[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:01.84,0:00:03.44,Default,,0000,0000,0000,,Hank: Hello, I'm Hank.
Dialogue: 0,0:00:03.44,0:00:04.74,Default,,0000,0000,0000,,I assume that you are here
Dialogue: 0,0:00:04.74,0:00:06.62,Default,,0000,0000,0000,,because you are interested in biology.
Dialogue: 0,0:00:06.62,0:00:08.37,Default,,0000,0000,0000,,If you are, that makes sense,
Dialogue: 0,0:00:08.37,0:00:10.49,Default,,0000,0000,0000,,because like any good 50 Cent song,
Dialogue: 0,0:00:10.49,0:00:13.91,Default,,0000,0000,0000,,Biology is just about sex and not dying,
Dialogue: 0,0:00:13.91,0:00:15.97,Default,,0000,0000,0000,,and everyone watching this\Nshould be interested in sex
Dialogue: 0,0:00:15.97,0:00:19.35,Default,,0000,0000,0000,,and not dying, being that you\Nare, I assume, a human being.
Dialogue: 0,0:00:19.35,0:00:21.19,Default,,0000,0000,0000,,I'm gonna teach this biology\Ncourse a little differently
Dialogue: 0,0:00:21.19,0:00:23.02,Default,,0000,0000,0000,,than most courses you've ever experienced.
Dialogue: 0,0:00:23.02,0:00:25.44,Default,,0000,0000,0000,,For example, I'm not going\Nto spend the first class
Dialogue: 0,0:00:25.44,0:00:27.89,Default,,0000,0000,0000,,talking about how I'm\Ngoing to teach the class.
Dialogue: 0,0:00:27.89,0:00:29.73,Default,,0000,0000,0000,,I'm just going to start\Nteaching the class.
Dialogue: 0,0:00:29.73,0:00:32.10,Default,,0000,0000,0000,,Starting right after this next cut.
Dialogue: 0,0:00:32.10,0:00:34.31,Default,,0000,0000,0000,,First, I just wanted to say\Nif I'm going to fast for you,
Dialogue: 0,0:00:34.31,0:00:37.37,Default,,0000,0000,0000,,the great thing about me\Nbeing a video and not a person
Dialogue: 0,0:00:37.37,0:00:40.57,Default,,0000,0000,0000,,is that you can always go back and\Nlisten to what I've said again.
Dialogue: 0,0:00:40.57,0:00:42.45,Default,,0000,0000,0000,,I promise I will not mind.
Dialogue: 0,0:00:42.45,0:00:44.57,Default,,0000,0000,0000,,You are encouraged to do this often.
Dialogue: 0,0:00:44.57,0:00:46.19,Default,,0000,0000,0000,,A great professor of mine once told me
Dialogue: 0,0:00:46.19,0:00:48.12,Default,,0000,0000,0000,,that in order to understand any topic,
Dialogue: 0,0:00:48.12,0:00:50.12,Default,,0000,0000,0000,,you only really need to\Nunderstand a bit of the level
Dialogue: 0,0:00:50.12,0:00:52.38,Default,,0000,0000,0000,,of complexity just below that topic.
Dialogue: 0,0:00:52.39,0:00:55.52,Default,,0000,0000,0000,,The level of complexity just\Nbelow biology is chemistry,
Dialogue: 0,0:00:55.52,0:00:56.87,Default,,0000,0000,0000,,or if you're a biochemist,
Dialogue: 0,0:00:56.87,0:00:59.04,Default,,0000,0000,0000,,you would probably argue\Nthat it's biochemistry,
Dialogue: 0,0:00:59.03,0:01:02.19,Default,,0000,0000,0000,,so we need to know a little\Nbit more about chemistry,
Dialogue: 0,0:01:02.19,0:01:04.47,Default,,0000,0000,0000,,and that is where we're gonna start.
Dialogue: 0,0:01:04.47,0:01:06.75,Default,,0000,0000,0000,,(lively intro music)
Dialogue: 0,0:01:14.06,0:01:17.34,Default,,0000,0000,0000,,I'm a collection of organic\Ncompounds called Hank Green.
Dialogue: 0,0:01:17.34,0:01:20.26,Default,,0000,0000,0000,,An organic compound is\Nmore or less any chemical
Dialogue: 0,0:01:20.26,0:01:21.52,Default,,0000,0000,0000,,that contains carbon,
Dialogue: 0,0:01:21.52,0:01:23.77,Default,,0000,0000,0000,,and carbon is awesome.
Dialogue: 0,0:01:23.77,0:01:25.48,Default,,0000,0000,0000,,Why? Lots of reasons.
Dialogue: 0,0:01:25.48,0:01:26.94,Default,,0000,0000,0000,,I'm gonna give you three.
Dialogue: 0,0:01:26.94,0:01:28.64,Default,,0000,0000,0000,,First, carbon is small.
Dialogue: 0,0:01:28.64,0:01:30.69,Default,,0000,0000,0000,,It doesn't have that many\Nprotons and neutrons.
Dialogue: 0,0:01:30.69,0:01:34.12,Default,,0000,0000,0000,,Almost always 12, rarely\Nit has some extra neutrons
Dialogue: 0,0:01:34.12,0:01:36.09,Default,,0000,0000,0000,,making it C-13 or C-14.
Dialogue: 0,0:01:36.09,0:01:39.45,Default,,0000,0000,0000,,Because of that, carbon does\Nnot take up a lot of space
Dialogue: 0,0:01:39.45,0:01:41.82,Default,,0000,0000,0000,,and can form itself into elegant shapes.
Dialogue: 0,0:01:41.82,0:01:43.02,Default,,0000,0000,0000,,It can form rings.
Dialogue: 0,0:01:43.02,0:01:45.08,Default,,0000,0000,0000,,It can form double or even triple bonds.
Dialogue: 0,0:01:45.08,0:01:46.99,Default,,0000,0000,0000,,It can form spirals and sheets
Dialogue: 0,0:01:46.99,0:01:48.67,Default,,0000,0000,0000,,and all kinds of really awesome things
Dialogue: 0,0:01:48.67,0:01:50.47,Default,,0000,0000,0000,,that bigger molecules\Nwould never manage to do.
Dialogue: 0,0:01:50.47,0:01:52.77,Default,,0000,0000,0000,,Basically, carbon is\Nlike an olympic gymnast.
Dialogue: 0,0:01:52.77,0:01:55.81,Default,,0000,0000,0000,,It can only do the remarkable\Nand beautiful things it can do
Dialogue: 0,0:01:55.81,0:01:56.87,Default,,0000,0000,0000,,because it's petite.
Dialogue: 0,0:01:56.87,0:01:58.72,Default,,0000,0000,0000,,Second, carbon is kind.
Dialogue: 0,0:01:58.72,0:01:59.93,Default,,0000,0000,0000,,It's not like other elements that
Dialogue: 0,0:01:59.93,0:02:02.73,Default,,0000,0000,0000,,desperately want to gain\Nor lose or share electrons
Dialogue: 0,0:02:02.73,0:02:04.39,Default,,0000,0000,0000,,to get the exact number they want.
Dialogue: 0,0:02:04.39,0:02:06.71,Default,,0000,0000,0000,,No, carbon knows what\Nit's like to be lonely,
Dialogue: 0,0:02:06.71,0:02:10.17,Default,,0000,0000,0000,,so it's not all, "I can't\Nlive without your electrons."
Dialogue: 0,0:02:10.17,0:02:12.32,Default,,0000,0000,0000,,Needy, like chlorine or sodium is.
Dialogue: 0,0:02:12.32,0:02:14.91,Default,,0000,0000,0000,,This is why chlorine\Ntears apart your insides
Dialogue: 0,0:02:14.91,0:02:16.25,Default,,0000,0000,0000,,if you breathe it in gaseous form,
Dialogue: 0,0:02:16.25,0:02:19.69,Default,,0000,0000,0000,,and why sodium metal, if\Ningested, will explode.
Dialogue: 0,0:02:19.69,0:02:21.34,Default,,0000,0000,0000,,Carbon, though, eh.
Dialogue: 0,0:02:21.34,0:02:24.42,Default,,0000,0000,0000,,It wants more electrons, but\Nit's not going to kill for them.
Dialogue: 0,0:02:24.42,0:02:25.32,Default,,0000,0000,0000,,It's easy to work with.
Dialogue: 0,0:02:25.32,0:02:27.99,Default,,0000,0000,0000,,It makes and breaks bonds\Nlike a 13-year-old mall rat,
Dialogue: 0,0:02:27.99,0:02:29.75,Default,,0000,0000,0000,,but it doesn't ever really hold a grudge.
Dialogue: 0,0:02:29.75,0:02:32.97,Default,,0000,0000,0000,,Third, carbon loves to bond
Dialogue: 0,0:02:32.97,0:02:34.92,Default,,0000,0000,0000,,because it needs 4 extra electrons,
Dialogue: 0,0:02:34.92,0:02:37.84,Default,,0000,0000,0000,,so it will bond with whoever\Nhappens to be nearby.
Dialogue: 0,0:02:37.84,0:02:40.77,Default,,0000,0000,0000,,Usually, it will bond\Nwith 2 or 3 or 4 of them
Dialogue: 0,0:02:40.77,0:02:41.67,Default,,0000,0000,0000,,at the same time.
Dialogue: 0,0:02:41.67,0:02:42.97,Default,,0000,0000,0000,,Carbon can bond with lots\Nof different elements.
Dialogue: 0,0:02:42.97,0:02:45.24,Default,,0000,0000,0000,,Hydrogen, oxygen, phosphorus, nitrogen,
Dialogue: 0,0:02:45.24,0:02:46.75,Default,,0000,0000,0000,,and other atoms of carbon.
Dialogue: 0,0:02:46.75,0:02:48.98,Default,,0000,0000,0000,,It can do this in infinite configurations,
Dialogue: 0,0:02:48.98,0:02:52.33,Default,,0000,0000,0000,,allowing it to be the core element\Nof the complicated structures
Dialogue: 0,0:02:52.33,0:02:54.66,Default,,0000,0000,0000,,that make living things like ourselves.
Dialogue: 0,0:02:54.66,0:02:57.42,Default,,0000,0000,0000,,Because carbon is small,\Nkind, and loves to bond,
Dialogue: 0,0:02:57.42,0:02:59.17,Default,,0000,0000,0000,,life is pretty much built around it.
Dialogue: 0,0:02:59.17,0:03:01.42,Default,,0000,0000,0000,,Carbon is the foundation of biology.
Dialogue: 0,0:03:01.42,0:03:03.46,Default,,0000,0000,0000,,So fundamental that\Nscientists have a hard time
Dialogue: 0,0:03:03.46,0:03:06.92,Default,,0000,0000,0000,,even conceiving of life\Nthat is not carbon-based.
Dialogue: 0,0:03:06.92,0:03:09.42,Default,,0000,0000,0000,,Silicon, which is analogous\Nto carbon in many ways,
Dialogue: 0,0:03:09.42,0:03:11.29,Default,,0000,0000,0000,,is often cited as a potential element
Dialogue: 0,0:03:11.29,0:03:12.79,Default,,0000,0000,0000,,for alien life to be based on,
Dialogue: 0,0:03:12.79,0:03:14.92,Default,,0000,0000,0000,,but it's bulkier, so it doesn't form
Dialogue: 0,0:03:14.92,0:03:16.58,Default,,0000,0000,0000,,the same elegant shapes as carbon.
Dialogue: 0,0:03:16.58,0:03:18.50,Default,,0000,0000,0000,,It's also not found in any gases,
Dialogue: 0,0:03:18.50,0:03:20.07,Default,,0000,0000,0000,,meaning that life would have to be formed
Dialogue: 0,0:03:20.07,0:03:22.17,Default,,0000,0000,0000,,by eating solid silicon,
Dialogue: 0,0:03:22.17,0:03:24.35,Default,,0000,0000,0000,,whereas life here on\Nearth is only possible
Dialogue: 0,0:03:24.35,0:03:26.92,Default,,0000,0000,0000,,because carbon is constantly\Nfloating around in the air
Dialogue: 0,0:03:26.92,0:03:28.28,Default,,0000,0000,0000,,in the form of carbon dioxide.
Dialogue: 0,0:03:28.28,0:03:31.16,Default,,0000,0000,0000,,Carbon, on its own, is\Nan atom with 6 protons,
Dialogue: 0,0:03:31.16,0:03:33.37,Default,,0000,0000,0000,,6 electrons, and 6 neutrons.
Dialogue: 0,0:03:33.37,0:03:35.17,Default,,0000,0000,0000,,Atoms have electron shells,
Dialogue: 0,0:03:35.17,0:03:38.08,Default,,0000,0000,0000,,and they need or want to\Nhave these shells filled,
Dialogue: 0,0:03:38.08,0:03:40.29,Default,,0000,0000,0000,,in order to be happy, fulfilled atoms.
Dialogue: 0,0:03:40.29,0:03:42.20,Default,,0000,0000,0000,,The first electron shell\Ncalled the S-orbital
Dialogue: 0,0:03:42.20,0:03:44.04,Default,,0000,0000,0000,,needs 2 electrons to be full.
Dialogue: 0,0:03:44.04,0:03:47.17,Default,,0000,0000,0000,,Then there's the 2nd\NS-orbital, which also needs 2,
Dialogue: 0,0:03:47.17,0:03:48.62,Default,,0000,0000,0000,,carbon has this filled as well.
Dialogue: 0,0:03:48.62,0:03:51.04,Default,,0000,0000,0000,,Then we have the first P-orbital,
Dialogue: 0,0:03:51.04,0:03:52.66,Default,,0000,0000,0000,,which needs 6 to be full.
Dialogue: 0,0:03:52.66,0:03:56.42,Default,,0000,0000,0000,,Carbon only has 2 left\Nover, so it wants 4 more.
Dialogue: 0,0:03:56.42,0:03:58.70,Default,,0000,0000,0000,,Carbon forms a lot of bonds\Nthat we call "covalent".
Dialogue: 0,0:03:58.70,0:04:01.44,Default,,0000,0000,0000,,These are bonds where the\Natoms actually share electrons,
Dialogue: 0,0:04:01.44,0:04:04.48,Default,,0000,0000,0000,,so the simplest carbon\Ncompound ever, methane,
Dialogue: 0,0:04:04.48,0:04:06.52,Default,,0000,0000,0000,,is carbon sharing 4 electrons
Dialogue: 0,0:04:06.52,0:04:08.02,Default,,0000,0000,0000,,with 4 hydrogen atoms.
Dialogue: 0,0:04:08.02,0:04:10.06,Default,,0000,0000,0000,,Hydrogen only has 1 electron,
Dialogue: 0,0:04:10.06,0:04:12.43,Default,,0000,0000,0000,,so it wants its first S-orbital full.
Dialogue: 0,0:04:12.43,0:04:15.08,Default,,0000,0000,0000,,Carbon shares its 4 electrons\Nwith those 4 hydrogens,
Dialogue: 0,0:04:15.08,0:04:18.02,Default,,0000,0000,0000,,and those 4 hydrogens each\Nshare 1 electron with carbon,
Dialogue: 0,0:04:18.02,0:04:18.84,Default,,0000,0000,0000,,so everybody's happy.
Dialogue: 0,0:04:18.84,0:04:21.04,Default,,0000,0000,0000,,This can all be represented\Nwith what we call
Dialogue: 0,0:04:21.04,0:04:22.71,Default,,0000,0000,0000,,Lewis dot structures.
Dialogue: 0,0:04:22.71,0:04:25.88,Default,,0000,0000,0000,,Gilbert Lewis, also the guy\Nbehind Lewis acids and bases,
Dialogue: 0,0:04:25.88,0:04:28.93,Default,,0000,0000,0000,,was nominated for the Nobel Prize 35 times
Dialogue: 0,0:04:28.93,0:04:30.58,Default,,0000,0000,0000,,and won none.
Dialogue: 0,0:04:30.58,0:04:33.52,Default,,0000,0000,0000,,This is more nominations\Nthan anyone else in history,
Dialogue: 0,0:04:33.52,0:04:36.89,Default,,0000,0000,0000,,and roughly the same number\Nof wins as everyone else.
Dialogue: 0,0:04:36.89,0:04:39.53,Default,,0000,0000,0000,,Lewis disliked this a great deal.
Dialogue: 0,0:04:39.53,0:04:41.86,Default,,0000,0000,0000,,He may have been the most\Ninfluential chemist of his time.
Dialogue: 0,0:04:41.86,0:04:43.42,Default,,0000,0000,0000,,He coined the term photon.
Dialogue: 0,0:04:43.42,0:04:45.77,Default,,0000,0000,0000,,He revolutionized how we\Nthink about acids and bases.
Dialogue: 0,0:04:45.77,0:04:48.33,Default,,0000,0000,0000,,He produced the first the\Nfirst molecule of heavy water,
Dialogue: 0,0:04:48.33,0:04:50.19,Default,,0000,0000,0000,,and he was the first\Nperson to conceptualize
Dialogue: 0,0:04:50.19,0:04:52.94,Default,,0000,0000,0000,,the covalent bond that we're\Ntalking about right now.
Dialogue: 0,0:04:52.94,0:04:55.51,Default,,0000,0000,0000,,But, he was extremely\Ndifficult to work with.
Dialogue: 0,0:04:55.51,0:04:58.34,Default,,0000,0000,0000,,He was forced to resign\Nfrom many important posts,
Dialogue: 0,0:04:58.34,0:05:00.80,Default,,0000,0000,0000,,and was also passed up\Nfor the Manhattan Project,
Dialogue: 0,0:05:00.80,0:05:03.70,Default,,0000,0000,0000,,so while all of his colleagues\Nworked to save his country,
Dialogue: 0,0:05:03.71,0:05:05.80,Default,,0000,0000,0000,,Lewis wrote a horrible novel.
Dialogue: 0,0:05:05.80,0:05:08.39,Default,,0000,0000,0000,,Lewis died alone in his laboratory
Dialogue: 0,0:05:08.39,0:05:11.41,Default,,0000,0000,0000,,while working on cyanide\Ncompounds after having had lunch
Dialogue: 0,0:05:11.41,0:05:13.90,Default,,0000,0000,0000,,with a younger, more charismatic colleague
Dialogue: 0,0:05:13.90,0:05:15.56,Default,,0000,0000,0000,,who had won the Nobel prize
Dialogue: 0,0:05:15.56,0:05:17.48,Default,,0000,0000,0000,,and worked on the Manhattan Project.
Dialogue: 0,0:05:17.48,0:05:20.05,Default,,0000,0000,0000,,Many suspect that he killed\Nhimself with the cyanide compounds
Dialogue: 0,0:05:20.05,0:05:21.08,Default,,0000,0000,0000,,that he was working on,
Dialogue: 0,0:05:21.08,0:05:23.23,Default,,0000,0000,0000,,but the medical examiner said heart attack
Dialogue: 0,0:05:23.23,0:05:24.65,Default,,0000,0000,0000,,without really looking into it.
Dialogue: 0,0:05:24.65,0:05:26.27,Default,,0000,0000,0000,,I told you all that because,
Dialogue: 0,0:05:26.27,0:05:29.40,Default,,0000,0000,0000,,well, the little Lewis structure\Nthat I'm about to show you
Dialogue: 0,0:05:29.39,0:05:32.69,Default,,0000,0000,0000,,was created by a deeply troubled genius.
Dialogue: 0,0:05:32.69,0:05:36.80,Default,,0000,0000,0000,,It's not some abstract scientific\Nthing that has always existed.
Dialogue: 0,0:05:36.80,0:05:38.43,Default,,0000,0000,0000,,Someone, somewhere, thought it up,
Dialogue: 0,0:05:38.43,0:05:41.16,Default,,0000,0000,0000,,and it was such a marvelously useful tool,
Dialogue: 0,0:05:41.16,0:05:42.81,Default,,0000,0000,0000,,that we've been using it ever since.
Dialogue: 0,0:05:42.81,0:05:45.14,Default,,0000,0000,0000,,In biology, most compounds can be shown
Dialogue: 0,0:05:45.14,0:05:46.69,Default,,0000,0000,0000,,in Lewis structure form.
Dialogue: 0,0:05:46.69,0:05:48.55,Default,,0000,0000,0000,,One of the rules of thumb\Nwhen making these diagrams
Dialogue: 0,0:05:48.55,0:05:50.70,Default,,0000,0000,0000,,is that some elements tend\Nto react with each other
Dialogue: 0,0:05:50.70,0:05:53.67,Default,,0000,0000,0000,,in such a way that each atom\Nends up with 8 electrons
Dialogue: 0,0:05:53.67,0:05:54.95,Default,,0000,0000,0000,,in its outermost shell.
Dialogue: 0,0:05:54.95,0:05:56.60,Default,,0000,0000,0000,,That's called the octet rule,
Dialogue: 0,0:05:56.60,0:05:58.40,Default,,0000,0000,0000,,because these atoms want to complete
Dialogue: 0,0:05:58.40,0:06:01.54,Default,,0000,0000,0000,,their octets of electrons\Nto be happy and satisfied.
Dialogue: 0,0:06:01.54,0:06:03.52,Default,,0000,0000,0000,,Oxygen has 6 electrons in its outer shell,
Dialogue: 0,0:06:03.52,0:06:06.49,Default,,0000,0000,0000,,and needs 2, which is why we get H2O.
Dialogue: 0,0:06:06.49,0:06:08.90,Default,,0000,0000,0000,,It can also bond with\Ncarbon, which needs 4,
Dialogue: 0,0:06:08.90,0:06:11.41,Default,,0000,0000,0000,,so 2 double bonds to 2\Ndifferent oxygen atoms,
Dialogue: 0,0:06:11.41,0:06:12.91,Default,,0000,0000,0000,,you end up with CO2,
Dialogue: 0,0:06:12.91,0:06:14.57,Default,,0000,0000,0000,,that pesky global warming gas,
Dialogue: 0,0:06:14.57,0:06:18.01,Default,,0000,0000,0000,,and also the stuff that plants\Nand, thus, all life are made of.
Dialogue: 0,0:06:18.01,0:06:20.68,Default,,0000,0000,0000,,Nitrogen has 5 electrons\Nin its outer shell.
Dialogue: 0,0:06:20.68,0:06:22.35,Default,,0000,0000,0000,,Here's how we count them.
Dialogue: 0,0:06:22.35,0:06:23.74,Default,,0000,0000,0000,,There are four placeholders.
Dialogue: 0,0:06:23.74,0:06:25.20,Default,,0000,0000,0000,,Each wants two atoms,
Dialogue: 0,0:06:25.20,0:06:26.80,Default,,0000,0000,0000,,and like people getting on a bus,
Dialogue: 0,0:06:26.80,0:06:29.62,Default,,0000,0000,0000,,they prefer to start out not\Nsitting next to each other.
Dialogue: 0,0:06:29.62,0:06:30.74,Default,,0000,0000,0000,,I'm not kidding about this.
Dialogue: 0,0:06:30.74,0:06:32.62,Default,,0000,0000,0000,,They really don't double\Nup until they have to.
Dialogue: 0,0:06:32.62,0:06:33.49,Default,,0000,0000,0000,,We count it out.
Dialogue: 0,0:06:33.49,0:06:35.83,Default,,0000,0000,0000,,1, 2, 3, 4, 5.
Dialogue: 0,0:06:35.83,0:06:37.49,Default,,0000,0000,0000,,So, for maximum happiness,
Dialogue: 0,0:06:37.49,0:06:39.80,Default,,0000,0000,0000,,nitrogen bonds with 3 hydrogens,
Dialogue: 0,0:06:39.80,0:06:40.96,Default,,0000,0000,0000,,forming ammonia,
Dialogue: 0,0:06:40.96,0:06:43.76,Default,,0000,0000,0000,,or with 2 hydrogens, sticking\Noff another group of atoms
Dialogue: 0,0:06:43.76,0:06:45.55,Default,,0000,0000,0000,,which we call an amino group.
Dialogue: 0,0:06:45.55,0:06:47.76,Default,,0000,0000,0000,,And if that amino group\Nis bonded to a carbon
Dialogue: 0,0:06:47.76,0:06:49.92,Default,,0000,0000,0000,,that is bonded to a carboxylic acid group,
Dialogue: 0,0:06:49.92,0:06:52.33,Default,,0000,0000,0000,,you have an amino acid.
Dialogue: 0,0:06:52.33,0:06:55.10,Default,,0000,0000,0000,,Sometimes electrons are shared\Nequally within a covalent bond
Dialogue: 0,0:06:55.10,0:06:56.18,Default,,0000,0000,0000,,like with O2.
Dialogue: 0,0:06:56.18,0:06:58.25,Default,,0000,0000,0000,,That's called a non-polar covalent bond,
Dialogue: 0,0:06:58.25,0:07:00.65,Default,,0000,0000,0000,,but often one of the\Nparticipants is more greedy.
Dialogue: 0,0:07:00.65,0:07:03.20,Default,,0000,0000,0000,,In water, for example, the oxygen molecule
Dialogue: 0,0:07:03.20,0:07:05.66,Default,,0000,0000,0000,,sucks the electorns in,\Nand they spend more time
Dialogue: 0,0:07:05.66,0:07:07.94,Default,,0000,0000,0000,,around the oxygen than\Naround the hydrogens.
Dialogue: 0,0:07:07.94,0:07:10.100,Default,,0000,0000,0000,,This creates a slight positive\Ncharge around the hydrogens
Dialogue: 0,0:07:10.100,0:07:13.24,Default,,0000,0000,0000,,and a slight negative\Ncharge around the oxygen.
Dialogue: 0,0:07:13.24,0:07:15.87,Default,,0000,0000,0000,,When something has a charge,\Nwe say that it's polar.
Dialogue: 0,0:07:15.87,0:07:18.04,Default,,0000,0000,0000,,It has a positive and negative pole.
Dialogue: 0,0:07:18.04,0:07:20.39,Default,,0000,0000,0000,,This is a polar covalent bond.
Dialogue: 0,0:07:20.39,0:07:22.83,Default,,0000,0000,0000,,Ionic bonds occur when\Ninstead of sharing electrons,
Dialogue: 0,0:07:22.83,0:07:25.08,Default,,0000,0000,0000,,atoms just donate or accept an electron
Dialogue: 0,0:07:25.08,0:07:26.70,Default,,0000,0000,0000,,from another atom completely
Dialogue: 0,0:07:26.70,0:07:30.35,Default,,0000,0000,0000,,and then live happily as\Na charged atom or ion.
Dialogue: 0,0:07:30.35,0:07:32.20,Default,,0000,0000,0000,,Atoms would, in general,\Nprefer to be neutral
Dialogue: 0,0:07:32.20,0:07:35.10,Default,,0000,0000,0000,,but compared with having\Nthe full electron shells
Dialogue: 0,0:07:35.10,0:07:36.36,Default,,0000,0000,0000,,is not that big of a deal.
Dialogue: 0,0:07:36.36,0:07:38.56,Default,,0000,0000,0000,,The most common ionic\Ncompound in our daily lives?
Dialogue: 0,0:07:38.56,0:07:42.98,Default,,0000,0000,0000,,that would be good old table\Nsalt, NaCl, sodium chloride,
Dialogue: 0,0:07:42.98,0:07:45.48,Default,,0000,0000,0000,,but don't be fooled by its deliciousness.
Dialogue: 0,0:07:45.48,0:07:47.80,Default,,0000,0000,0000,,Sodium chloride, as I\Npreviously mentioned,
Dialogue: 0,0:07:47.80,0:07:49.71,Default,,0000,0000,0000,,is made of 2 very nasty elements.
Dialogue: 0,0:07:49.71,0:07:51.56,Default,,0000,0000,0000,,Chlorine is a halogen,
Dialogue: 0,0:07:51.56,0:07:53.83,Default,,0000,0000,0000,,or an element that only needs one proton
Dialogue: 0,0:07:53.83,0:07:54.75,Default,,0000,0000,0000,,to fill its octet,
Dialogue: 0,0:07:54.75,0:07:56.81,Default,,0000,0000,0000,,while sodium is an alkali metal,
Dialogue: 0,0:07:56.81,0:07:59.33,Default,,0000,0000,0000,,an element that only has\None electron in its octet.
Dialogue: 0,0:07:59.33,0:08:01.84,Default,,0000,0000,0000,,They will happily tear\Napart any chemical compound
Dialogue: 0,0:08:01.84,0:08:03.18,Default,,0000,0000,0000,,they come in contact with,
Dialogue: 0,0:08:03.18,0:08:05.34,Default,,0000,0000,0000,,searching to satisfy the octet rule.
Dialogue: 0,0:08:05.34,0:08:08.93,Default,,0000,0000,0000,,No better outcome could occur\Nthan sodium meeting chlorine.
Dialogue: 0,0:08:08.93,0:08:10.65,Default,,0000,0000,0000,,They immediately transfer electrons
Dialogue: 0,0:08:10.65,0:08:12.45,Default,,0000,0000,0000,,so sodium doesn't have its extra
Dialogue: 0,0:08:12.45,0:08:14.23,Default,,0000,0000,0000,,and the chlorine fills its octet.
Dialogue: 0,0:08:14.23,0:08:16.45,Default,,0000,0000,0000,,They become Na+ and Cl-,
Dialogue: 0,0:08:16.45,0:08:18.56,Default,,0000,0000,0000,,and are so charged that\Nthey stick together,
Dialogue: 0,0:08:18.56,0:08:21.48,Default,,0000,0000,0000,,and that stickiness is\Nwhat we call an ionic bond.
Dialogue: 0,0:08:21.48,0:08:23.90,Default,,0000,0000,0000,,These chemical changes\Nare a big deal, remember?
Dialogue: 0,0:08:23.90,0:08:26.23,Default,,0000,0000,0000,,Sodium and chlorine just\Nwent from being deadly
Dialogue: 0,0:08:26.23,0:08:27.45,Default,,0000,0000,0000,,to being delicious.
Dialogue: 0,0:08:27.45,0:08:28.45,Default,,0000,0000,0000,,They're also hydrogen bonds,
Dialogue: 0,0:08:28.45,0:08:32.08,Default,,0000,0000,0000,,which aren't really bonds, so much.
Dialogue: 0,0:08:32.08,0:08:33.06,Default,,0000,0000,0000,,So, you remember water?
Dialogue: 0,0:08:33.06,0:08:34.64,Default,,0000,0000,0000,,I hope you didn't forget about water.
Dialogue: 0,0:08:34.64,0:08:35.67,Default,,0000,0000,0000,,Water is important.
Dialogue: 0,0:08:35.67,0:08:38.72,Default,,0000,0000,0000,,Since water is stuck together\Nwith a polar covalent bond,
Dialogue: 0,0:08:38.72,0:08:40.72,Default,,0000,0000,0000,,the hydrogen bit of it is a\Nlittle bit positively-charged
Dialogue: 0,0:08:40.72,0:08:43.01,Default,,0000,0000,0000,,and the oxygen is a\Nlittle negatively-charged.
Dialogue: 0,0:08:43.01,0:08:44.98,Default,,0000,0000,0000,,When water molecules move around,
Dialogue: 0,0:08:44.98,0:08:47.26,Default,,0000,0000,0000,,they actually stick together a little bit,
Dialogue: 0,0:08:47.26,0:08:48.82,Default,,0000,0000,0000,,hydrogen side to oxygen side.
Dialogue: 0,0:08:48.82,0:08:51.22,Default,,0000,0000,0000,,This kind of bonding happens\Nin all sorts of molecules,
Dialogue: 0,0:08:51.22,0:08:52.65,Default,,0000,0000,0000,,particularly in proteins.
Dialogue: 0,0:08:52.65,0:08:54.46,Default,,0000,0000,0000,,It plays an extremely important role
Dialogue: 0,0:08:54.46,0:08:57.05,Default,,0000,0000,0000,,in how proteins fold up to do their jobs.
Dialogue: 0,0:08:57.05,0:08:57.98,Default,,0000,0000,0000,,It's important to note here,
Dialogue: 0,0:08:57.98,0:09:01.52,Default,,0000,0000,0000,,bonds, even when they're written\Nwith dashes or solid lines,
Dialogue: 0,0:09:01.52,0:09:04.71,Default,,0000,0000,0000,,or no lines at all, are\Nnot the same strength.
Dialogue: 0,0:09:04.71,0:09:07.29,Default,,0000,0000,0000,,Sometimes ionic bonds are\Nstronger than covalent bonds,
Dialogue: 0,0:09:07.29,0:09:08.96,Default,,0000,0000,0000,,though that's the exception\Nrather than the rule,
Dialogue: 0,0:09:08.96,0:09:11.63,Default,,0000,0000,0000,,and covalent bond strength varies hugely.
Dialogue: 0,0:09:11.63,0:09:13.79,Default,,0000,0000,0000,,The way that those bonds\Nget made and broken
Dialogue: 0,0:09:13.79,0:09:17.88,Default,,0000,0000,0000,,is intensely important to how\Nlife and our lives operate.
Dialogue: 0,0:09:17.88,0:09:20.96,Default,,0000,0000,0000,,Making and breaking bonds\Nis the key to life itself.
Dialogue: 0,0:09:20.96,0:09:24.21,Default,,0000,0000,0000,,It's also like if you were\Nto swallow some sodium metal,
Dialogue: 0,0:09:24.21,0:09:25.38,Default,,0000,0000,0000,,the key to death.
Dialogue: 0,0:09:25.38,0:09:27.39,Default,,0000,0000,0000,,Keep all of this in mind as\Nyou move forward in biology.
Dialogue: 0,0:09:27.39,0:09:30.17,Default,,0000,0000,0000,,Even the hottest person you have ever met
Dialogue: 0,0:09:30.17,0:09:32.63,Default,,0000,0000,0000,,is just a bunch of\Nchemicals rambling around
Dialogue: 0,0:09:32.63,0:09:34.26,Default,,0000,0000,0000,,in a bag of water.
Dialogue: 0,0:09:34.26,0:09:35.84,Default,,0000,0000,0000,,That, among many other things,
Dialogue: 0,0:09:35.84,0:09:37.70,Default,,0000,0000,0000,,is what we're gonna talk about next time.