 Hey everybody, Dr. O here. So we just got on talking about ionic bonds, which are caused by or created by a transfer of electrons. Now we're going to talk about covalent bonds. They're created by a sharing of electrons. So I mean, it's a mutually beneficial relationship. These two covalently bonded atoms are intimately connected, which is why these bonds are going to be stronger than ionic bonds. Really good analogy from the book talks about next door neighbors whose kids go to one house and play and then come back to the other house and play. They're not, I'm not giving up Oliver when he goes to the neighbor's house to play and they're not giving up their kids when they come here to play because they're going to go back and forth. So the sharing of electrons, the cycling back and forth is what makes covalent bonds so strong. Now, why do we care about them in human anatomy and physiology? They're very important in a lot of your organic compounds like your carbohydrates. For example, peptide bonds, which holds amino acids together in proteins. Those are going to be a type of covalent bonds. So very, very important. All right. So here you see you can have single, double, you can even have triple covalent bonds. So if two atoms are sharing one pair of electrons, they have a single covalent bond. If two atoms are sharing two pairs of electrons, they would have double. Here we see on the bottom that carbon is actually has double covalent bonds with two different oxygens there to form CO2, carbon dioxide. But you can even have triple covalent bonds where two atoms are sharing three pairs of electrons. But the key there is the sharing. So how many electrons are they sharing, that's what determines the type of covalent bond you have. Another very, very important thing to keep in mind when it comes to covalent bonds is we have nonpolar and polar covalent bonds. So whatever analogy you want to use with a nonpolar covalent bond, the sharing of electrons is equal. So think about maybe like a teeter tot or maybe you call it a seesaw. Two people of the exact same weight, they're sharing the load equally so it's balanced. But if one person is much heavier than the other person, there's going to be an imbalance there. My favorite example with polar covalent bonds would be tug of war. So let's talk about polar covalent bonds. It's when the sharing is unequal. So you see here at the bottom methane would be nonpolar covalent bonds because their, the sharing of electrons is equal. Water is going to have polar covalent bonds because the sharing is unequal. So if you look at, so like the oxygen has that partial, that's a little, that little symbol is delta. That means partial negative. So oxygen has a partial negative charge, meaning the electrons are spending more time near oxygen than they are hydrogen, which is why hydrogen has a partial positive charge. So if you want to use, so oxygen has eight positive protons pulling these negative electrons towards it. Hydrogen only has one positive proton, weakly pulling the electrons towards it. That's why the electrons, they stir, they're still shared, but they spend more time with oxygen. So if you want to go back to your teeter totter example, oxygen eight times heavier than hydrogen. It's very unevenly balanced or a tug of war. If I'm eight times the size of my kid and we're in a tug of war, I'm going to win easily. I'm going to pull and pull and pull and the electrons are going to travel my direction. So that's why I like that tug of war analogy. You have two people exact same size mass strength in a tug of war. It's going to be a battle back and forth. That would be a nonpolar covalent bond. Me having a tug of war with my five year old Oliver, that's going to be a polar covalent bond. I'm going to win almost all the time. So I'm going to get the electrons more often than not. Another example here would be hydrogen chloride. So chlorine has 17 protons, hydrogen has one. So the negative electrons are going to be way more attracted to the chlorine side of this bond. So yes, they're still sharing, but hydrogen is going to have the partial positive end because the negative electrons are being pulled away from it more often than not. Chlorine's going to have the partial negative end. So this matters. This is going to matter very much in our next video where we talk about hydrogen bonds because these partial positive and negative charges will determine how a compound interacts with its neighbors. And just so you know, the reason they're called partial positive and negative charges is because these forces, they're not as strong as an actual ionic bond. So that's why they're called partial positive or partial negative. Okay. So that's going to be your covalent bonds, both nonpolar and polar. I hope this helps. Have a wonderful day. Be blessed.