 All right, let's review what you should have learned in physical science all the stuff that you're expected to still be able to do in Chemistry I know I said I was gonna make a video on this, but hey, I like to hear myself talk and I know you do too. So Here we go you gotta be able to describe the basic atomic structure of elements and Ions and isotopes using a periodic table So let's get to it Start with a typical kind of normal atom of an element. Nothing special. No isotope. No ion sodium To find the number of protons for any element you have to look up its atomic number So we get out our trusty periodic table We find sodium That number in the top corner that is 11 is The atomic number the atomic number tells us the number of protons to find the neutrons We'll do the mass minus the atomic number. So again, we go back to the periodic table. There's the mass of sodium 22.99 we're gonna round that to 23 and Then subtract the atomic number from it So 23 minus 11 There are 12 neutrons and a sodium atom now for electrons This is a neutral atom. We know it's neutral atom because there's no charge up here in the upper right hand corner And in a neutral atom the number of protons and electrons Have to be the same on the energy levels You know we go back to our trusty periodic table Now what we have to do is see what period sodium's in Period numbers over here on the left. This is period three And finally valence electrons valence electrons based on group number So we go back to the periodic table. We find out what group sodium's in so do you think group number one? Group number one has one valence electron group one has one group two has two Almost all the elements in three through 12 have two Group 13 has three 14 has four 15 has five 16 has six 17 has seven and 18 has eight Well, that's your typical atom just a symbol no numbers attached to it when you start attaching numbers to it Then you've got either ions or isotopes if you see these little positive and negative numbers Then you know what you're dealing with there is an ion This says F negative one that is an ion and what that means is the number of electrons have changed To find the protons is still the atomic number So we go to our periodic table find flooring Atomic number is nine To find the neutrons for an ion. It's still mass minus atomic number So again, we go to the periodic table. There's the mass of flooring. It's 19 Minus nine there are 10 neutrons in a flooring ion Again when we have an ion what changes is our electrons To find the electrons in an ion. It's the atomic number minus the charge atomic numbers nine The charge is right there Negative one so it's nine minus negative one That'll be ten now. I'm gonna let you in a little hint didn't mention this in class For most ions when you find the number of electrons, it's gonna have to equal one of these noble gases The noble gases are naturally stable All these ions formed to make atoms stable So when we're done the electrons have to be the same as a noble gas either two ten 1836 54 I think that says 86 This one's 10 so it does equal one of our noble gases. It's the same as neon's That's a little hint so you can check yourself when you do the electrons in an ion As far as energy levels are concerned two ways to think about it negative ions They don't lose energy levels or what you can do is you can look it up with the new number of electrons, which is 10 Look it up based on neon Again, it wouldn't change we have to go all the way over to the side of the table fluorine is in period two So it still has two energy levels again negative ions don't lose energy levels when they form So we can just look up fluorine and go with that Or we can look at that new number of electrons and see where it is in the periodic table That's neon's number of electrons and base everything we say on that As far as valence electrons are concerned The whole reason these things form is to become stable. So most of the time you're gonna end up with eight valence electrons in your I am there are a few exceptions though hydrogen lithium and beryllium are exceptions and again You can use that same little shortcut. It's 10 now in terms of the number of electrons So it's gonna have the same number of valence electrons as neon Which would be eight? We'll get more into that when we do our electron configurations and we get to ionic bonding Next one calcium with a plus-two charge Calcium I am again the protons are always going to be equal to the atomic number the atomic number of calcium is 20 The neutrons will be equal to the mass minus the atomic number the mass is 40 Minus 20 20 neutrons there This is an ion again, we see that plus-two charge there and for an ion what we have to do is the atomic number minus the charge Minus positive two in this case because that's what it's telling you right there That's 18 and again the self-check It's got to be equal to one of these noble gases. It's equal to argons 618 Far as energy levels are concerned the period number for calcium is four but in a positive ion We're gonna lose one energy level So it's gonna be three again. The other way you can do that is by looking at that new number of electrons It's got 18 electrons. It's like argon now and argon is in period three valence electrons again in almost all the ions except for hydrogen lithium and brillium it's gonna be eight and Again, you can just ask yourself well with this new number of electrons with 18 electrons How many valence electrons would I have and the answer is eight? Last one here. This is an isotope. We got a 14 and a 6 there You got those two numbers on the left-hand side that tells you it's an isotope this number on top is the mass The number on the bottom is the atomic number Prozons are still equal to the atomic number We can look it up on the periodic table or we can just get it from the isotope symbol in six The neutrons are still mass minus atomic number, but we're not looking at the periodic table. We're using that mass right there 14 minus 6 is 8 I can don't use the periodic table when you have an isotope It gives you a mass you have to use that mass when you find the number of neutrons There is no charge over here. So it is a neutral atom Protons and electrons are the same in a neutral atom We need the period number for the energy levels. There's carbon second row down two energy levels and For the valence electrons is based on group number. This is in group 14. We have to drop the one group 14 has four I can make sure we drop the ones in The teens when we're up in 13 14 15 16 17 and 18 group one has one Group two has two groups three through twelve the B groups. They have two for the most part Group 13 is three 14 is four 15 is five 16 has six 17 has seven and 18 has Next thing we gotta do here is draw a Bohr model for calcium We've got most the information we need for calcium here, but we're going to use the average atom this time The protons are still the atomic number. That is 20 For the neutrons it's still 40 minus 20 and again, we're using the neutral atom this time So instead of this one here, we're going to make the protons and the electrons equal for the energy levels because it's a neutral item We're going to use the actual period number, which is four And for the valence electrons, we're going to look at the group. It's in Calcium Isn't group two So it has two valence electrons So you we're not doing this calcium up here. We're not doing the plus two. We're doing the neutral atom Because it's a neutral atom the protons and electrons will be the same 20 piece The energy level will be equal to the period number this time and calcium is in period four And then the period numbers are on the side over here. Calcium is in period four And the valence electrons will be based on the group number There's calcium group two two valence electrons Start with the nucleus right in the protons and neutrons 20 and 20 We're not drawing the little dots or circles to represent the protons and neutrons because you don't want to draw them I don't want to count them Drawing our four rings for our four energy levels one two three Four not being graded on autistic skill just on content and making sure everything is correct So four energy levels and put those two valence electrons in first and valence electrons are the ones in the outermost energy level They go in first So we know we have to have 20 total electrons We've already got two of them done. So we have 18 left to go Work your way down to level number one get that one filled first the limit for level number one is two electrons 16 more to go Move on to level number two level number two can hold eight Leaves us with eight more to go The limit for level number three is 18. So all eight remaining electrons will fit easily into that level Six seven eight I can do those valence electrons first because if you don't you might be tempted to put all the remaining ten in level number three But by taking care of those two valence electrons first, we won't forget them And we'll make sure we get that third energy level written incorrectly Finally the stuff that you had to know from the notes what you have to learn what you have to memorize This isn't all of it There's other things in there like knowing that the nucleus of an atom has mostly atoms mass that the electron has most The atoms volume that the the electron cloud is mostly empty space that stuff Energy levels that the electron cloud is divided into energy levels and all the electrons in an energy level have similar energy The electrons level one have the lowest energy the electrons in level seven have the highest energy knowing the limits Slop number one holds two little number two holds eight number three holds 18 number four holds 32 Number five holds 50 knowing all those limits, too. There's a lot more than just this. This is a good chunk of it Relative size is large or small remember that your protons and your neutrons are your large particles They have considerably more size and mass than what an electron does about 1,800 times more mass than what an electron has Charge protons positive neutron has no charge and electron is negative and don't fall into that neutron negative trap neutron is neutral Rolled their jobs protons or identity They determine what atom and what element an atom is so if you have an atom with 35 protons in it That's the atomic number and that tells us bromine all Atoms with 35 protons are bromine if you had 36 it wouldn't be bromine anymore be krypton If he had 34 it wouldn't be bromine anymore. It would be selenium identity neutron is nuclear stability holds the nucleus together Protons have a positive charge and to jam them into a tiny space you have to have something that Overcomes the repulsion that they have the neutrons or what does that and for electrons its reactivity What determines how a substance reacts is how its electrons are arranged in its electron clouds specifically the valence electrons And then finally a location Both the proton and neutron Are in the nucleus? Where's the electrons in the electron cloud? Don't be that kid That misses the question that asks where are the electrons located? It's called an electron cloud for a reason Don't overthink it Again, there's more than that. Make sure you go through all the notes That's the application side of it, but make sure you go through all the notes So you know everything you need to know about energy levels everything you know about a nucleus The subatomic particles are made out of quarks and stuff so you can get a hundred on this quiz and start the quarter out with a good grade