 All right, since y'all seem to struggle with the atomic structure the ions I'm going to put a video up This is the Bell work from Friday and explain how to do this atomic structure again so that you can watch it anytime you need it Well, we're doing the atomic structure for anything The nucleus part of it all stays the same The protons are always the atomic number and the neutrons are always the mass number minus the atomic number It doesn't matter if it's a standard average atom an ion or an isotope Those are always the same protons or atomic number neutrons are mass minus atomic number in the ions It's going to be the electron stuff that's different and the way I'm going to show you how to do it is based on noble gases The idea being that when a substance forms an ion its ultimate goal is to look like a noble gas to have the same total number of Electrons as a noble gas have the same number of energy levels valence electrons as a noble gas I Put charge on here because you can use charge to find the total number of electrons and figure out what noble gas that is that it looks like When you're dealing with an ion the total number of electrons is the atomic number minus that charge So that charge for strong name is plus two We can use that charge when we get the total electrons to figure out what the noble gas is that it resembles Protons again or atomic number, so we just find strontium on the periodic table. It's right there Strontium is atomic number 38, so it has 38 protons For the neutrons it's going to be the mass number minus the atomic number now. This is not an isotope. There's no numbers over here on the left So you look to the periodic table to get its mass number the mass of strontium is eighty seven point six two Which rounds to 88? So to find the number of neutrons here is going to be the mass number 88 minus the atomic number 38 Which gives us a total of 50 Again that mass will come from the periodic table Eighty seven point six two the six rounds that seven up to an eight, so that is 88 minus the atomic number 38 That's where 50 comes from Again for total electrons we can use this charge Total electrons is the atomic number minus the charge atomic numbers 38 minus a positive two Gives us 36 And again this has to equal one of our noble gases 36 is krypton, so when this is done It'll resemble the element krypton Another way to figure that out is to work backwards from your metal Metals will always resemble the noble gas that comes before it on the periodic table So to figure out what noble gas comes before it you work from your metal and you count backwards, so 38 37 36 it'll resemble krypton, and we'll have the same number of total electrons as krypton Energy levels are period number, but it's not period number of strontium. It's period number of that noble gas of krypton So this is period one two Three four five six and seven Krypton is in period four So we know it has four energy levels And for valence electrons, it's the same number of valence electrons as this noble gas as krypton Krypton Is in group 18 Drop the one Krypton has eight valence electrons Let's skip aluminum. I'm gonna go on down to bromine and do a negative ion. This one has a charge of negative one so Protons are still atomic number always have been always will be doesn't matter what type of atom it is There's bromine this atomic number is 35 Neutrons are mass minus atomic number always have been always will be doesn't ever change The mass here for the bromine is seventy nine point nine zero so that rounds to eighty Minus thirty five Eighty minus thirty five It's forty five And moving on to the total number of electrons again, we can use this charge Comic number minus charge the atomic number the bromine is right there 35 Minus negative one 35 minus negative one is the same as adding one So we don't put 36 Again, it has to be equal to one of these noble gases And 36 is Krypton again just like up here The energy levels and valence electrons are based on Krypton Krypton is in period four So it has four energy levels Krypton isn't group 18 drop the one And it has eight valence electrons These are the same because they resemble the same noble gas