[Music] hi and welcome back to freeze lessons by the end of this video you should be able to describe how electrons are shared in Cove valent bonding you should then be able to draw diagrams to show calent bonding with double and triple Cove valent Bonds in the last couple of videos we've been looking at small calent molecules we've seen the molecules hydrogen chlorine hydrogen chloride water ammonia and methane now all of these molecules have single calent bonds and remember that a single calent bond is a shared pair of electrons in this video we're going to look at three other small calent molecules however as you'll see these molecules have double or triple calent bonds let's start by looking at the calent bonding in an oxygen molecule an oxygen molecule has the formula O2 this tells us that the oxygen molecule contains two atoms of oxygen oxygen atoms have six electrons in the outer energy level and I'm showing you that here each oxygen atom requires two more electrons to achieve a full outer energy level they can do this by overlapping their outer energy levels like this now in this case we have two shared pairs of electrons scientists call this a double Cove valent Bond here are the dot and cross and stick diagrams for the oxygen molecule and you'll notice that in the stick diagram a calent bond is shown as two lines okay the next calent molecule is nitrogen the nitrogen molecu has the formula N2 so the nitrogen molecule contains two atoms of nitrogen as you can see nitrogen atoms have five electrons in the outer energy level I'd like you to draw the calent bonding in a nitrogen molecule so pause the video now and try this yourself okay each nitrogen atom requires three more electrons to achieve a full outer energy level they can do this by overlapping their outer energy levels like this now in this case we have three shared pairs of electrons and scientists call this a triple calent bond here are the dot and cross diagram and the stick diagram for the nitrogen molecule and notice that in the stick diagram a triple calent bond is shown as three lines okay we're going to finish Now by looking at carbon dioxide I should point out that carbon dioxide is not on the AQA specification but it is required for Ed XL students I'd recommend that AQA students do watch this as you could be asked to work out the structure in your exam okay the formula of carbon dioxide is CO2 so a molecule of carbon dioxide contains one atom of carbon and two atoms of oxygen a carbon atom has four electrons and its outer energy level so a carbon atom requires four more electrons to achieve a full outer energy level an oxygen atom has six electrons in its outer energy level so an oxygen atom requires two more electrons to achieve a full outer energy level in this case the carbon atom and the two oxygen atoms overlap the outer energy levels like this so the carbon atom forms a double Cove valent bond with one oxygen atom and a double calent bond with the other oxygen atom now the carbon atom and both the oxygen atoms each have a full outer energy level here are the dot and cross diagram and the stick diagram for the carbon dioxide molecule you'll find plenty of questions on this topic in my vision workbook which you can get by clicking on the link [Music] above