Isotopes and Elements Practice Problems

Here in this video we will see how to discover and solve all these characteristics or properties of an atom. If you want to follow the process on your own, you'll need a periodic table so you can look up atoms as we go. Come on, given just these two pieces of information, we have to figure out everything else. This is like a puzzle or a logic game, like a pseudo ku. We'll go step by step so you can see how to do this. Start here, the chemical symbol is na, so we'll look up na on the periodic table and find out that's a symbol for sodium, so now for the isotope name, we know it's going to be sodium, that's just the In the first part, the name of the isotope tells us what element it is and then it has a mass number, after the number of protons plus the number of neutrons, the mass number has already been given to us, so we know that the name of the isotope will be sodium na and then 22 of the mass number now that we know that na is sodium we can fill in the atomic number and the number of protons because when we look this up on the periodic table and a sodium has 11 at the top, this number up here is the number atomic number of protons then 11 for the atomic number 11 for the number of protons now for the number of neutrons the mass number here is the number of protons plus the number of neutrons so if we want to find just one number of neutrons we can let's do protons and neutrons: protons equal 11 neutrons, that's how many neutrons we have now, finally for electrons, let's look at our Sigma, let's look at our symbol here, okay, it's written na 1 plus because there's only one plus sign there, so is 1 more, this is the net charge, the net charge tells us how the protons and electrons balance, so if it is 1 more, it means there is one more proton than one electron, so 11 protons, which means we have 10 electrons, we're going to give this atom a 1 more charge, so based on just these two pieces of information we can figure out everything else here.

We know protons, neutrons and electrons. Let's start with protons 44. Here we can look up the periodic table and find out which element has an atomic number. of 44, okay, you have 44 your ruthenium, so I can put it here. There's the isotope name ruthenium, but I'll still have to go back and deal with a mass number that we then put here in the isotope name, atomic number. I can take care of that right away, it's 44, the number of protons you don't even have to look it up on the periodic table to complete this, let's move on to the mass number now, the mass number is protons plus neutrons, so I'll do 44.

Plus 56 that will give me a total of one hundred for the mass number. Now I know the mass number, so I can put it here at the end of the isotope name ruthenium 100 and I'm ready with this, the only thing I have left. now is the chemical symbol with a net charge let's go back to the periodic table here is to find out what the chemical symbol is is a chemical symbol here is ru and now for the net charge we will put two protons and electrons here, so there are 44 protons and 40 electrons, which means there are four more protons than electrons, so there will be a net charge of 4 + ru 4 and you will also end up with this as the chemical symbol with a net charge of iodine-131. and it has a negative charge 1 - let's start by looking it up in the periodic table we find iodine, big capital letter I, it has an atomic number of 53, so 53 here 53 is also the number of pro the number here that comes in the second part of the name of the isotope is the mass number, the number of protons and neutrons together, so based on this information, the mass number I can find the number of neutrons, so protons plus neutrons - protons - 53 will give me 78, that's the number of neutrons and finally the electrons up here in the chemical symbol we get the net charge has a 1 - charge there is 1 - there that means we have to have one more electron than protons so 43 protons sorry, 53 protons I can count, I can count 53 protons, 54 electrons and finally mg 2 more with 13 neutrons.

I'll look this up on the periodic table if you didn't already know that this mg is magnesium, so I'll write that here magnesium you look up magnesium on the periodic table. In the table you can get the atomic number up here, so it's 12, the number of protons is also 12 because they are the same thing and now that I know the protons and the neutrons, I can get the mass number. 12 protons plus 13 neutrons equals 25, there is my mass number and now I can use the mass number to finish the name of the isotope up here it will be magnesium 25 finally I need to complete my electrons from this symbol up here I can say that I have a charge of two more in this ion two more means that there are two more protons than electrons, so if there are 12 protons I will end up with 10 electrons, this is how you can solve

problems

like this, you have to go step by step and find out what you can do. do it at each step and then you'll see the information as if they were clicks together, like you were doing a puzzle or a Sudoku or something.