in this video I'll show you how to draw the low structures of molecules molecules are calent compounds that consist of non-metals so here's an example first we're going to talk about bonding of molecules so the example that we'll look at is hydrogen combining with Florine here's hydrogen hydrogen is in group one and that's why it has only one veence electron which is shown here as one dot on the side Florine is in group seven and has total total of seven veence electrons here's the seven dots and when these two elements approach each other they form the molecule hydrogen fluoride and notice how the two single electrons are actually shared between both hydrogen and Florine so these shared electrons form a calent bond the other six electrons that remain in the Florine these two these two and these two are called longone pairs so there's two types of electrons in molecules there's shared electrons which are usually shown as a line so we can show shared electrons as two dots or as a line and then there's also lone pairs here in the table below are shown all the non-metals listed by group number here in this row I have the Lis structures for each element in this row we have the bonds here we have the lwn pairs and then examples so let's look at hydrogen hydrogen is in group one it has one veence electron burum is in group two it has two veence electrons Boron group three three valence electrons now remember that the single dots from these Lis structures actually tell us how many bonds these elements form when they react so since hydrogen has only one single dot it forms one bond meridium has two single dots it forms two bonds when it reacts boron has three dots single dots forms three bonds let's look at nitrogen nitrogen has five veence electrons three of them are single dots the other two are a l pair so nitrogen forms three bonds again because of the three single dots and one L pair oxygen has six veence electrons two are single dots and then the rest are long pairs that's why oxygen forms two bonds and two longone pairs so keeping that in mind let's do the following examples draw draw the electron dot formulas which is the same as L structures for the following molecules we have silicon Tetra fluoride Boron tribromide phosphorus triiodide dihydrogen monosulfide so when you draw these L structures the first thing you have to ask yourself is which atom goes in the center so I've actually underlined the central atoms in the first example silicon is Central so how do we know what goes in the center the single atom is the central atom so so since there's one silicon and four flines silicon is Central flines are the outer atoms so we place silicon in the center now look at the table that we just talked about silicon has four veence electrons it has four single dots that's why it forms four bonds and here's the four bonds on silicon and then Florine has only has seven veence electrons only one single dot it's going to form one single Bond so we connect the four bonds of silicon to the four flines and that's the lowest structure and don't forget to include the L pairs next example Boron tribromide Boron is the central atom because that's the single atom boron has three veence electrons so these are the three single bonds that connect to the outer atoms bromine and then each bromine carries three long pairs phosphorus next example phosphorus is the central atom because that's the single atom phosphorus has five veence electrons three of these are single dots so those are going to be shown as bonds and then the other two are the long pairs and then the last example hydrogen sulfur is in the center it forms two single bonds and it has two long pairs moving on to the next set of exercises uh sulfur is the single the central atom here so that goes in the center can it's attached to two flines oxygen is a central atom it's attached to two Iota groups phosphorus is a central atom attached to three outer atoms and there's a lum PA in the center now sometimes the central atom will have multiple bonds so there's a single Bond possible there's two bonds which is called a double bond or even three bonds which are triple bonds this is a single bond this is an example of a double bond and this is an example of a triple bond so in the molecule carbon dioxide you're going to use the same table same rules that we used before right carbon in the center that's the central atom oxygens are the outer atoms if you look at the number of veence electrons for carbon carbon has four veence electrons and it forms four bonds now since there's only two oxygens these bonds have to be double bonds so carbon has four bonds in this case it's two double bonds and there's no long pairs on carbon oxygen has two bonds and two long pairs each so the result is a carbon that's double bonded to each oxygen hcn which is called cyanic acid it's uh carbon is in the center it's triple bonded to nitrogen and it's single bonded to hydrogen and nitrogen carries a lone pair and here's a few more examples which illustrate the same thing that we just learned