hey guys welcome to igcc study Budd where you can revise chemistry topics from the Cambridge igcc syllabus if you are enjoying our video so far please don't forget to hit the like button and subscribe to our channel in this video you are going to learn part two of topic 8 the periodic table first let's dive into group one the group one metals are also known as alkaline metals lithium sodium and pottassium are examples of alkal metals they are relatively soft Metals you can cut them with a knife as you go down the group you may notice some Trends in alkali metals related to their physical proper properties such as their melting points and densities melting points decrease as you move down the group so as you go down the group the lower the temperature it takes to change the element from a solid to a liquid density is how heavy something is for its size density increases as you move down the group group group one metals react similarly with water here are the observations of the reactions of the first three elements in group one with water lithium reacts slowly with water produces fizzing and moves on the surface sodium reacts more vigorously than lithium with more fizzing and faster movement pottassium reacts even more vigorous ly burns with a lilac flame and moves rapidly based on the above observations we may identify a trend occurring as you go down the group that reactivity of group one Metals increases as you move down the group now given this information about the first three elements of the group we may predict that the lower group one Metals will react even more strongly the predictions are rubidium will react violently with Sparks the reaction will be more vigorous compared to potassium cium will cause a violent explosion and francium is too reactive to predict even when reacting these elements with chlorine or oxygen the same Trend in reactivity is observed reactivity increases as you go down group one in each reaction the other properties of group one elements may also be predicted by observing Trends in known elements for example if we observe that the density increases in the first three elements we can predict that subsequent elements will have even higher Den densities similarly if we see that the melting point decreases in the first three elements we can expect it to decrease further in the elements further down the group now we will move on to group seven properties the elements in group seven are also known as hens chlorine bromine and iodine are examples of halogens they are diatomic non-metals example cl2 br2 and I2 diatomic means a molecule made up of two atoms for example chlorine is diatomic because it has two chlorine atoms bonded together all halogens have seven electrons in their outer shell they gain one outer electron to get a full outer shell and become halide ions with a minus one charge at room temperature and pressure these are the appearances of the halogens chlorine is a pale yellow green gas bromine is a red brown liquid iodine is a gray black solid please keep in mind halogens have distinct colors at room temperature but their colors change in aquous solution or as gases let's look at the trends down the group the density increases as you go down group seven which is reflected in the state of each element Chlorine is a gas bromine is a liquid and iodine is a solid the reactive of group s non-metals decreases as you go down the group this trend is the opposite to group one's reactivity Trend in group one elements as you go down the group the positive nucleus attracts the outer electron less strongly this makes it easier for the element to lose its single outer electron so reactivity increases in contrast cast for group seven elements at the top of the group the positive nucleus attracts electrons more strongly making it easier to gain an electron so reactivity is higher up the group as you go down the group this attraction weakens making it harder to gain an electron so reactivity decreases we should be able to predict the properties of other El elements in group seven given information about the elements so now that we know the appearance of chlorine bromine and iodine at room temperature we can predict that the next element down the group atine will have a darker color and be in a solid state the melting and boiling points increase down the group so atine will have a higher melting point than iodine density increases down the group so atine will be denser and heavier than iodine reactivity decreases down the group so atine is likely less reactive than iodine a displacement reaction is when a more reactive element takes the place of a less reactive element in a compound in displacement reactions involving halogens a more reactive hogen will displace a less reactive hogen from its compound so a more reactive hogen displaces a less reactive hallogen from its halide salt the less reactive hogen is displaced by the more reactive hallogen this results in a new halide salt being formed with the more reactive hallogen let's look at some examples to get a clearer understanding in the case of chlorine reacting with a bromide here's the reaction chlorine is more reactive than bromine it displaces bromine from sodium bromide forming sodium chloride and bromine gas since bromine is the less reactive hogen it gets displaced by chlorine a new halide salt sodium chloride is formed with the more reactive hogen chlorine for chlorine and iodide here's the reaction chlorine is more reactive than iodine so chlorine displaces iodine from sodium iodide producing sodium chloride and iodine gas in the case of bromine and iodide bromine is more reactive than iodine so bromine displaces iodine from sodium iodide forming sodium bromide and iodine gas so the general Trend in hallogen reactivity is that as you move down the group reactivity decreases Florine is the most reactive followed by chlorine bromine and then iodine in any reaction a hallogen higher in the reactivity series will displace one lower in the series from its haly salt next let's dive into transition elements transition elements are metals found in the middle of the periodic table iron nickel and copper are examples of transition metals transition elements are metals that have high densities have high melting points form colored compounds and often act as catalysts as elements and in compounds transition elements have ions with variable oxidation numbers this means that they can lose different numbers of electrons resulting in ions with different charges example ion commonly forms two oxidation States Ion 2 where it loses two electrons and ion 3 where it loses three electrons finally let's shift our Focus to noble gases noble gases are the elements in group 8 or group zero of the periodic table helium neon and argon are examples of noble gases group eight noble gases are unreactive their atoms have a highly stable electron configuration in their outer shells so they do not need to gain lose or share electrons this stability is why they don't readily react with other elements for example helium has two electrons filling its only shell so it's stable neon has two electrons in the first shell and eight in the second making it stable as well and so on noble gases are monoatomic gases meaning they exist as single atoms and are not bonded to each other or other elements because their outer shells are full they have little tendency to form bonds that concludes topic 8 the periodic table are you enjoying our videos are they helping you here's a way you can show your appreciation and support our continued efforts you may use YouTube super thanks to send us thanks hope this video helped you please share your thoughts and suggestions in the comment section thank you for watching and please don't forget to subscribe to igcs study body for more revision videos bye-bye