hello everyone welcome back to straight cam now we're going to learn how to write isotopic notation but before we're going to do that there are a few definitions that we need to know the first one we need to know that matter consists of atoms but the question is what is matter so the general definition for matter is matter is consists of i'm going to rub that off first okay so that is the definition of matter matter is anything that takes up or space and they have mass so if you occupy some space if you have mass and therefore you matter okay so what is an accent then okay so that is the question what is an acid so if i'm gonna reveal that to you like this so basically atom is from this definition atom is the basic unit of matter that consists of a central nucleus and that nucleus is surrounded by a cloud of negatively charged electrons so atoms if you go further into the definitions and the knowledge of atoms it has for your level three subatomic particles of course we have a lot more subatomic particles but for matriculation level we're going to focus on three sub atomic particles the word subatomic particles over here refers to the thing the particle that is inside the accent so you can imagine that we are talking about something that is super super tiny okay so the first super tiny stuff that we're gonna be talking about is electron okay atom they have electrons and that electrons will always going to be negatively charged and there will be surrounding the nucleus and inside the nucleus we have protons and this one is write that properly for you protons and this is positively charged and of course in the nucleus you also have neutrons okay so for this over here you will find that in the nucleus okay so i'm going to show you i'm going to show you the diagram now just like this okay so this is a a very good representation of what atoms should be looking like okay so you have your electrons surrounding your nucleus and then inside your nucleus you have your neutrons the one in yellow and you have your protons the one in red okay so neutrons and protons will be the building block if i must say for the nucleus and then they will be surrounded by electrons the most important thing over here that you need to know is the mass number the mass of the atom is determined by the number of neutrons and the number of protons okay so when you add those two numbers together you will have the mass number for a specific atom now let's move on to the next one okay so how do we write as a topic notation the one that you're looking at now this is just the general way of writing it okay so you're gonna have the symbol of the atom written right here and then on top you're gonna have the mass number remember mass number just now refers to proton plus neutron or sometimes mass number can also be called as the nucleon number and then at the bottom over here you can have the proton number or the atomic number z okay a is the symbol for mass number z refers to the proton number now so if you look at this explanation a is the total number of protons and neutrons in the atomic nucleus just like what i have shown to you just now in the diagram right here you have your proton neutrons inside your nucleus you add those things together you will have your mass number okay so we go back to here z is the number okay z is the number of protons found in the nucleus okay sad is a proton found in the nucleus so when you look at the isotope itself what does it mean by isosceles so that is the most important thing that you need to be thinking of so isotopes the definitions that we have is this you can use this this is one of the most common definition for isos so isotopes are two or more atoms of the same element so you need to have two or more atoms and you need to mention the same elements and they have the same number of protons in the nucleus but different number of neutrons so that is the definition of isotopes okay so when we look at one examples let's say we take hydrogen okay so this hydrogen the symbol will be h of course okay and then a equals to 1 the mass number is equals to 1 and the proton number equals to one as well so what is the asset subject notation so how are you going to write that so this is how you're going to erase it it's very simple so what you have over here the symbol x is h you're going to write it there very specifically for hydrogen and you have the value of a which is one i'm going to put one over here just like what you have a right there and then z one right here okay so let's have a look at more examples for hydrogen so this is the same hydrogen that we have just now so z is the proton number one and you have one on top so a the nuclear number is one or the mass number is one therefore neutrons in this hydrogen um isotopes also known as protein is zero it does not have a neutron okay so let's have a look at the other two look at the other two you have deuterium okay now it's slightly different now you have two so the nuclear number will be two so two minus one you'll get one neutron so inside deuterium it has one proton okay two um sorry you have one proton and one neutron okay two over here refers to the nucleon number and the next one is this when you have tritium tritium instead of two you have three so three the nuclear number is three proton number is one and the neutron is just simply taking three minus one you'll get two okay so the number of proton is one the number of neutrons is two so how many electrons in here remember if you do not have a charge like what you have in here you do not have a charge proton number okay is the same as the electron number for neutral species okay so this i'm gonna write that properly for you species okay so the the word species over here refers to your tritium deuterium and protein now proton number will be the same as the electron number if you have the statement since they are neutral species the electrons for all of them will be one because they have one proton number now same goes to carbon you have 12 okay 12 nucleon number six proton number 12 minus six we have six neutrons and same goes to carbon 13 and carbon 14. now we're going to try and do some questions here okay so you have four species okay given to you you have four species and you need to give the number of protons neutrons and electrons and you need to state what is the charge obviously for hg or mercury and copper the charge is zero yes so over here the charge is zero because they do not have charge if you look there you don't have charge like these two they have charges okay so when they have charges that one will be to negative this one is three plus charge okay for the charge that is okay so what about the proton number okay what is the proton number over here for mercury is it 200 or is it 80 cost it is going to be 80 and then the neutron is 120 how do you get that how do you get the number of new term one two zero you're simply going to take 200 minus 80. okay remember what we have talked about before this so this number is when you have 200 minus ac to get the number of neutrons remember this is not nuclear number this is neutron number so what about the number of electrons we have zero charge you have 80 protons uncharged species thus you have the same number of electrons for copper you have 29 29 right over here and then 63 minus 29 okay 63 minus 29 you'll get the number of neutron 34 and the number of electrons is the same as the number of protons okay electrons and protons will have the same number because you are uncharged species and for oxygen you have eights 17 minus eight you have nine for the electron since you have charge two minus means you have two additional electrons you have 10 now okay 10 electrons they cannot be the same okay you have eights over here you cannot have a to b here because you have charge two minus two minus means you have two additional electrons so eight plus two you have ten i hope that is clear okay now for couples you have 27 proton number 27 and you take 59 minus 27 you'll get 32. this time instead of adding electrons you are going to be taking away electrons if cobalt is uncharged the number of electrons will be the same as the number of proton isn't it you can have 27 but this time the species has lost three electrons so 27 minus three you have 24. that's how you're gonna look at the piece of information from the isotopic symbol