[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.09,0:00:01.56,Default,,0000,0000,0000,,- [Instructor] If you zoom into water,
Dialogue: 0,0:00:01.56,0:00:03.66,Default,,0000,0000,0000,,you'll find a molecule of water
Dialogue: 0,0:00:03.66,0:00:05.58,Default,,0000,0000,0000,,where you have one oxygen atom
Dialogue: 0,0:00:05.58,0:00:07.80,Default,,0000,0000,0000,,attached to two hydrogen atoms.
Dialogue: 0,0:00:07.80,0:00:10.44,Default,,0000,0000,0000,,You'll find trillions\Nand trillions of them.
Dialogue: 0,0:00:10.44,0:00:12.87,Default,,0000,0000,0000,,Similarly, if you're to zoom into methane,
Dialogue: 0,0:00:12.87,0:00:15.00,Default,,0000,0000,0000,,which we also call natural gas,
Dialogue: 0,0:00:15.00,0:00:17.82,Default,,0000,0000,0000,,you will now find molecules of methane,
Dialogue: 0,0:00:17.82,0:00:20.61,Default,,0000,0000,0000,,which happens to be one carbon atom
Dialogue: 0,0:00:20.61,0:00:22.26,Default,,0000,0000,0000,,attached to four hydrogen atoms.
Dialogue: 0,0:00:22.26,0:00:25.77,Default,,0000,0000,0000,,Again, you'll find trillions\Nand trillions of them.
Dialogue: 0,0:00:25.77,0:00:28.08,Default,,0000,0000,0000,,So the big question now\Nis what would you get
Dialogue: 0,0:00:28.08,0:00:32.13,Default,,0000,0000,0000,,if you were to zoom into\Ntable salt, which is NaCl?
Dialogue: 0,0:00:32.13,0:00:36.15,Default,,0000,0000,0000,,Well, our guess could be,\Nwe'll find molecules of NaCl,
Dialogue: 0,0:00:36.15,0:00:39.18,Default,,0000,0000,0000,,where one Na is attached to one Cl.
Dialogue: 0,0:00:39.18,0:00:41.64,Default,,0000,0000,0000,,Trillions and trillions of them, right?
Dialogue: 0,0:00:41.64,0:00:43.50,Default,,0000,0000,0000,,Wrong. That's not what we'd get.
Dialogue: 0,0:00:43.50,0:00:46.08,Default,,0000,0000,0000,,We'll get something completely different.
Dialogue: 0,0:00:46.08,0:00:48.84,Default,,0000,0000,0000,,But what? Well, let's find out.
Dialogue: 0,0:00:48.84,0:00:51.45,Default,,0000,0000,0000,,So what will we find if\Nwe were to zoom into NaCl?
Dialogue: 0,0:00:51.45,0:00:54.15,Default,,0000,0000,0000,,We'll get something like this
Dialogue: 0,0:00:54.15,0:00:57.39,Default,,0000,0000,0000,,where you'll find trillions\Nof Na's and trillions of Cl
Dialogue: 0,0:00:57.39,0:00:59.67,Default,,0000,0000,0000,,all connected to each other.
Dialogue: 0,0:00:59.67,0:01:02.88,Default,,0000,0000,0000,,We call this a crystal of sodium chloride,
Dialogue: 0,0:01:02.88,0:01:03.99,Default,,0000,0000,0000,,a crystal of NaCl.
Dialogue: 0,0:01:03.99,0:01:05.28,Default,,0000,0000,0000,,You probably heard of this word crystal.
Dialogue: 0,0:01:05.28,0:01:09.60,Default,,0000,0000,0000,,It means we have an\Norderly repeating pattern.
Dialogue: 0,0:01:09.60,0:01:10.83,Default,,0000,0000,0000,,This looks very different, right?
Dialogue: 0,0:01:10.83,0:01:13.32,Default,,0000,0000,0000,,So let's compare it with\Nwhat we saw earlier.
Dialogue: 0,0:01:13.32,0:01:15.51,Default,,0000,0000,0000,,If we were to go back to\Nthe molecules of water,
Dialogue: 0,0:01:15.51,0:01:17.94,Default,,0000,0000,0000,,what we find is that an\Nindividual oxygen atom
Dialogue: 0,0:01:17.94,0:01:21.00,Default,,0000,0000,0000,,is connected to two other hydrogen atoms,
Dialogue: 0,0:01:21.00,0:01:22.80,Default,,0000,0000,0000,,and, you know, that connection
Dialogue: 0,0:01:22.80,0:01:24.15,Default,,0000,0000,0000,,is due to a force of attraction,
Dialogue: 0,0:01:24.15,0:01:25.77,Default,,0000,0000,0000,,which we call a chemical bond.
Dialogue: 0,0:01:25.77,0:01:26.94,Default,,0000,0000,0000,,The same thing is happening over here.
Dialogue: 0,0:01:26.94,0:01:29.31,Default,,0000,0000,0000,,There's a chemical bond\Nbecause of which a carbon atom
Dialogue: 0,0:01:29.31,0:01:31.65,Default,,0000,0000,0000,,is attached to four hydrogen atoms, right?
Dialogue: 0,0:01:31.65,0:01:34.26,Default,,0000,0000,0000,,But when it comes to a crystal of NaCl,
Dialogue: 0,0:01:34.26,0:01:37.08,Default,,0000,0000,0000,,look, we don't have individual molecules
Dialogue: 0,0:01:37.08,0:01:38.31,Default,,0000,0000,0000,,like what we see over here.
Dialogue: 0,0:01:38.31,0:01:39.36,Default,,0000,0000,0000,,We don't find them.
Dialogue: 0,0:01:39.36,0:01:42.48,Default,,0000,0000,0000,,Instead, we find trillions\Nand trillions of Na's
Dialogue: 0,0:01:42.48,0:01:44.58,Default,,0000,0000,0000,,connected to trillions and trillions of Cl
Dialogue: 0,0:01:44.58,0:01:45.93,Default,,0000,0000,0000,,in that chemical bond.
Dialogue: 0,0:01:45.93,0:01:49.14,Default,,0000,0000,0000,,So there are no individual molecules.
Dialogue: 0,0:01:49.14,0:01:50.61,Default,,0000,0000,0000,,You only have a crystal.
Dialogue: 0,0:01:50.61,0:01:52.62,Default,,0000,0000,0000,,But wait a second, wait\Na second, wait a second.
Dialogue: 0,0:01:52.62,0:01:55.05,Default,,0000,0000,0000,,Again, if you go back\Nto molecule of water,
Dialogue: 0,0:01:55.05,0:01:57.84,Default,,0000,0000,0000,,the reason why we call it H2O
Dialogue: 0,0:01:57.84,0:01:59.94,Default,,0000,0000,0000,,is because you have two hydrogen atoms
Dialogue: 0,0:01:59.94,0:02:02.01,Default,,0000,0000,0000,,connected to one oxygen atom
Dialogue: 0,0:02:02.01,0:02:04.77,Default,,0000,0000,0000,,to form a single unit molecule, right?
Dialogue: 0,0:02:04.77,0:02:06.06,Default,,0000,0000,0000,,Same is the case over here.
Dialogue: 0,0:02:06.06,0:02:09.63,Default,,0000,0000,0000,,It's because you have one\Ncarbonate has to four hydrogens,
Dialogue: 0,0:02:09.63,0:02:14.04,Default,,0000,0000,0000,,that's why we say the,\Nyou know, this is CH4.
Dialogue: 0,0:02:14.04,0:02:17.25,Default,,0000,0000,0000,,But what about over here?\NWhy do we call it NaCl?
Dialogue: 0,0:02:17.25,0:02:18.69,Default,,0000,0000,0000,,I mean, if you don't have\Nindividual molecules,
Dialogue: 0,0:02:18.69,0:02:21.42,Default,,0000,0000,0000,,what does it mean to say NaCl?
Dialogue: 0,0:02:21.42,0:02:23.22,Default,,0000,0000,0000,,Well, what it means is that
Dialogue: 0,0:02:23.22,0:02:25.50,Default,,0000,0000,0000,,if you're to take a chunk of this crystal,
Dialogue: 0,0:02:25.50,0:02:28.74,Default,,0000,0000,0000,,then you'll find equal\Namounts of Na and Cl.
Dialogue: 0,0:02:28.74,0:02:31.62,Default,,0000,0000,0000,,In other words, you'll have\Nthem in the ratio one is to one.
Dialogue: 0,0:02:31.62,0:02:34.89,Default,,0000,0000,0000,,For every one Na, you'll find one Cl.
Dialogue: 0,0:02:34.89,0:02:37.62,Default,,0000,0000,0000,,That is what that means over here.
Dialogue: 0,0:02:37.62,0:02:40.23,Default,,0000,0000,0000,,It doesn't mean that you'll\Nfind a molecule of NaCl
Dialogue: 0,0:02:40.23,0:02:42.15,Default,,0000,0000,0000,,where one Na is attached to one Cl.
Dialogue: 0,0:02:42.15,0:02:43.89,Default,,0000,0000,0000,,No, no, no. You find a crystal.
Dialogue: 0,0:02:43.89,0:02:46.86,Default,,0000,0000,0000,,But the ratio of Na and\NCl is one is to one.
Dialogue: 0,0:02:46.86,0:02:48.45,Default,,0000,0000,0000,,That's what it means over here.
Dialogue: 0,0:02:48.45,0:02:51.45,Default,,0000,0000,0000,,And we can take another\Nexample of the a salt.
Dialogue: 0,0:02:51.45,0:02:52.98,Default,,0000,0000,0000,,There are other salts as well.
Dialogue: 0,0:02:52.98,0:02:55.26,Default,,0000,0000,0000,,So for example, if you\Ntake potassium oxide,
Dialogue: 0,0:02:55.26,0:02:58.77,Default,,0000,0000,0000,,which also happens to be a salt, it is K2O
Dialogue: 0,0:02:58.77,0:03:00.87,Default,,0000,0000,0000,,where K is potassium\Nand O is oxygen, okay?
Dialogue: 0,0:03:00.87,0:03:02.58,Default,,0000,0000,0000,,But what does it mean to say K2O?
Dialogue: 0,0:03:02.58,0:03:04.44,Default,,0000,0000,0000,,Does it mean that there\Nare molecules of K2O?
Dialogue: 0,0:03:04.44,0:03:07.35,Default,,0000,0000,0000,,No, this is, again, a crystal.
Dialogue: 0,0:03:07.35,0:03:09.84,Default,,0000,0000,0000,,It's a crystal of potassium oxide.
Dialogue: 0,0:03:09.84,0:03:11.82,Default,,0000,0000,0000,,But what does it mean for us to say K2O?
Dialogue: 0,0:03:11.82,0:03:14.64,Default,,0000,0000,0000,,Well, what it means now is that\Nif you were to take a chunk
Dialogue: 0,0:03:14.64,0:03:16.02,Default,,0000,0000,0000,,of this crystal,
Dialogue: 0,0:03:16.02,0:03:19.62,Default,,0000,0000,0000,,you will find that there\Nare twice as many potassium
Dialogue: 0,0:03:19.62,0:03:20.91,Default,,0000,0000,0000,,as oxygen.
Dialogue: 0,0:03:20.91,0:03:24.78,Default,,0000,0000,0000,,You'll have two potassium\Natoms for every oxygen atom.
Dialogue: 0,0:03:24.78,0:03:27.51,Default,,0000,0000,0000,,That's what it means to say it is K2O.
Dialogue: 0,0:03:30.12,0:03:31.44,Default,,0000,0000,0000,,So putting it all together,
Dialogue: 0,0:03:31.44,0:03:33.78,Default,,0000,0000,0000,,what we have so far is that we can have
Dialogue: 0,0:03:33.78,0:03:34.71,Default,,0000,0000,0000,,two kinds of compounds.
Dialogue: 0,0:03:34.71,0:03:37.38,Default,,0000,0000,0000,,We have compounds that are\Nmade of individual molecules,
Dialogue: 0,0:03:37.38,0:03:41.07,Default,,0000,0000,0000,,and we have compounds\Nwhich are made of crystals.
Dialogue: 0,0:03:41.07,0:03:41.90,Default,,0000,0000,0000,,Now, of course,
Dialogue: 0,0:03:41.90,0:03:43.71,Default,,0000,0000,0000,,these are just two general\Ncategories of compounds,
Dialogue: 0,0:03:43.71,0:03:46.32,Default,,0000,0000,0000,,but there are more advanced\Nforms of compounds as well.
Dialogue: 0,0:03:46.32,0:03:48.06,Default,,0000,0000,0000,,We'll not worry too much about them.
Dialogue: 0,0:03:48.06,0:03:50.31,Default,,0000,0000,0000,,But anyways, the compounds\Nthat are made of molecules
Dialogue: 0,0:03:50.31,0:03:52.05,Default,,0000,0000,0000,,are called molecular compounds,
Dialogue: 0,0:03:52.05,0:03:53.19,Default,,0000,0000,0000,,and the ones that are made of crystals
Dialogue: 0,0:03:53.19,0:03:55.17,Default,,0000,0000,0000,,are called crystalline compounds.
Dialogue: 0,0:03:55.17,0:03:59.49,Default,,0000,0000,0000,,So look, not all compounds\Nare made of molecules.
Dialogue: 0,0:03:59.49,0:04:00.45,Default,,0000,0000,0000,,That's the important thing.
Dialogue: 0,0:04:00.45,0:04:01.74,Default,,0000,0000,0000,,They can also be crystalline.
Dialogue: 0,0:04:01.74,0:04:03.66,Default,,0000,0000,0000,,They can also be made of crystals.
Dialogue: 0,0:04:03.66,0:04:05.13,Default,,0000,0000,0000,,But here's an interesting question.
Dialogue: 0,0:04:05.13,0:04:07.29,Default,,0000,0000,0000,,Not all compounds are molecules, right?
Dialogue: 0,0:04:07.29,0:04:08.70,Default,,0000,0000,0000,,But what about the other way around?
Dialogue: 0,0:04:08.70,0:04:11.22,Default,,0000,0000,0000,,Are all molecules\Ncompounds? Well, let's see.
Dialogue: 0,0:04:11.22,0:04:14.79,Default,,0000,0000,0000,,Let's take an example. What if\Nwe were to zoom into oxygen?
Dialogue: 0,0:04:14.79,0:04:16.77,Default,,0000,0000,0000,,Well, we'll find that two atoms of oxygen
Dialogue: 0,0:04:16.77,0:04:18.96,Default,,0000,0000,0000,,are combined together to form O2,
Dialogue: 0,0:04:18.96,0:04:21.51,Default,,0000,0000,0000,,which is a molecule of oxygen.
Dialogue: 0,0:04:21.51,0:04:23.82,Default,,0000,0000,0000,,And of course, you'll find\Ntrillions and trillions of them.
Dialogue: 0,0:04:23.82,0:04:26.49,Default,,0000,0000,0000,,But the big question is\N"Is this a compound?"
Dialogue: 0,0:04:26.49,0:04:29.01,Default,,0000,0000,0000,,The answer is no. It's not a compound.
Dialogue: 0,0:04:29.01,0:04:31.38,Default,,0000,0000,0000,,Because remember, compounds\Nare chemical combination
Dialogue: 0,0:04:31.38,0:04:33.96,Default,,0000,0000,0000,,of two or more different elements.
Dialogue: 0,0:04:33.96,0:04:36.84,Default,,0000,0000,0000,,Here, there's a chemical\Ncombination of the same element.
Dialogue: 0,0:04:36.84,0:04:38.67,Default,,0000,0000,0000,,Oxygen and oxygen is getting combined.
Dialogue: 0,0:04:38.67,0:04:42.57,Default,,0000,0000,0000,,So it's a molecule, but\Nit is not a compound.
Dialogue: 0,0:04:42.57,0:04:46.26,Default,,0000,0000,0000,,In fact, we call this as diatomic element.
Dialogue: 0,0:04:46.26,0:04:48.00,Default,,0000,0000,0000,,Because di- because there are two,
Dialogue: 0,0:04:48.00,0:04:50.10,Default,,0000,0000,0000,,and there are other examples\Nof diatomic elements.
Dialogue: 0,0:04:50.10,0:04:54.39,Default,,0000,0000,0000,,Nitrogen, fluorine,\Nchlorine, and many more.
Dialogue: 0,0:04:54.39,0:04:56.13,Default,,0000,0000,0000,,But of course, one thing to\Nremember is that these elements
Dialogue: 0,0:04:56.13,0:04:58.71,Default,,0000,0000,0000,,are usually diatomic when they're alone,
Dialogue: 0,0:04:58.71,0:05:01.41,Default,,0000,0000,0000,,like when you have oxygen\Ngas or chlorine gas.
Dialogue: 0,0:05:01.41,0:05:03.48,Default,,0000,0000,0000,,But of course, when\Nthey do form a compound,
Dialogue: 0,0:05:03.48,0:05:04.98,Default,,0000,0000,0000,,they can split apart.
Dialogue: 0,0:05:04.98,0:05:07.11,Default,,0000,0000,0000,,Again, go back to molecule of water.
Dialogue: 0,0:05:07.11,0:05:11.94,Default,,0000,0000,0000,,You can have one oxygen atom\Ncombined to two hydrogen atoms.
Dialogue: 0,0:05:11.94,0:05:13.86,Default,,0000,0000,0000,,Anyways, if you were\Nto put it all together,
Dialogue: 0,0:05:13.86,0:05:16.38,Default,,0000,0000,0000,,we have elements which are the\Nfundamental building blocks
Dialogue: 0,0:05:16.38,0:05:17.21,Default,,0000,0000,0000,,of matter.
Dialogue: 0,0:05:17.21,0:05:19.41,Default,,0000,0000,0000,,Some elements are made\Nof individual atoms.
Dialogue: 0,0:05:19.41,0:05:20.88,Default,,0000,0000,0000,,We usually call them monoatomic.
Dialogue: 0,0:05:20.88,0:05:24.15,Default,,0000,0000,0000,,Mono- for single, individual,\Nlike gold or mercury.
Dialogue: 0,0:05:24.15,0:05:26.88,Default,,0000,0000,0000,,And other elements can\Nbe formed as diatomic,
Dialogue: 0,0:05:26.88,0:05:29.28,Default,,0000,0000,0000,,like molecules of nitrogen or oxygen.
Dialogue: 0,0:05:29.28,0:05:30.99,Default,,0000,0000,0000,,And then two or more different elements
Dialogue: 0,0:05:30.99,0:05:32.46,Default,,0000,0000,0000,,chemically combined together,
Dialogue: 0,0:05:32.46,0:05:33.63,Default,,0000,0000,0000,,we get compounds.
Dialogue: 0,0:05:33.63,0:05:35.16,Default,,0000,0000,0000,,We can have molecular compounds
Dialogue: 0,0:05:35.16,0:05:37.47,Default,,0000,0000,0000,,where you find individual molecules,
Dialogue: 0,0:05:37.47,0:05:39.33,Default,,0000,0000,0000,,or we can have crystalline compounds
Dialogue: 0,0:05:39.33,0:05:42.06,Default,,0000,0000,0000,,when there are no molecules at all.
Dialogue: 0,0:05:42.06,0:05:45.30,Default,,0000,0000,0000,,And finally, we categorize this all under
Dialogue: 0,0:05:45.30,0:05:48.24,Default,,0000,0000,0000,,what we call pure substances
Dialogue: 0,0:05:48.24,0:05:50.16,Default,,0000,0000,0000,,because they're made of\Npurely the same stuff.
Dialogue: 0,0:05:50.16,0:05:53.25,Default,,0000,0000,0000,,For example, water is purely\Nmade of water molecules.
Dialogue: 0,0:05:53.25,0:05:56.31,Default,,0000,0000,0000,,Sodium chloride is purely made of NaCl.
Dialogue: 0,0:05:56.31,0:05:57.93,Default,,0000,0000,0000,,And well, oxygen, for example,
Dialogue: 0,0:05:57.93,0:05:59.67,Default,,0000,0000,0000,,is purely made of oxygen molecules.
Dialogue: 0,0:05:59.67,0:06:02.13,Default,,0000,0000,0000,,So because they're all made\Nof purely the same stuff,
Dialogue: 0,0:06:02.13,0:06:04.53,Default,,0000,0000,0000,,these are all pure substances.