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Carbon… SO SIMPLE: Crash Course Biology #1

October 16, 2019

If you’re wondering, this is how the most revolutionary course in biology of all time begins. Come today to learn about covalent and ionic and hydrogen bonds. What about electron orbitals, and the octet rule and what does it all have to do with a madman named Gilbert Louis? It’s all contained within. [Intro theme plays] Hello! I’m Hank. I assume you’re here because you’re interested in biology, and if you are, that makes sense because like any
good 50 Cent song- biology is just about sex, and not dying. Everyone watching this should be interested in sex and not dying, being that you are, I assume, a human being. I’m going to be teaching this biology course differently than most courses you’ve ever taken in your life, for example, i’m not going to spend the first class talking about how I’m going to spend the rest of the class. I’m just going to start teaching you, like right about now… I may say one more thing before I start
teaching. Yes, I am going to. It’s that, um, if I’m going too fast for you- great thing about YouTube is that you
can just rewind, watch stuff over and over again if it’s confusing and
hopefully it will become less confusing. And you’re even allowed to fast forward through the bits that you already know. Another tip, you can actually even use the number keys on your keyboard to move around in the video, and I promise, you can do this to me as much as you want and I’m totally not gonna mind. A great professor of mine once told me that in order to really understand any topic you have to understand a little bit of the level of complexity just below that topic. The level of complexity just below biology is chemistry. Unless you’re a biochemist in which case you would argue that it’s biochemistry. Either way, we’re going to have to know a little bit of chemistry in order to get through biology. So that, my friends, is where we’re gonna start. I am a collection of organic molecules
called Hank Green. Organic compounds are a class of compounds that contain carbon. And carbon is this sexy little minx in the periodic table (Oh lala) that’s, you know, disinterested in monogamy. Jezebel? Bit of a tramp. Hussy? When I say carbon is small I mean that it’s actually, you know, as an atom, it’s a relatively small atom. It has 6 protons and 6 neutrons for a total atomic weight of 12. Because of that carbon doesn’t take up a lot of space. And so carbon form itself into weird rings, and sheets, and spirals, and double, and even triple bonds. It can do all sorts of things that could never be accomplished by more bulky atoms. It’s basically, you know, your atomic equivalent of an Olympic gymnast. It can only do all of those wonderful beautiful elegant things because it’s kinda tiny. I also said that carbon is kind, and that’s an interesting sort of thing to say about an atom. It’s not like some other atoms that are desperately trying to do anything they can to fill up their electron orbitals. No, carbon knows what it’s like to be alone and so it’s not all please-I’ll-do-anything-for-your-electrons needy like fluorine, or chlorine, or sodium is. Elements like chlorine, if you breathe them in they like literally tear up your insides, And sodium, sodium is insane! If you like put it in water it explodes! Carbon though, meh. It wants more electrons but it’s not gonna like kill to get them. It makes and breaks bonds like a 13 year old mall rat and it doesn’t even hold a grudge. Carbon is also, as I mentioned before, a bit of a tramp because it needs 4 extra electrons and so it’ll bond with pretty much whoever happens to be nearby. And also because it needs 4 electrons, it’ll bond with 2, or 3, or even 4 of those things at the same time. And carbon is willing and interested to bond with lots of different molecules like hydrogen, oxygen, phosphorous, nitrogen, or to other molecules of carbon. It can do this in infinite configurations allowing it to be the core atom of complicated structures that make living things like ourselves. Because carbon is this perfect mix of small, kind, and a little bit trampy, life is entirely based on this element. Carbon is the foundation of biology. It’s so fundamental that scientists have a pretty difficult time even conceiving of life that isn’t based on carbon. Life is only possible on Earth because carbon is always floating around in our atmosphere in the form of carbon dioxide. So it’s important to note, when I talk about carbon bonding with other elements, I’m not actually talking about sex, it’s just a useful analogy. Carbon on its own, is an atom with 6 protons, 6 neutrons, and 6 electrons. Atoms have electron shells and they need to have these shells filled in order to be happy fulfilled atoms. So carbon has 6 total electrons- 2 for the first shell so it’s totally happy, and 4 of the 8 it needs to fill the second shell. Carbon forms that have a bond that we call covalent this is when atoms actually are sharing electrons with each other. So in the case of methane, which is pretty much the simplest carbon compound ever, carbon is sharing its 4 electrons in its outer electron shell with four atoms of hydrogen. Hydrogen atoms only have one electron so they want their first S orbital filled. Carbon shares its 4 electrons with
those 4 hydrogens, and those 4 hydrogens each share 1 electron with carbon so everybody’s happy. In chemistry and biology this is often
represented by what we call Lewis Dot Structures. [theme music] Good lord I’m in a chair. I’m in a chair and there’s a book. Apparently I have something to tell you that’s in this book, which is a book called Lewis: Acids and Bases by Hank Green. Gilbert Louis, the guy who thought up Lewis Dot Structures, was also the guy behind Lewis Acids and Bases. And he was nominated for the Nobel Prize 35 times. This is more nominations than anyone
else ever in history, and the number of times he won, was roughly the same number of times that everyone else in the world has won, which is 0. Lewis disliked this a great deal. It’s kind of like a baseball player having more hits than any other player in history and no home runs. He may have been the most influential chemist of all time. He coined the term photon, he
revolutionized how we think about acids and bases, and he produced the first molecule of heavy water, and he was the first person to conceptualize the covalent bond that we’re talking about right now. Gilbert lewis died alone in his laboratory while working on cyanide compounds after having had lunch with a younger more charismatic colleague who had won the nobel prize and who worked on the Manhattan Project. Many suspect that he killed himself, with the cyanide compounds that he was working on, but the medical examiner said heart attack without really looking into it. I told you all that because, uh, the little Lewis Dot Structure that we use to represent how atoms bond to each other is something that was created by a troubled, mad genius. It’s not some abstract scientific thing that’s always existed, it’s a tool that was thought up by a guy and it was so useful that we’ve been using it ever since. In biology, most compounds can be displayed in Lewis Dot Structure form, and here’s how that works: these structures basically show how atoms bond together to make up molecules and one of the rules of thumb when making these diagrams is that the elements that were working with here react with one another in such a way that each atom ends up with eight electrons in its outermost shell. That is called the octet rule: because atoms want to complete their octets of electrons to be happy and satisfied. Oxygen has 6 electrons in an octet and needs 2 which is why we get H2O. It can also bond with carbon which needs 4 so you get 2 double bonds to 2 different oxygen atoms and you end up with CO2: that pesky global warming gas, and also the stuff that makes all life on Earth possible. Nitrogen has five electrons in its outer shell. Here’s how we count them: there are 4 placeholders- each of them wants 2 atoms and like people getting on a bus, they prefer to start out not sitting next to each other. I’m not kidding about this they really don’t double up until they have to. So for maximum happiness, nitrogen bonds with 3 hydrogens, forming ammonia or with 2 hydrogens sticking off another group of atoms which we call an amino group. And if that amino group is bonded to a carbon that is bonded to a carboxylic acid group then you have an amino acid. You’ve heard of those right? Sometimes electrons are shared equally within a covalent bond like with O2. That’s called a non-polar covalent bond. But often one of the participants is more greedy. In water, for example, the oxygen molecules sucks the electrons in and they spend more time with the oxygen than with the hydrogens. This creates a slight positive charge around the hydrogens and a slight negative charge around the oxygen. When something has a charge we say that it’s polar. It has a positive and negative pole and so it’s a polar covalent bond. Now let’s talk for a moment about a completely different type of bond: which is an ionic bond. And that’s when instead of sharing electrons, atoms just completely, wholeheartedly donate or accept an electron from another atom and then live happily as a charged atom. And there actually is no such thing as a charged atom- if an atom has a charge, its an ion. Atoms in general prefer to be neutral, But compared with having a full octet, it’s not that big of a deal. Just like we often choose between being emotionally balanced and sexually satisfied, atoms will sometimes make sacrifices for that octet. The most common ionic compound in our daily lives is salt. Sodium chloride, NaCl. This stuff despite its, deliciousness, as I mentioned previously, is made up of two really nasty chemicals: sodium and chlorine. Chlorine is what we call a halogen which is an element that only needs 1 electron to fulfill its octet, and sodium is an alkaline metal which means that it only has 1 electron in its octet. So chlorine and sodium are so close to being satisfied that they will happily destroy anything in their path in order to fulfill their octet. And thus there’s actually no better outcome than just to get chlorine and sodium together and have them loving on each other. They immediately transfer their electrons so that sodium doesn’t have its one extra and chlorine fills its octet. They become Na+ and Cl- and are so charged that they stick together and we call that stickiness an ionic bond. And just like if you have to really crazy friends it might be good to get them together so that they’ll stop bothering you, same thing works with sodium and chlorine. You get those two together and they’ll bother no one, and suddenly they don’t want to destroy, they just want to be delicious. Chemical changes like this are a big
freaking deal remember chlorine and sodium just a second ago were definitely killing you and now they’re tasty. Now we are coming to the last bond that we are going to discuss in our intro to chemistry here and that’s the hydrogen bond. I imagine that you remember water, I hope that you didn’t forget water. Since water is stuck together in a polar covalent bond, the hydrogen bit is positively charged and the oxygen bit is negatively charged. So when water molecules are moving around we generally think of them as a perfect fluid but they actually stick together a little bit: hydrogen-side to oxygen-side. You can actually see this with your eyes if you fill up a glass of water too full it will bubble at the top- the water will stick together at the top. That’s the polar covalent bonds sticking the water molecules to each other so that they don’t flow right over the top of the glass. These relatively weak hydrogen bonds happen in all sorts of chemical compounds they don’t just happen in water and they can actually play an extremely important role in proteins which are the chemicals that pretty much make up our entire bodies. A final thing to note here is that bonds, even covalent bonds, ionic bonds, even with their own class, are often much different strengths and we you know tend to just write them with a little line but that line can represent a very very strong covalent bond or a relatively weak covalent bond. Sometimes ionic bonds are stronger than covalent bonds though that’s generally not the case and the strength of covalent bonds varies wildly. How these bonds are made and broken is intensely important to life and to our lives. Making and breaking bonds is in fact the key to life itself- and like also the key to death, for example if you were to ingest some sodium metal. Keep this in mind as we move forward through biology, even the sexiest person you have ever met in your life is just a collection of organic compounds rambling around in a sack of water. Review Time! Now we have the Table of Contents which I know is supposed to come at the beginning of things but we are revolutionary here we’re doing it different. So you can click on any of the things here and you can go back and review what you learned, or didn’t learn. And if you have questions please-please please please-please please please ask them in the comments and we’ll be down there answering them for you. So, thank you for joining us it was a pleasure- it was a pleasure working with you today.


  • Reply Hannah Hagen June 16, 2019 at 4:11 am

    2x speed: the only way to watch crash course.

  • Reply Lone Wolf June 17, 2019 at 5:39 am

    I get the feeling his previous video was about a plant that is gradually becoming legal again…

  • Reply U-Played Ur-Self June 17, 2019 at 11:04 pm

    Who’s studying before regents

  • Reply Jane Whitsell June 19, 2019 at 12:12 am

    So, I’m in college for my BS in Environmental Science. I may have accidentally signed up for the biology class first (okay, I did, not may have lol). I don’t really remember a whole lot from school in regards to science/chemistry/Biology. Do I need to take a chemistry class before I can take a biology class?! Can I pay you to tutor me?! 🤣🤷‍♀️

  • Reply Pan_ Kiddo June 20, 2019 at 8:23 am

    Y’all I’m watching this at 3:30am during the summer cause of how worried I am for my upcoming freshmen year 😂

  • Reply Courtesy bog3 June 20, 2019 at 1:21 pm

    This helped me with my gsce thank you so much i wish i had some money to shovel at you

  • Reply Jonathan Cipriano June 20, 2019 at 10:17 pm


  • Reply Aaren Arasaratnam June 21, 2019 at 12:35 am

    well this was a weird video

  • Reply Potpot Patpat June 22, 2019 at 9:48 am

    Hi.. I have a question. Is the theory of evolution is proven?

  • Reply TehRainbowNoob June 24, 2019 at 7:27 pm

    What's the difference between ionic and polar bonds

  • Reply Cate Rehm June 25, 2019 at 2:02 am

    Hank! I didn’t recognize you!

  • Reply Paul lazo June 25, 2019 at 5:42 am

    So boring,not well explained

  • Reply The Daily Digestion June 27, 2019 at 10:30 pm

    i love this!!! thank you!!!!

  • Reply Tim Wigglesworth June 30, 2019 at 5:03 am

    Wow I think u might save me, I have 24hrs to study year 11 and 12 bio and first sem uni for an exam and ur actually interesting to watch

  • Reply Corey Roberts-Reynolds June 30, 2019 at 5:46 am

    Could you please explain the idea behind (-)–negative and (+)–positive charges. What exactly does negative and positive refer to, and why do we use the word negative and positive in this context?

  • Reply Qwertyuoip 123 June 30, 2019 at 7:12 am



  • Reply Ruby Rose Vella July 1, 2019 at 3:21 pm

    These videos are getting me through studying for a dense and brain destroying test that is the mcat.

  • Reply Razer Hawk July 3, 2019 at 3:12 pm

    reminds me of pewdiepie

  • Reply bugs are special July 3, 2019 at 6:09 pm

    this teachear makes me want to study

  • Reply Get outta here! July 3, 2019 at 6:24 pm

    Are all the crash course guys related to each other

  • Reply Peter Vautier July 6, 2019 at 10:00 pm

    So what happens if I throw a lump of sodium into some chlorine?

  • Reply zakman 209 July 7, 2019 at 8:02 am

    Please make a video on DNA translation, transcription and Genetic codes

  • Reply Boa Hancock July 9, 2019 at 7:16 pm

    omg my dad heard the word s*x and he flew out of he kitchen

  • Reply Sama Saber July 10, 2019 at 10:29 am

    10:31 it looks like Mickey mouses

  • Reply CoderOf21 July 10, 2019 at 10:30 pm

    Its not a biology course its an evolution course, that tries to convent us that evolution is the truth and explain everything. take care of that everybody

  • Reply Skarleth Araica July 12, 2019 at 10:06 am

    Estoy muy feliz que este subtitulado en diferentes idiomas, aún no puedo seguir el ritmo totalmente en inglés.
    Actualmente soy estudiante de biología y, me alegra saber que estaba en lo correcto al decidir estudiar en conjunto química de manera autodidacta, ya que es fundamental para entender biología.

  • Reply Henki July 12, 2019 at 6:46 pm

    Biology: Sex and not dying

  • Reply Caboose 0417 July 13, 2019 at 4:25 am

    Silicon based orginisms do exist on earth

  • Reply Karen Rapoport July 14, 2019 at 12:34 am

    "They don't want to destroy, they just want to be delicious". We should all strive for a life like salt

  • Reply BRIGHTER harrison July 14, 2019 at 1:06 am

    Me trying to find the derivative of a polynomial and listening to the first 45 seconds of this video.

    "why is he talking about 50 cent…. wtf is he talking about.

  • Reply diego delgado July 17, 2019 at 1:04 am

    This guy is either drunk or high af, but such a good teacher

  • Reply Kathleen Elizabeth Thompson July 19, 2019 at 12:01 pm

    hey, 2019 here… this is a super slow Hank compared to the other Videos xD. Come on ADD/ADHD, kick in with the rest of the world! lolz

  • Reply Phonic Tales July 19, 2019 at 7:28 pm

    Thank you

  • Reply Tourmelion July 21, 2019 at 7:07 pm

    0:32 I wanted to revise with my dad near and heard this 😳

  • Reply Tarq's Picks July 22, 2019 at 1:23 am

    I felt it could have been more clear on why some atoms share electrons and some don't, and how combining certain atoms (hydrogen and water, for example) satisfies the octave of the hydrogen atom even though it still only has two electrons.

  • Reply KipperBill July 25, 2019 at 7:59 am

    I hope to see you at this year's YouTube rewind

  • Reply Łiz NSS July 26, 2019 at 6:11 pm

    8:31 I thought it said "Iconic Bonds"

  • Reply Kaya Malalgoda Weerakoon July 27, 2019 at 8:57 am

    did they change the title of the video?

  • Reply Duaa Elsayed July 30, 2019 at 10:44 pm

    Kind of glad that I know this all from my igcse gell

  • Reply Christopher Magee August 1, 2019 at 6:44 pm

    That goatee…

  • Reply Alex Baldwin August 1, 2019 at 7:37 pm

    “I hope you’re interested in sex and not dying… ya know, like normal people.”

    Ace people: 😐😐😐

  • Reply Stone Johnson Vlogs August 3, 2019 at 6:22 am

    My AP Bio teacher took an ENTIRE week to teach us this… and you (a drunk man) taught it to me in 12 minutes!! Amazing

  • Reply duckbilledmonfrogga August 3, 2019 at 2:16 pm

    It's been 22 years since nursing school. I'm an LVN. My sciences are way out of date. I'd have to take them all again for the RN program. I feel like I need a real edge to keep ahead of the game, once I start, again. So thankful for you.

  • Reply oh August 3, 2019 at 4:33 pm

    i'm at the in between of 6th and 7th and i just want to learn biology and what not, everything i learned in 6th grade science was penguins, cool math, and the solar system. did i mention we were stuck on solar systems for 2-3 school years? i hate american schools.

  • Reply Kit 22 August 8, 2019 at 10:24 pm

    I'm really smart but I've failed…… A lot of school . This gives me hope that I could pass these classes one day

  • Reply Aman Goel August 9, 2019 at 1:35 am

    This dude sounds like a virgin lol, but I like CrashCourse

  • Reply Alice Von Manstein August 9, 2019 at 11:00 am


  • Reply Bing Ding Ernestine Koo August 9, 2019 at 1:20 pm

    I dont understand . Someone please explain?

  • Reply Kamal Kamil August 11, 2019 at 6:26 pm

    Will they teach us this in college?

  • Reply orangefishblood August 14, 2019 at 5:38 pm

    he talked about sex way to much lol

  • Reply ShannenMakesVideos August 17, 2019 at 5:50 am

    Hank is handsome. Just dropping that here as a reminder.

  • Reply Flavie GARAMPON August 17, 2019 at 9:31 am

    It was really fun to watch this video and also intresting 🙂

  • Reply Patrick Smith August 19, 2019 at 9:05 am


  • Reply sillystuffandnonsense August 19, 2019 at 11:15 pm

    AP bio gang where you guys at

  • Reply Zaya Moone August 20, 2019 at 4:55 pm

    Why does he remind me of Klaus Hargreeves

  • Reply Alex WF August 22, 2019 at 2:23 am

    I came here for a quick biology preview before the school year but instead ended up learning more chemistry then I did in the entire year last year.

  • Reply Xochitl Rose August 23, 2019 at 5:09 am

    You're freaking hilarious. I love all your videos. Clarification in 15 mins flat! perfection.

  • Reply Don't, Jimm August 24, 2019 at 3:20 pm

    Poor guy…..

  • Reply ImpacT August 27, 2019 at 9:15 pm

    So carbon is a prostitute…

  • Reply Cat loomer☆ August 28, 2019 at 9:17 am

    Hank, you was,are and will be THE BEST collesction of organic compunds everr!!!!!

  • Reply Xeta August 28, 2019 at 10:12 am

    so you are telling me carbon atoms are basically sluts, and life is made from sluts? well that makes sense then

  • Reply Elizabeth Mahler August 29, 2019 at 9:29 pm

    Is his book “Lewis: Acids and Bases” able to be purchased anywhere?
    I did a quick google search and didn’t find anything about it

  • Reply 한동현 August 30, 2019 at 7:17 am

    Can you make a Korean subtitle please? Your videos are interesting

  • Reply Ingride Cruz August 30, 2019 at 4:15 pm

    i was getting annoyed by the promiscuous woman exemplification but then i saw this video was made in 2012 and it was dark times in gender and sexual debates (still is, but anyway). So i'll let it pass.

  • Reply Anthony Varriale August 31, 2019 at 12:39 am

    I'm here because my high school biology teacher just started off with organic compounds and didn't tell us about any of this. I was so confused until I came here. Thank you!

  • Reply El Gallo August 31, 2019 at 2:08 pm

    Hank's facial hair and over the top focus on edginess and describing carbon as a "tramp" really threw me off at first. But from an educational perspective, this is one of the most insightful crash course videos I've watched.

  • Reply Michelle Wu August 31, 2019 at 9:23 pm

    So you mean… carbon is just Henry Montague?

  • Reply Rickmeister September 3, 2019 at 11:27 pm

    thank god, my teacher gets too general sometimes but with crash course i am unstoppable

  • Reply LL Pan September 5, 2019 at 1:14 am

    Question: does atom has to do with some of this

  • Reply SemiPro Student September 6, 2019 at 3:41 pm

    Carbon is the pornstar with the heart of gold. Papa bless

  • Reply Aboubaker Hassan September 7, 2019 at 5:24 pm

    Goatee Hank is the best Hank 🤟🏼

  • Reply Jason Lee September 8, 2019 at 2:28 pm

    I don’t understand the sharing of electrons, Covalent bonds share them but doesn’t ionic bonds share them too?

  • Reply amber brooke September 10, 2019 at 1:50 am

    So are only covalent bonds represented through the lewis structure, or does the lewis structure also show ionic and hydrogen bonds as well?

  • Reply Romulo B. Batucol September 10, 2019 at 4:05 pm

    I need the subtitle so i don't need to watch every time i have to remember something. It would be easier and very helpful if there is a written copy of everything you are saying sir Hank G. Thank you.

  • Reply Keira TheYouTuber September 11, 2019 at 3:38 pm

    I'm a college student and this man teaches me better than my professor. We just write notes everyday and there is no hype class discussions.

  • Reply Nat Brown September 12, 2019 at 5:46 am

    Literally, JUST now (at 34), learned you can rewind/fast-forward using the number keys!

  • Reply Polarx Prism September 13, 2019 at 9:13 pm

    Omg wow Crash Course was kind of gross back then, nowadays you don’t hear anything about sex or like anything like that.

  • Reply Mozart jams September 14, 2019 at 5:39 pm

    0:33 – 0:42 MY biology teacher be like

  • Reply Paul McKinney September 16, 2019 at 6:02 am

    Hank is funny I'd be cool to meet him , I like this channel so much.

  • Reply ramblingboots September 16, 2019 at 7:34 am

    Loving the goatee, Hank!

  • Reply Menglong Youk September 16, 2019 at 2:25 pm

    Jesus Christ. The story of Lewis is pretty depressing.

  • Reply Deanna Flores September 16, 2019 at 10:59 pm

    aside from being super helpful he is hilarious!! I wish i was as smart as him !!

  • Reply Rose Poetry September 20, 2019 at 1:53 am

    Ahhh young Hank 💚

  • Reply Kayla Tharp September 21, 2019 at 9:04 pm

    When he teaches you more than your biology teacher does 😍

  • Reply The Ghost Of gaming September 23, 2019 at 12:41 am

    Can some one in detail(in a way I can understand)explain to me what is a hydrogen bond

  • Reply Edward Scharff September 24, 2019 at 11:59 am

    i actualy understand this guy

  • Reply Gersh Klein September 24, 2019 at 2:18 pm

    Carbon's a tramp😂

  • Reply Aaron Boys September 25, 2019 at 6:33 pm

    So was Wu-Tang talking about the processes of Carbon when they made their song "Can it All Be So Simple?"

  • Reply Player NoobMin September 28, 2019 at 3:23 pm

    This episode explains the whole first semester of my senior year on STEM. Hats to you CC team and bearded Hank (should've watched this instead).

  • Reply Nate Weinand September 29, 2019 at 6:42 pm

    For context sake: I just started re-watching this.
    Am I going crazy or did this video have a different title before? Something like “Why Carbon is a Tramp”?

  • Reply Abran Cullen October 3, 2019 at 9:45 am

    so in summary, biology is sex and not dying

  • Reply Eirik Guttulsrud October 3, 2019 at 5:10 pm

    Lewisˋs Asses and Basses. I canˋt unhear it…

  • Reply M- October 4, 2019 at 10:02 am

    henlo to y'all filipinos out thereee who's cramming for the upcat? luv y'all

  • Reply FrostenZ October 4, 2019 at 12:11 pm


  • Reply Leila Andrews October 6, 2019 at 6:16 pm

    im really out here trying to be like Carbon

  • Reply MsLearox October 8, 2019 at 1:43 am

    i- am i the only one that could not follow with this lmfao

  • Reply RAIDING SIEG October 11, 2019 at 9:10 am

    you are way better than all boring school teachers

  • Reply agatworose October 12, 2019 at 11:52 am

    i'm studying biology just for fun in my second language, so can you! 😉

  • Reply gxld flower October 12, 2019 at 4:33 pm

    these are so fun to watch and so informative i very much appreciate

  • Reply JustZazzy October 15, 2019 at 11:25 am

    1rst 50 seconds: Disliked

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