[Music] hello and welcome to this gcsc chemistry explanation video about atoms elements and compounds in this video as well as looking at what each of those three things are we'll look at how we name compounds and also how we use formula atoms are the building blocks for everything around us from the air that we breathe to the screen that you're watching this from atoms are also mind-bogglingly small in one grain of table salt there could be as many as 1 million million million atoms so that's a one with 18 zeros after it the best way to visualize atoms is to think of them as the building blocks that are used to make up all the substances that we see in our lives just in the same way that a set of building blocks could be organized together to make a wall or separated into making two different colored Towers atoms can be constructed together in the same way to make a huge variety of different substances the biggest difference between the building blocks idea and atoms themselves is that atoms are normally represented as being circular and you might recognize this method of showing atoms from lower down your science studies and they might have been referred to Simply as particles but the idea of particles is actually a bit more complicated than you've already learned about because there are different types of particle and the smallest of these types of particle are called atoms and atoms are usually thought of as being the smallest amount of any particular substance that you can have and the word atom actually comes from the ancient Greek word atomos which means uncuttable or indivisible ible and this reflects the early philosophical idea that an atom was the smallest indivisible particle of matter which was a concept proposed by a Greek philosopher called democratus and this term was later adopted into scientific language and has become the basic unit of a chemical element now it is actually possible to break apart atoms and find even smaller things inside them called subatomic particles but once you start doing that the atom stops being a separate entity and it stops being the substance that it was actually taken from so it is definitely the case that an atom is the smallest amount of a substance that you can have even though it is possible to break it up into smaller pieces they no longer have the elemental properties that they had previously elements are the name for a type of substance that is only made up of one type of atom at and so this might be single atoms by themselves or it might be something larger made from lots of atoms but what all elements have in common is that each element is only made from one type of atom and you can see that from these pictures here each of these different substances have got atoms in them and in each case all of the atoms in each of those boxes are the same color and the same size which means I'm trying to show them as all being the same type of atom and as with before the atom is the smallest part of an element that can exist the atoms of each elements are represented by a chemical symbol sometimes also called a nuclear symbol for instance we've got Capital H for hydrogen and C for carbon n for nitrogen and O for oxy chemical symbols are crucial because they provide a universal language for scientists enabling clear communication about elements and compounds regardless of the speaker's native language they also simplify complex information for instance turning lengthy chemical names into concise symbols which is especially useful in chemical equations there are about 100 different elements but only 26 letters in the alphabet so there are far more elements than there are capital letters that we can use for the symbols and so that means that most elements have a chemical symbol that uses two letters and there's a rule that's really important for you to know here which is that the first letter of an element's chemical symbol is always a capital letter and the second letter is always in lowercase and so for some examples we've got Capital H little e for helium Capital C little a for calcium Capital C little L for chlorine and capital N little a for sodium and so you can see just from these examples that I've got three elements that all begin with the letter c but we've needed to use lowercase A and L to differentiate these three elements that all begin with the letter c you'll also notice that that last symbol for sodium does not look anything like the English spelling for sodium and that's because this word comes from Latin the word is natrium and quite a lot of elements have a symbol that seems unconnected to the English word and that's because it's taken from another language most commonly Latin the elements are all shown in the periodic table and you always get a periodic table in a chemistry exam and so it's really important that you understand how to use it most questions will focus on the first 20 elements in the periodic table although sometimes group one and group seven see a bit more use than others and we go down that group a bit more commonly we also sometimes use the first row of this middle block of the periodic table now you could be given a formula and be asked to name the elements in that formula or you could be asked to find the elements chemical symbol from the periodic table there are a variety of different things that you could be asked to do so it's important to familiarize yourself with the periodic table a lot of the everyday substances that we encounter are elements so for instance copper ion oxygen nitrogen carbon but you don't find all substances in the periodic table but the periodic table is sometimes referred to as the periodic table of elements so that means that if it isn't an element it won't be in the periodic table and it is in fact probably a compound compounds are substances that contain two or more different elements that have been chemically combined we sometimes refer to it as being bonded together and you can see that from these diagrams here I'm showing a variety of different compounds and each of the compounds has got more than one different colored atom being shown in its diagram and that's how we know it's not a Pure Element anymore because we've got different colored circles representing those different elements that have been chemically combined to make a compound you need to have some kind of chemical reaction between the elements that are going to bond together and this is what I'm showing in this bottom diagram on the left I've got the pure elements and then on the right we've got the compounds that they have been turned into the bonds that hold atoms together in a compound are very strong and that's something that influences the properties that different compounds can have another feature of this is that compounds can only be separated out into their component Elements by chemical reactions and so that means that we can't use physical methods of separation that we can do for some things that have been mixed together we have to use actual chemical reactions to pull apart the elements and to break the bonds that have been holding them together a simple application of this type of skill might be for you to just simply State whether a particular substance is an element or a compound and what you would need to do in this situation is to look at the substance and look at all of the atoms that are present in that substance and make a decision about whether they are all the same or whether there are different types of atom present and so for instance here all of the atoms are green all of the atoms in this substance are orange and all of the atoms in this one on the bottom left those are all blue and so even though we might have different arrangements and different numbers of atoms in each case these three are all elements because in each substance all of the atoms are identical whereas in the remaining three each of these substances are made of different types of atom and these atoms are shown as touching which means that they are bonded or chemically combined and you can see that the proportions present in each of these boxes is different so for instance here we've got one red for every two black atoms whereas this one on the bottom right there is one black atom and there are four orange atoms for each and in this top one there is one blue atom for every one orange atom and so you can see that we've got three compounds and we've got three elements when a compound is formed from the elements that are reacting together the elements always combine together in fixed proportions and this proportion is shown in the compounds formula and a formula uses the symbols for the atoms that we see in the periodic table and so we've got H2O which you'll probably recognize as the formula for water and that formula is telling us that there are two hydrogen atoms for every atom of oxygen and so when you have got one of a particular element we actually don't bother writing the number one in its formula we just assume that it's there but if ever you have got more than one atom of a particular element we do add that number and so in this second one we've got methane which has got the formula CH4 and there is no number after the C which means there's one atom of carbon and there's a four after the capital H which means there are four atoms of hydrogen in the next one we've got ammonia which has got one atom of nitrogen and three atoms of hydrogen on the right hand side in N you'll notice that we've got two capital letters one capital N with the a which means it's sodium and one Capital C with the lowercase L which means it's chlorine there aren't any numbers in this formula and that means that these compounds are combining in a 1: one ratio for magnesium chloride you can again see that there is no number after the mg which means there is one atom of magnesium but there are two atoms of chlorine for every one magnesium that is what the formula mg gcl2 means for the last one aluminium chloride you can see that there is one aluminium for every three atoms of chlorine and so these numbers that you see in the formula are the proportions or the ratios that these atoms combine together in in the compound a really important skill when working with compounds is to understand how compounds are named and it might be that you are given a compound's name and expected to be able to work out what elements are present in that compound from the name or you might be given a compound's formula and be expected to name it by working out the elements that are present and there are two really important rules which follow and are obeyed most of the time when we name compounds firstly if a compound contains two elements then its name is going to end in i and examples of this are sodium chloride magnesium oxide and you can see that as part of this rule for naming one part of the compound gets its full name as an element so the sodium and the magnesium in these examples and then the second element that's present gets a good part of its name but not quite all of it and the name for the element gets broken off partway through and it gets replaced with the letters i d e so magnesium oxide sodium chloride if there are three or more elements present in a compound the compound's name will end in eight so examples could be calcium carbonate or sodium nitrate and you can see in these examples that again one element gets its full name and another element get gets most of its name but then the ending gets chopped off again and it gets replaced with the eight and in both of these examples the third element is oxygen and its element name doesn't get any representation in the compound's name at all and so A good rule of thumb would be if a compound's name ends in eight the element that's present that you can't work out what it is from the name is highly likely to be oxygen there are some compounds that you will get more and more familiar with as you progress through the course and their names don't follow the rules as you would expect for instance water has got the chemical formula H2O and you wouldn't be able to work that out from the name water you just need to remember that water has the formula H2O another example is methane which is a greenhouse gas and it's a fuel that we use in bunson burners and that's got the formula CH4 and again you wouldn't be able to work out that there was one carbon and four hydrogens just from the name methane without some extra understanding as well and another example is amonia which has got the chemical formula NH3 this is a compound you will also encounter in the course and it's used to make things such as fertilizers it's got one nitrogen and three hydrogen atoms in another in convention that's often used in compounds made from just non-metals is if you've got one element and then you've got multiples of another element we might use the prefixes mono and d and tri so for instance we have carbon monoxide and carbon dioxide and carbon monoxide has got one carbon and one oxygen whereas the D in dioxide means we've got two oxygens for our one carbon we've also got sulfur dioxide and sulfur trioxide and the prefixes die and tri means that sulfur is bonded with two oxygens in the first compound but three oxygens in the second sometimes you might be required to work out the name of a compound from a formula so let's practice that now the first thing that we need to do is decide if there's going to be a name ending in i or eight and that's determined by how many elements there are present so in the first compound we've got zinc and we've got oxygen so that's two elements and then this means that the name is going to end in ID and so we're going to have the name of the compound as zinc oxy the end of the oxygen gets chopped away and replaced with I the second one also has two elements CA is calcium and BR is bromine remember you get the periodic table to check these in the exam this is going to end in i then and so the name bromine is going to have the last three letters chopped off and it's going to be replaced with I so this one will be calcium bromide the bottom two examples have both got three elements present we have magnesium and sulfur and oxygen in the first of those two so this is going to end in eight and so magnesium gets its full name it's very common that this is what happens for the metal sulfur loses part of its name ending the UR at the end and that gets replaced by eight so this would be magnesium sulfate and there' be no showing for the oxygen here its name doesn't get mentioned at all in the name for the compound and this happens again in our last one which has got lithium and nitrogen and oxygen present we get the lithium name in full the nitrogen has more of its word chopped off here and it becomes Nitro 8 because this is going to to be three elements present so this would be lithium nitrate sometimes you are expected to name compounds from the formula that are given to you as part of a symbol equation in this first one the first compound has got hydrogen combined with chlorine and so that's two elements and so that will be called hydrogen chloride here we've just got an element magnesium we can tell that because we've only got one Capital left are present in the products we've got magnesium bonded with chlorine and so this will be called magnesium chloride and the other product is the element hydrogen we can tell it's an element because there is only one capital letter in the second equation we've got hydrogen bonded with sulfur and also oxygen so that's three different elements and so this is going to end in eight and so hydrogen gets its full name here and so this is going to be hydrogen sulf 8 the oxygen isn't mentioned and sulfur loses the ending of its name the second reactant is cu which is copper bonded with oxygen so this will be copper oxide in the products we have copper bonded with sulfur and oxygen so that will be an8 name and so it will be copper sulfate copper sulfate and then the final product is one to Simply recognize H2O is the formula for water okay that's the end of this video I hope it was useful I'll see you again soon