in today's video we're going to learn about the structure and properties of two allotropes of carbon diamond and graphite and we'll consider the other allotropes graphene and fullerenes in the next video first though you might be wondering what an allotrib is basically allotropes are different structural forms of the same element in the same physical state so if we consider carbon in this solid state it can take lots of different forms like diamond graphite or fullerenes so these are all different allotropes of carbon both diamond and graphite are giant covalent structures which means that they're made of a regular lattice of covalently bonded atoms which makes them both very strong in diamond each of the carbon atoms is curvently bonded to four other carbon atoms which is the maximum number of bonds that carbon can make this form is a regular 3d pattern which you're fortunately not going to have to draw but you do need to be able to recognize this sort of structure as each of these equivalent bonds is really strong it will take loads of energy to break them and so diamond itself is very strong and has a really high melting point however it doesn't conduct electricity because it has no free electrons or ions that could move around now let's compare these features of diamond to those of graphite first each carbon in graphite is bonded to only three other carbon atoms rather than four in the case of diamond second the atoms are arranged into hexagons that together form large flat sheets which are then arranged on top of one another to form lots of layers however these individual layers are only held together weakly as there are no current bonds between them this means that they're free to slide over one another which makes graphite relatively soft when compared to diamond that said graphite still has a very high melting point because the individual layers are strongly held together with covalent bonds now remember how earlier we said that carbon atoms can make four covalent bonds each but in graphite they only make three well that means that each carbon atom in graphite has one spare electron that is not using in bonding instead this electron becomes delocalized which basically means that it's free to move around and all of these free electrons allow the graphite to conduct electricity and heat before we finish it's worth mentioning that a single layer of graphite is known as graphene and scientists can actually isolate these individual layers and use them to make other structures such as spheres and tubes we call these structures and we explore how they work in the next video anyway that's everything for today if you enjoyed it then please do give us a like and subscribe and we'll see you next time