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Carbon as a building block of life | Properties of carbon | Biology | Khan Academy

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you're probably already familiar with some forms of carbon for example this graph I read a year this is one form carbon takes very important when you're riding with a pencil otherwise would not in your writing if you did have the graphite gets creeping onto your gripping onto your paper which you and your paper is also it's not pure carbon but has a lot a carbon in it this right over year is a raw diamond another form the carbon can take under intense time on after a long period of time under intense pressure bought you may or may not realize is that carbon is actually essential for life in fact life as we know it is carbon-based so carbon-based based life when we look for signs of life at least life as we know no other plans were looking for signs of carbon-based life and there might be other forms other other elements that form the backbone of life but carbon is the only one that we have been able to observe now wide is carbon so valuable for life what is a form the backbone above the molecules that make life possible what all comes down to where it sits in the periodic table and how many and its atomic number and how it tends to bond with things so this is why chemistry is important so carbon we ever we see over here has an atomic number six which by definition means it has 6 protons so far and writes nucleus that would have won to 3 for 56 protons and the most common isotope of carbon on earth is carbon 12 was also a six neutrons let me draw that in this nucleus one to 3 the 456 neutrons and then neutral carbon going to have six electrons and so to have them are going to be in there in a most in the first shell so there's two of them right over there the these are the these are the inner shell I guess you could say you're the so that's the first two electrons and then you have four remaining in its outermost shell and these four considered valence electrons these are the electrons that actually do the reacting and if any of this seems unfamiliar to you encourage you to watch the videos on Khan Academy on things like valence electrons but this is a little bit overview right over here carbon has four valence electrons in valence electrons are the ones that do or that tend to do they're reacting and so I could if I want to simplify this drying overreacted okay carbon and if our registrar to valence electrons which is a typical thing to do at its current as one to 3 for valence electrons now you might remember the octet rule that that Adams tend to be more stable when the brew at least pretend like they with that they're sharing or that they have eight electrons in there outermost shell it so carbon can do that by forming 4 coleville in bonds for example I could do that with hydrogens decided over here has one built like to read actually has one electron now the hydrogen feels good it feels like a cherry two-electron spilling its its its first shell hires is trying to fill out the first shell feel a little bit more like helium and others carmen says on I get to share this electron the carbon can do it again with another hydrogen it can do it again with a another hydrogen and it can do it again with another hydrogen so now carbon can feel like a I'm sharing eight electrons and the key to the hydrogens be like oh look you know I I'm sharing two electrons everyone seems to be happy everyone seems to be stable and this molecule right over here this is methane this is a methane and by definition because it involves carbon it is considered an organic molecule it is considered an organic molecule in fact the whole the whole field of organic chemistry is all about studying organic molecules which are molecules that have carbon now because this only has carbon and hydrogen in it is also considered to be a hydrocarbon hydrocarbon hydrocarbon and you might be familiar with things like like gasoline being considered a hydrocarbon and it is indeed a hydrocarbon in fact gasoline gasoline actually even even methane could be used as fuel right over here but it in typically continues long chains of hydrocarbons for example you could have 8 carbons form octane you might be familiar things like high octane fuel Scotti Carbin to the re for 5 6 serve in 8 this is a hydrocarbon its Oct aimed as 8 carbon Oct octane in every all the other bonds remember carbon forms for bonds are typically forms for bonds so now that carbon is for bonds now this car been has for bonds now this carbon to have them to hydrogen 2012 carbon 22 hydrogen 22 carbon hopefully the stars to give in appreciation why carbon is so useful as a building block because the conform so many bonds with so many different structures and these hydrocarbons they can be chains are they can even form they can even four rings they conform cycles alien beings like graphite and diamond carbons conform these latter structures where you know carbon is for is bonding carbon is forming is bonding to more than two carbons in these three dimensional shapes in these three in these three dimensional shapes and the shape because it's forming three bonds that that carbon typically forms bond in these are called tetrahedral shapes or tetrahedral bonding it with someone says tetrahedron if someone testers tetrahedron they're talking about they're talking about a their I'm it is a different color so a tetrahedron is a three-dimensional on three-dimensional shape that has four sides each of which are triangles each year which are triangles it so it would look like this you commute is a pyramid with the triangular base appear above the triangular base and when carbon forms bonds us in the case have this met the right over here under the carbon in the middle is this as this is this yellow circle then each of the hydrogens over here are going to be at the corners or they guess you see the vertices above the tetrahedron and so this is the tetrahedral shape that carbon is actually for me of course you have these Korie Lynn bond right over here we do this in this different color you have these call valence bond over here and we could write like this we could draw these coleville in bonds like this that's 10 home maybe that this one over here this one over here is right over here these electrons world is buzzing around in the one over here and then you have one over here so you might see methane sometimes a strong like this you might just see a drawn you might just see it drawn like this but it's really forming it's really for me a tetrahedral who a tetrahedral shape me finished writing it so hydrogen hydrogen hydrogen hydrogen were each of these lines represent a pair of electrons here eight electrons being shared an aggregate but the actual shape is closer to this now I'm claiming to you that it's the backbone I love life or life as we know it AZT any it even the back wall above life is as you are lol life in the former love you we've already talked about you being a majority water and that's why if you look at the average human being is the average human being is going to be roughly depends on how much how hot well hydrated you are in used a development the average human being is going to be sixty-five percent oxygen by massive cocks in your motyar two-thirds oxygen that's because I followed the water waters h2o and oxygen forms the bulk of the mass the water molecule but in second place come carbon in second place comes carbon carbon is approximately 18 percent %uh your body's mass and this is because everything but the non the the non fluid parthenon liquid part of your body it there's a lotta carbon going on there this writer is a DNA molecule and so this little diesel grey areas this is all carbon this right over here this right over here is hex ok I dais I'm not going to go into the details about what it does but hex ok I neice is a protein XO kind ace and the teal colored the you see there that is all carbon that's all carbon this right over here is a glucose did very sweet important way to regulate your body's energy and the teal color that is carbon this is ATP often considered to be the the molecular currency have energy in your body and all the teal there this is carbon this is why as a lot especially the non water part of your body is carmine so hopefully this gives you a better appreciation for carbon it's not just you fall for pencils and diamonds but even if you're just looking at your hand you're looking at a lot have carbon

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Duration: 9 minutes and 2 seconds
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Posted by: jake.goldwasser on Nov 19, 2015

Carbon as a building block of life.
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