because today we're going to talk about ions the term ion refers to any charged particle notice I did not say that we were talking about charged atoms or charged molecules an ion can be either a charged molecule or a charged atom we break ions down into two categories we break them down into cat hat ions and an ions cations ions are positively charged ions and annions are negatively charged ions everybody write down Hercules you can't spell caton without a positive sign right positive signs right there in the name so cations ions positively charged ions easy to remember plus cat people are positive people so cat ions positively charged particles and annions are negatively charged particles well how do atoms or any species develop a charge in order to develop a charge a species has to gain or lose electrons remember the number of protons define the identity of an atom so we can't change those we can however change the number of electrons an atom has for example let's take a look at sodium if we find sodium on our periodic chart it's element number 11 so it means that it has 11 protons and in the neutral atom it also has 11 electrons because in the neutral atom the number of protons equals the number of electrons sodium however likes to form a positive one cation it forms that positive charge not by gaining or losing protons but by losing an electron in order to gain a positive charge cions lose electrons so all your cations ions have a positive charge and they've all lost electrons they've lost a number of electrons equal to the charge so sodium here is plus one meaning it's lost one electron so it has 11 protons 10 electrons so it has a net charge of pos1 because it has one more proton than electron let's take a look at calcium calcium is atomic number 20 meaning it has 20 protons and in the neutral atom it has 20 electrons calcium likes to form a +2 ion in chemistry we write charges differently than you do in math class in math class you'd go plus two in chemistry we go 2 plus so the charge is going to follow the magnitude now we can't change our number of protons because if we changed our number of protons we would change the identity of the atom and we want to still have calcium here so we have to leave it at 20 protons to develop plus2 charge we will lose two electrons so our calcium plus2 ion would have 18 electrons or a net charge of 2+ let's have you try one my pal aluminum aluminum likes to develop ions with a +3 charge aluminum plus three how many protons electrons and electrons does aluminum plus three have pause me write down your answer real quickly all right first thing you had to do to answer this question was to pause me and answer it after you paused me the next thing you did was you went to the periodic table and you found that the atomic number of aluminum was 13 got that from your periodic table so you know that it has 13 protons whenever you have aluminum we have aluminum right so we know we have 13 protons so we have 13 positive charges we know that we want a net charge of positive3 so how many electrons do we have well 13 + x = 3 x must equal a -10 so we have 10 electrons another way to do it is if we have a plus3 charge that means we've lost three electrons no reason to panic when you discovered you lost electrons everybody write down panic we have a plus three charge meaning that our species must have lost three electrons and if it started with 13 and it lost three electrons it would have 10 electrons so our answer in case you were getting lost our answer is 13 protons and 10 electrons now I hate to be a negative person but I've got to I've got to talk about those annions as well so let's talk about our negatively charged ions here now our negatively charged annions are going to gain their charges the opposite way of our cations our cations lose electrons our annions actually gain electrons so our annions here gain electrons and they're going to gain one electron for each negative charge so for example let's start with an easy one let's start with one that we've referenced already in this class let's take a look at chlorine chlorine is number 17 on our periodic table atomic number of 17 meaning that anytime we have chlorine by definition we have 17 protons in the neutral atom that also means we have 17 electrons florine likes to form an annion with a -1 charge the only way we can develop charges is by gaining or losing electrons so for chlorine to become negatively charged chlorine it has to gain an electron so it goes from having 17 protons and 17 electrons to having 18 electrons to go with its 17 protons that gives it a net charge of -1 because it has one more electron than it does proton let's see let's try nitrogen nitrogen is atomic number seven meaning it has seven protons whenever we have seven protons we have nitrogen and in the neutral atom of nitrogen it also has seven electrons now nitrogen it's greedy when it forms an annion it likes to actually gain three electrons to develop ag -3 charge it's nitrogen so it still has seven protons but it's gained three electrons so that it has 10 electrons that gives it three more electrons than it does protons so it has a net charge of -3 also notice once again we write the magnitude first followed by the sign convention and I'm not sure if you can tell every time I'm writing these charges I'm writing them as a superscript and I'm writing them on the right hand side let's have you try an example here all right i've got an annion of oxygen there with a two negative charge how many electrons and protons pause me and get the answer i'm sure you paused me i didn't mean to cause you any pain if you didn't pause me everybody write down pain we have to include Hades psychics here if we're talking the Hercules movie all right so first thing you did you went to your periodic table you located oxygen and you found that oxygen is atomic number eight so you have eight protons in the neutral atom that also means that you'd have eight electrons since I have a two negative charge that means I gained two electrons somewhere so I have eight protons and I have 10 electrons because by having two more electrons than I do protons I get a -2 charge chemistry is easy life is hard particularly when it comes to ions i hope you found this a exciting experience keep