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Atomic Structure: Atomic Number, Mass Number and Net Charge

Added Sep 22, 2015 •

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here's a diagram of an atom it's not perfectly accurate but for what we need right now it's going to do just fine so we in this lesson we're going to look at care rustics that we can use to describe atoms like this one It'll ask you to describe a person chances are you use characteristics colorize what their height is and so forth just like that their characteristics we can use to describe apps the first of these characteristics and maybe the most important is the atomic number atomic number is often abbreviated by a capital letter Z and what the atomic number is is it's the number of protons in the nucleus of atom in my diagram here I'm using these red circles to represent protons so I have one two three protons in this atom so the atomic number is going to be three for this atom here atomic work is particularly important because the number of protons in an atom tell us what kind of an atom is and by that I mean is it a carbon atom is an turn arm is it a sodium atom where can talk more about that in the video on Isotopes so you don't have to worry about it for right now  the next important characteristic that we can use when describing atoms is the mass number of an abbreviated by uppercase a year mass number is the number of protons what's the number of neutrons in the nucleus of an atom people always get confused by mass number here's why atomic number is number of protons so everybody always wants to be the number of neutrons but it's not it's a number of protons and neutrons there's not really a name for the number of neutrons just the number of neutrons an atom we just don't use it that often so when away from mass number one account follow this together 1 2 3 4 5 6 7 the mass number of our Adam here is going to be 7 no finally four characteristic we're going to talk about here is probably the most complex and that's called net charge  I don't have a good way to define that charge a man a good definition to say here is it how protons and electrons balance each other out let's talk a little bit more about this charge is about how protons and electrons balance each other out so protons as you know have a positive charge and electrons have a negative charge so that means that if we have the same number of protons and electrons in an atom like I have right here three protons and three electrons not trying the neutrons here because we're not worried about here we have the same number of protons and electrons they're going to balance each other out 3 - is going to balance out the three positive so we're going to end up with an atom that has a net charge of zero because he's who sings Bounce out and we can call this atom neutral which means it has no net charge now what would happen in an atom where we have four protons and three electrons we don't have the same number of electrons and protons anymore so they can't totally balance instead we have more protons than electrons so that we're going to have a net charge that's positive because there's going to be some of this positive charge of proton can't be balanced out by the electrons in this case we have one more proton than electron so this is going to give us a net charge of Plus one since our atom has a net charge we give it a special name we call it an ion and ion is any atom that has a net charge new pause what you call it if you don't have a charge is what you call it if you have any charge okay this is where we have one more proton than electron what about this what do we have 5 protons and three electrons in this case the charges don't balance out either but now I have two more protons than electrons two more protons that aren't getting balanced out by these electrons so that means I'm going to have a net charge of 2 + for these two protons and again is this going to be an ion because it's got to charge  no the opposite can happen as well here is an example where an atom has four electrons reproach these three protons can only balance out three of the electrons to have one more electron it's not getting balance doubt that means this total charge is going to be minus one that's a charge of this one more electron that I have in the if I had a case in which I had five electrons I should have said we call this and I on because I have a charge just like this negative charge positive charge it doesn't matter if it's got a charge we call it 9 okay so anyway we have a place where we have five electrons and three protons now there are two more electrons and protons so I have two negative charges that are getting balanced out by the proton which means that I have a net charge of -2 and this also is an ion so that's how you can figure out charge so what's the charge for this what we have one two three four electrons 1 2 3 protons since they're different numbers the protons and electrons are getting a balancing each other we have one more electron and proton is that means that we have a negative charge and since there is one more electron and proton Adam here is going to have a net charge of -1  so now that we've talked about these three characteristics you can use to describe an atom what's look the practice Problem video so you can go over this in a little bit more depth and try a bunch of it

Uploaded by Laura Houston.

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Atomic Structure: Atomic Number, Mass Number and Net Charge

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