examples of cations being formed like the two plus and the three plus ions for iron for transition, metals and another, a couple of slides explaining paramagnetism and diamagnetism, giving other examples.viipXUxQIk0