1 00:00:06,100 --> 00:00:07,840 We are going to try and do an experiment today. It is called 2 00:00:07,840 --> 00:00:11,549 the ‘gallium beating heart’. So it is quite a cool experiment, 3 00:00:11,549 --> 00:00:14,969 you take some molten gallium and then you submerge it or 4 00:00:14,969 --> 00:00:18,840 you put it underneath a layer of sulphuric acid. The sulphuric 5 00:00:18,840 --> 00:00:22,740 acid reacts with the gallium to form gallium sulphate and it 6 00:00:22,740 --> 00:00:27,190 changes the surface tension, so it all pulls up into a ball and 7 00:00:27,190 --> 00:00:31,940 then relaxes and there is this really neat oscillating reaction 8 00:00:31,940 --> 00:00:34,840 where you get sulphate on the surface or no sulphate on the 9 00:00:34,840 --> 00:00:38,989 surface. So you see big changes in surface tension and the 10 00:00:38,989 --> 00:00:41,999 piece of gallium is seen to beat like a heart so we thought we 11 00:00:41,999 --> 00:00:44,089 would try that today with a bit of gallium which I am trying to 12 00:00:44,089 --> 00:00:45,309 melt in my hand right now. 13 00:00:45,309 --> 00:00:49,479 Many years ago, a professor bet me a hundred pounds, when 14 00:00:49,479 --> 00:00:52,659 a hundred pounds was a lot of money, that the melting point 15 00:00:52,659 --> 00:00:55,949 of gallium was lower than that of caesium and I said it was 16 00:00:55,949 --> 00:00:59,760 the other way round, but I was not courageous enough to 17 00:00:59,760 --> 00:01:02,519 take up the bet or now I would be rich. 18 00:01:02,519 --> 00:01:06,570 So this is a small nugget of gallium and as you can see if I 19 00:01:06,570 --> 00:01:10,060 tap it on the hot plate it is real metal so now we are going to 20 00:01:10,060 --> 00:01:13,189 try and melt it, hopefully in my hand. 21 00:01:13,189 --> 00:01:19,009 In my first video about gallium, I said that it was not a very 22 00:01:19,009 --> 00:01:23,850 interesting element with not much, many applications and we 23 00:01:23,850 --> 00:01:28,189 have had emails from people who were outraged. There is 24 00:01:28,189 --> 00:01:32,380 one email from a gentleman in America whose company 25 00:01:32,380 --> 00:01:35,859 makes tonnes of gallium salts that have quite important 26 00:01:35,859 --> 00:01:41,350 applications and of course gallium is particularly important in 27 00:01:41,350 --> 00:01:48,350 new generation of compounds, so-called semi-conductors, that are used in the electronics industry. 28 00:01:48,740 --> 00:01:52,429 So if I stand and hold it for long enough, in theory, the 29 00:01:52,429 --> 00:01:54,240 temperature should come from my hand, the heat should 30 00:01:54,240 --> 00:01:56,840 come from my hand, so it should melt the gallium and then 31 00:01:56,840 --> 00:02:00,039 eventually we should have a small amount of liquid. So 32 00:02:00,039 --> 00:02:04,179 gallium, you can form an amalgam with this material, with all 33 00:02:04,179 --> 00:02:07,469 sorts of different materials like indium and tin. And in fact 34 00:02:07,469 --> 00:02:11,500 indium, tin and gallium is used as the material inside many, 35 00:02:11,500 --> 00:02:15,010 many thermometers which are used in the medical industry 36 00:02:15,010 --> 00:02:18,290 because it is not as toxic as mercury which was traditionally 37 00:02:18,290 --> 00:02:21,790 used. You may have heard of Mendeleev. He was the guy that 38 00:02:21,790 --> 00:02:25,390 sort of conceived or brought together the periodic table and 39 00:02:25,390 --> 00:02:28,250 at the time that he did this at about 1870, gallium hadn’t 40 00:02:28,250 --> 00:02:31,670 been discovered, so he predicted its chemical and physical 41 00:02:31,670 --> 00:02:35,230 properties and he called it eka-aluminium, approximately 5 42 00:02:35,230 --> 00:02:38,960 years after that it was found using a spectroscope. So now 43 00:02:38,960 --> 00:02:43,340 we see it is melted, it looks just like a little ball of mercury 44 00:02:43,340 --> 00:02:47,240 rolling around on my hand. You can see the thick skin that 45 00:02:47,240 --> 00:02:51,170 has developed the surface tension causing it to form such a 46 00:02:51,170 --> 00:02:55,730 beautiful bulb. We are going to take out our molten gallium 47 00:02:55,730 --> 00:03:00,760 and we are going to put it under a layer of dilute sulphuric 48 00:03:00,760 --> 00:03:03,420 acid, about the same strength as battery acid, so now we are 49 00:03:03,420 --> 00:03:06,980 going to make the acid. And to do that we are going to dilute 50 00:03:06,980 --> 00:03:10,140 concentrated sulphuric acid with water. Now it is always 51 00:03:10,140 --> 00:03:13,540 important to remember that when you dilute acid you always 52 00:03:13,540 --> 00:03:17,560 put acid into water because the reaction can be exothermic 53 00:03:17,560 --> 00:03:21,200 and we want to dissipate the heat in the water so that it does 54 00:03:21,200 --> 00:03:26,100 not squirt up on our faces. The water was room temperature, 55 00:03:26,100 --> 00:03:29,010 but if I hold the measuring cylinder here it is actually very 56 00:03:29,010 --> 00:03:33,090 hot, it is maybe 40, 50, 60oC. So now before we do our 57 00:03:33,090 --> 00:03:36,760 experiment we have got to allow it to cool. We do that by 58 00:03:36,760 --> 00:03:39,940 simply running cold water outside the tube. 59 00:03:39,940 --> 00:03:43,070 So this is the gallium that we melted on our hand, now let’s 60 00:03:43,070 --> 00:03:47,730 see what happens when we add the sulphuric acid. Wow, did 61 00:03:47,730 --> 00:03:48,940 you see that? 62 00:03:48,940 --> 00:03:51,340 I did. What happened? 63 00:03:51,340 --> 00:03:55,540 So the shape of the ball or the lump of gallium has changed, 64 00:03:55,540 --> 00:03:57,460 because we’ve changed it surface properties, we’ve 65 00:03:57,460 --> 00:04:00,040 made gallium sulphate on the surface. The surface tension 66 00:04:00,040 --> 00:04:04,090 has got higher and it has pulled up into a nice ball, ok. So 67 00:04:04,090 --> 00:04:07,280 that’s the first step of the beating heart. What we’ve seen is 68 00:04:07,280 --> 00:04:10,380 the gallium which was relaxed flat on the surface has pulled 69 00:04:10,380 --> 00:04:15,240 up really quite sharply and that is the first stage, or the in- 70 00:04:15,240 --> 00:04:19,289 beat of the heart, now we’ve got to make the heart relax. So 71 00:04:19,289 --> 00:04:23,030 what we are going to do is use dichromate. Dichromate is a 72 00:04:23,030 --> 00:04:26,070 fantastic oxidant and we are going to put a small amount of it 73 00:04:26,070 --> 00:04:26,940 in and see what happens. 74 00:04:26,940 --> 00:04:33,940 So gallium, I realise now is named after France. It was 75 00:04:34,530 --> 00:04:41,530 discovered by a Frenchman and its name comes from the old 76 00:04:41,630 --> 00:04:48,630 name for France, Gaul. 77 00:04:50,460 --> 00:04:53,540 So what we are doing in this experiment, we are changing the 78 00:04:53,540 --> 00:04:57,100 surface tension of the gallium, so these are the forces that 79 00:04:57,100 --> 00:05:03,090 hold the liquid into a ball or allow it to wet and flatten on the 80 00:05:03,090 --> 00:05:08,790 surface. So when the gallium is naked, ok? It’s actually quite 81 00:05:08,790 --> 00:05:12,150 flat and it wets the surface. But when we put it under 82 00:05:12,150 --> 00:05:15,460 sulphuric acid we form gallium sulphate on the surface, this 83 00:05:15,460 --> 00:05:18,970 increases the surface tension and then pulls the gallium so it 84 00:05:18,970 --> 00:05:22,370 is in a nice proud ball. What we then do is we dribble a small 85 00:05:22,370 --> 00:05:25,190 amount of dichromate solution in, which removes the 86 00:05:25,190 --> 00:05:27,630 sulphate from the surface and allows the gallium to go flat, 87 00:05:27,630 --> 00:05:32,060 and if we add the required amount of dichromate to the 88 00:05:32,060 --> 00:05:34,810 amount of acid then we can get the ball to flatten and come 89 00:05:34,810 --> 00:05:38,139 back up, flatten and come back up, so it looks like a beating 90 00:05:38,139 --> 00:05:38,980 heart. 91 00:05:38,980 --> 00:05:42,210 At the moment we are really quite excited at Nottingham 92 00:05:42,210 --> 00:05:47,250 because Steve Liddle, my periodic videos colleague, has made 93 00:05:47,250 --> 00:05:53,800 a new compound in which he has got an atom of uranium to 94 00:05:53,800 --> 00:05:58,400 bond to an atom of gallium and this is exciting because this is 95 00:05:58,400 --> 00:06:01,870 the first time that chemists have ever seen a bond between 96 00:06:01,870 --> 00:06:02,710 these two atoms. 97 00:06:02,710 --> 00:06:08,210 It sort of turns a terracottery colour, it is really a deep orangey 98 00:06:08,210 --> 00:06:11,180 brown, it is a bit like brick dust actually. 99 00:06:11,180 --> 00:06:15,280 Of course they are not naked uranium and naked gallium but 100 00:06:15,280 --> 00:06:19,840 each of them have other things bonded to them but it is the 101 00:06:19,840 --> 00:06:23,490 first time that anybody has seen a gallium-uranium bond. 102 00:06:23,490 --> 00:06:27,610 It was one of those great moments you know, being a 103 00:06:27,610 --> 00:06:30,790 chemist is like being on a rollercoaster, you have some days 104 00:06:30,790 --> 00:06:33,930 when you wonder why am I doing this? And you have 105 00:06:33,930 --> 00:06:38,330 fantastic days where you totally remember why you are doing 106 00:06:38,330 --> 00:06:39,530 this. Because it is to be the first, to be the first person who 107 00:06:39,530 --> 00:06:40,120 has ever made this particular, you know filling the gap, 108 00:06:40,120 --> 00:06:44,950 whatever it is. It is a real thrill when you are the first person 109 00:06:44,950 --> 00:06:49,210 to make a compound that does not exist out in the galaxy 110 00:06:49,210 --> 00:06:52,970 and space, it has never existed on our planet before but now 111 00:06:52,970 --> 00:06:56,550 we have made it for the first time. That’s a really good thing 112 00:06:56,550 --> 00:06:57,419 to do 113 00:06:57,419 --> 00:07:02,020 We are really very excited! A new union has been formed 114 00:07:02,020 --> 00:07:04,630 within the periodic table and it has been done here at 115 00:07:04,630 --> 00:07:04,940 Nottingham.