hello lovelies in this video we're going to be looking at period three for your a Lev chemistry everything you need to know about this period and how it reacts with other things now if you want to take everything you've learned and see if you can put it into practice and exam style situation then over my website there is a big long course to help you remember all the different bits that you need to know period three elements sit across here starting with sodium and magnesium moving across to aluminium silicon phosphorus sulfur chlorine and argon they will all have the same number of shells but as we move across the period we will get a different number of electrons in the outer shell as the number of electrons increase we will see a change in the properties and that is what we're going to be looking at sodium magnesium and aluminium are metals and the rest are non-metals if we look at the electronic configuration we can start to get information on the properties sodium and magnesium are in the S block that electrons will end with this s shell as we move across the group we can start to see the P being filled up here until we get to argon which has a full shell sodium and magnesium are s block elements whereas the rest of them are over in the P block as we move across we can see a change in the structure and the bonding of period 3 elements sodium magnesium and aluminium will show metallic bonding and the properties that come along with that silicon will make giant Co valent structures phosphorus sulfur and chlorine will make simple calent structures and argon is monoatomic metallic bonding and giant calent structures will have high melting and boiling points whereas the rest of them will have low melting and boiling points due to the differences in the type of bonds Vander Val bonds bandal forces are much weaker than metallic bonding the electrostatic forces that we see in that we can see it on the graph here with the metals moving up to aluminium and then moving down to the ones that show simple Cove valent or monoatomic bonding when we look at atomic radius and ionization energy in Period 3 we see some really interesting things the atomic radius decreases across period 3 as the protons and thus the positive charge increases but the number of shells stays the same there is an increase in the electrostatic attraction of the nucleus on the electrons pulling them in and decreasing the atomic radius if we look at the ionization energy and down here I've just written the groups to remind you the electrons in the outer shells and when I'm quickly going to draw on all the electrons the three electrons in the third shell so for sodium we just have the one electron the 3 S1 all on its own in its orbital magnesium has a PIR in the 3 S2 whereas aluminium again just has the one on its own a bit higher up in the 3p silicon has them filling singly sood this phosphorus before we start to fill doubly with sulfur where we have a pair singly filling the rest of them chlorine will have two pairs where as argon is going to be fully paired up so what we can see is a slight drop between groups two and three and another drop between groups five and six as pairing starts because remember first ionization energy is a measure how hard it is to remove the first outermost electron and anything that makes it harder moving from s to P or pairing starting will decrease it compared to the previous one we're going to look at the reactions of period 3 elements with water limited to sodium and magnesium since they are the only ones that react sodium will react to give sodium hydroxide and hydrogen gas sodium is an alkaline metal so you may be hopefully familiar with this practical which we used to Value lower down in the Skool it is a very EXO mic reaction that will take place so you might see flames you might see fizzing happening sodium hydroxide is going to be very very alkaline so with the green indicator here you see the change in color to a blue purple color giving us indication that the pH is 13 to 14 it will give us a very Alkali solution we will also see fizzing and moving around as hydrogen gas is evolved magnesium will react with water to give us magnesium hydroxide and hydrogen gas this is a much less impressive reaction it will react slowly with cold water but quickly with [Music] steam it will still be alkaline but less alkaly solution will be produced roughly ph10 as magnesium hydroxide is less soluble in water here we have the reactions of period 3 elements with oxygen looking at sodium to sulfur since argon is inert and monoatomic it doesn't really react much sodium orct gives sodium oxide this is an ionic compound here and we're going to need hot sodium in oxygen magnesium will react to give magnesium oxide this is another one with ionic bonding and again it needs to be burning really really hot for reaction to take place aluminium metal is generally always covered with a thin layer of aluminium oxide and to get it to react you need to rub it and it will react again aluminium oxide is ionic with Co valent characteristics silicon reacting with oxygen will give us silicon dioxide which has giant calent structure phosphorus and oxygen will give us p410 or p203 in limited oxygen sulfur reactant will give us sulfur dioxide and some sulfur trioxide and these are all Co valent compounds the ionic compounds will have high melting and boiling points whereas the other ones will have lower ones this is the reaction of three oxides with water sodium oxide will react to give us sodium hydroxide this is a strongly alkaline solution with a pH of 13 or 14 this reaction is very exothermic magnesium oxide will react with water to give us magnesium hydroxide is alkaline but slightly less so at ph10 as the latice is stronger aluminum oxide is insoluble in water so there is no reaction it has very strong ionic lattice silicon oxide is also insoluble in water these will give a pH of seven the pH of water P4 h10 will react with water to give us phosphoric a acid this is a very exothermic reaction and it is a strong acid it has a pH of 1 to2 sulfur dioxide will react to give a sulfurous acid it will have a pH of 2 to three and this is a weak acid sulfur trioxide will react to give us sulfuric acid this has a lower pH at 0 to one and this is a strong acid remember the strength of an acid is different to its concentration for the structure of phosphoric acid we have phosphorus in the middle double bonded to an oxygen single bonded to another oxygen then to a hydrogen and this happens two more times for the ion we lose one of the hydrogens and it is replaced with a negative charge for sulfurous acid we have our sulfur in the middle double 1 Z2 and oxygen and two lots of o on there and again for the ion one of those will lose the hydrogen and get a negative charge very similar for sulfuric acid except we have two double bonded oxygens on there and one of those will leave ose the hydrogen period 3 oxides can also react with acids and bases basic oxides will react with acids to produce salt and water react with hydrochloric acid to give us sodium chloride and water this follows the very familiar reaction of base plus acid equals salt and water and works for both sodium oxide and magnesium oxide with whichever acid you would like to react it with here magnesium oxide is reacting with sulfuric acid to produce magnesium sulfate and water anic oxides can act as both acids and bases aluminium oxide can react with hydrochloric acid and is acting as a base to give us aluminium chloride and water it can also act as an acid with aluminium oxide reacting with sodium hydroxide the rest of period 3 form acidic oxides silicon oxide will react with very concentrated sodium hydroxide and only very concentrated as it is insoluble in a weak base or in water the rest will act as acids as follows sulfur dioxide when released into the environment is a polluting gas that can cause acid rain this reaction is one way of removing polluting gases from Industrial Waste ouch this is why in some videos I have had explain scratches [Music]