 Atomicity you write down the next property. What do you mean by atomicity atomicity of nitrogen is what the atomicity Of nitrogen is it is diatomic molecule, right and to write down Nitrogen is a diatomic molecule diatomic molecule It's bond order Because we know and to molecule exists like this Nitrogen has three one triple bond and one one loan to our next nitrogen. It has one sigma bond and Two pi two pi bond one sigma and two Okay, next line phosphorous arsenic antimony exist in phosphorus arsenic antimony Exist as not in exist as tetra atomic molecule tetra atomic molecule like p4 SB4 AS4 like that. Okay, right on these elements are not capable of forming multiple bond, okay cable of all the multiple bond Because of the large size of orbital Large size of orbital so p4 structure you see it has a tetrahedron structure where Exist or Place at the corner of a tetrahedron like this. This is a task Okay This angle is what this angle is 60 degree You know, yes, it's really p4. Can you tell me the valence electron in p4 molecule? Total valence electron In one phosphorus atom, how many valence electron we have 5 we have p4 5 into 4 so p4 has 20 valence electron Now we see the type of compounds that these element forms. Okay, right on next thing Chemical reactivity right down the heading chemical reactivity, okay The first type of compound that we are going to discuss here Is the hydrides the formation of hydrides, right down the elements of group 15 forms hydride of hydride of mh3 type m H3 type likely have NH3 Ph3 ASH3 SBH3 bih Okay, this type of hydride Okay, so all these hydrides has three bond pair and One load correct All of you know this right that's why the steric number is four and hybridization is what? SB3 hybridization is SB3 geometry and What is the geometry geometry tetrahedral shape shape is Triagonal pyramidal under what case geometry and shape will be same. Can you tell me anyone? When there are no lone pairs when there There is no lone pair present when the lone pair is zero then whatever the geometry we have That will be the shape of the molecule also right that you must take care of Okay. Now like I said hydrides they form these Type of hydrides now there are various properties of hydride which is very important Okay, and they usually ask questions from these only chemical reactivity hydrides hydrides ka ho gaya, halides ka ho gaya, oxides ka ho gaya, these are the most important part here okay whatever we have discussed property boiling point and all that is also important but this one is more important okay so first property of hydrides right down and that we are going to discuss here is bond angle, bond angle bohotar pucha examin, bond angle this is a bond angle here I'll write down the molecule first we have NH3, BH3, ASH3, SBH3 and BIH3 these are the compounds the exact bond angle if I write down it is for Ns3 it is 93.6 okay for ASH3 it is 91.8 for PH3 it is just a second for Ns3 it is maximum, Ns3 it is 107, 107 point something approximately 107 I'm assuming and this is 93.6 this is 91.3 and this one is 90 so as we go down the group you see bond angle decreases okay values you don't have to memorize let me tell you okay values you don't have to memorize trend you should know so as we go down the group bond angle of hydrides decreases okay and why this happens size is a factor, size is a factor we have size is a factor electronegativity is also a factor one thing also one general thing you write down here note I have done this last year in chemical bonding if you remember as the electronegativity of central atom increases as the electronegativity of central atom increases bond angle increases see the difference in these molecules are what Ns3, PS3, ASH3, SBH3, BIH3 the difference is the central atom correct Savito hydrides the only central atom is different okay and the central atom has different electronegativity also correct so what you have to keep in mind as the electronegativity of central atom increases bond angle increases this is the general thing you should know why this happens that also you can understand I'll write down here you see electronegativity is what electronegativity is tendency to attract shared pair of electron shared pair of electron lone pair kunei diktem okay tendency to attract shared pair of electron so nitrogen has three bond pair like this and one lone pair okay so since the electronegativity of nitrogen is maximum one more molecule I'll draw here pH3 okay the electronegativity of nitrogen is more than that of phosphorus so what happens this bond pair of electron is very close to this nitrogen atom here comparatively it is shifted towards the nitrogen atom yes or no in comparison to this phosphorus where the atom electrons will be somewhere here not as close as the electrons are there in the case of nitrogen okay now when these goes to this center then obviously these two electrons will have some repulsion they are coming closer right say they're coming they're going close to each other right that's why they feel more repulsion so the bond angle increases there to minimize the repulsion that's why the electronegativity of the central atom increases it drags the electron towards the side and hence these electrons experience more repulsion and to minimize this the bond angle increases that's why we say at the as the electronegativity of central atom increases bond angle also increase okay well please like I said you don't have to memorize trend you must know clear so what does VIH3 look like sorry what does VIH3 look like 90 degree bond angle VIH3 you said VIH3 yeah VIH3 is same no the bond angle is 90 degree correct so this what happens here VI is this okay and these bonds are almost at 90 degree to each other here we have one lone pair all these are nitrogen so H H and H it's formed a triangle here right and a lone pair here okay okay yeah then next the second property of hydrides are thermal stability the thermal stability of these hydrides freezes as we go down the group and why this happens any guess thermal stability means what thermal stability means stability towards heat okay so when you heat these molecules all these hydrides which one is most stable that's the question is is this hence stability degree okay third property reducing agent as we go down the group it's reducing character increases okay and why this happens okay okay reducing agent is what as we go down the group the it's reducing characteristics increases okay why reducing characteristics increases because it is related to thermal stability actually why this thermal stability reducing nature is what tendency to lose hydride and okay so right on the reducing nature reducing nature is it tendency to release hydrogen to release hydrogen so as we go down the group the thermal stability decreases the molecules becomes less stable then the atom hydrogen bond can break easily and hydrogen can go out that's why the reducing behavior increases as we go down the group so bi at three is the best reducing agent out of the five year okay the reducing behavior I'll lie down the order and it's three is minimum then ph3 P then as at three SB at three and then bi at three must remember this also basic character next one basic character as we go down the group the basic character decreases okay the reason of this is what basic character is nothing but a tendency to lose electron okay tendency to lose electron will be more when the electron density is high okay electron density means what suppose we have I'm supposed I'm comparing nitrogen and phosphorous okay basic character of this so nitrogen case art we have any three phosphorus we also have an history we have to actually find out the tendency for these molecules to lose this lone pair of electron which is present on the center lattice and that is a louis based behavior right nitrogen size is lesser than to that of phosphorus okay so electron density in case of nitrogen is more or less more so electron density is more here it means it can easily lose electron more electron density more tendency to lose that's why the basic behavior of an S3 is maximum among these hydrides okay so an S3 is the strongest louis space out of the five right now because of maximum electron density okay these are the four properties characteristics characteristics we have of these hydrides that you must remember now these elements also reacts with oxygen and forms oxides okay