in this video I'll talk about naming of ionic compounds before we discuss naming rules let's talk about the octet rule octet refers to eight electrons from OCTA and it's the driving force for All chemical reactions the octet rule says that atoms react by either giving or taking or sharing electrons in order to reach 80 electrons in their last energy level which is also called the principal energy level and atoms want to do that they want to reach 80 electrons in their last energy level in order to feel the stability of noble gases there are however some exceptions and here is the list of the exceptions that you need to know hydrogen cannot have eight electrons because it has only one proton in its nucleus hydrogen can have maximum of two electrons berum can have maximum of four electrons Bon and aluminum can have six electrons these four elements have less than 8 electrons sulfur on the other hand can have 8 10 or 12 electrons depending on what it reacts with and phosphorus can have eight or 10 electrons so sulfur and phosphorus can expand their octet they can have more than eight electrons and that has to do with the fact that they have D orbitals these D orbitals can accommodate extra electrons also keep in mind since we're talking about ionic compounds that Metals when react lose electrons and non-metals gain electrons let's look at a copy of the periodic table remember that uh we talked about this in a previous video there is a zigzag line that divides Metals which on the left of the zigzag line on on the left from non-metal switcher on the right again when not when metals react they lose electrons and they form positive charges when non-metals react they gain electrons and they form negative charges so let's talk a little bit more about that when metals lose electrons they form positive ions which are called cations I and we can figure out the charge that each metal forms when it reacts that charge equals to its group number for example lithium is in group one and that's why when it reacts it loses one electron and it forms a one plus charge um on your periodic table that hopefully you've already printed out I want you to write 1 plus right above hydrogen magnesium and calcium both belong to group two they are alkaline earth metals and when they react they lose two electron and they form a charge of 2+ go ahead and write two plus above berum group two metals do the same thing for group three Metals Boron and aluminum when they react they lose three electrons they form a three plus charge here's what happens to sodium when it under goes a reaction sodium has only one veence electron and we show that as a DOT next to the symbol of sodium sodium has total of 11 El Neons and 11 protons and where did we get this information from again from the periodic table here is sodium the number above sodium the atomic number tells us the number of protons and the number of electrons in sodium neutral sodium has 11 electrons one of these 11 electrons is veence electron and the other 10 are core electrons when sodium reacts it wants to lose this one veence electron and it gives it to a non-metal when that electron goes away now sodium has only 10 electrons and the protons didn't change the protons are inside the nucleus there's no change that takes place in the nucleus uh let's look at the overall charge initially 11 electrons which contribute a charge of1 versus 11 protons contributing a charge of positive 11 overall sodium atom has zero charge it's electronically neutral however at after sodium loses one electron and it has only 10 electrons outside the nucleus now the overall charge is one plus minus 10 from the electrons plus 11 for protons one plus charge here's what we do with the charge we place it in the upper right corner of the symbol and we always put the number first followed by the charge this is called the sodium ion it's not the sodium it's no longer the neutral sodium atom such as this symbol this is the sodium ion because it carries a charge and the charge equals to the group number sodium is in group one right here and that's why it forms a one plus charge let's do some more examples calcium is in group two it has a two plus charge rubidium is in group one forms a one plus charge if the charge is one you can place the one in front of it or you can Omid it one is optional aluminum is in group three it forms a three plus charge now let's talk about nonmetals when non-metals react they gain electrons and they form negative ions which are called anion and to figure out how many electrons and non-metal gains in a reaction you can do the following look at the group number of the non-metal and subtract eight from it and you obviously end up with a negative charge that's one way of figuring out the charge another way is to do the following figure out how many electrons a non-metal needs to reach an octet let's look at oxygen oxygen is in group six it has six veence electrons but it wants to have an octet it wants to reach eight electrons in its last energy level that means that it needs to gain two electrons that's why oxygen will have a two minus charge when it reacts uh let's look at nitrogen nitrogen is in group five it has five veence electrons in order to reach eight electrons in its principal energy level it needs to gain three more electrons remember that electrons carry negative charges and that's why nitrogen forms a three minus charge when it reacts it gains three electrons or you could use the group number nitrogen is in group five 5 - 8 is -3 oxygen is in group 6 6 - 8 is -2 which is the charge for oxygen let's look at a an example to see exactly what's happening in terms of electrons the Florine atom has total of nine electrons and nine protons it resides in group seven so it has seven veence electrons which are shown here is seven dots if you look at the initial charge nine electrons and nine protons overall there's no charge zero charge uh in a chemical reaction since Florine has seven electrons but it wants to have eight Florine will gain one electron and now there's total of eight veence electron in its last energy level if you look at the total count of electrons versus protons there's 10 electrons versus nine protons overall there is an negative one charge and again we can show the charge in the upper right corner of the electron symbol in the element symbol one is one minus this is no longer the neutral Florine atom instead it's called the fluoride ion notice how the ending is changed to IDE and we have to use the word ion because there's a charge every time you have an atom or a group of atoms that carry a charge positive or negative you have to use the word ion so now we're ready to talk about naming of ions and then naming of compounds let's start with naming of cations which are the positively charged ions to name a cation we need to name the metal and then we include the word ion here's an example mg2+ the metal is magnesium we write magnesium we don't worry about the charge that does it's not part of the name and then just include the word ion because there's the charge in the formula next k+ will be just potassium ion now let's do the opposite if you're given the name figure out the charge the formula aluminum ion here is a periodic table aluminum is in group three it forms a three plus charge I just realized I forgot to mention something else go back to your periodic tables right here and for group four elements right above carbon I want you to write four minus above nitrogen or group five nonmetals write 3 minus 2 minus for oxygen one minus for Florine these are the charges that nonmetals form when they react uh let's keep going with nonmetals calcium ion calcium is in group two it forms a two plus charge and lithium ion is group one element it forms a one plus charge again the one is optional now let's uh look at naming of annion or negatively charged particles for annion you need to list the non-metal name but you have to change its ending to ID and again we include the word ion because these are charged particles they have a plus or a minus charge which is part of their formula E3 minus comes from phosphorus phosphorus changes ending to ID becomes phosphide ion oxygen 2 minus turns into oxide ion hydrogen is hydride ion S2 minus is sulfide and F minus is fluoride let's do the following exercise where we have a mixture of C ions anion in neutral compounds BR minus this is an annion so it has to have the IDE and this is the bromide ion ba2 plus this is a cation we don't change the ending it's just barium ion SN notice there's no charge here this is a neutral atom neutral element tin if I say if I write down tin ion that would be incorrect I'm only allowed to use the word ion if there's a charge associated with the formula tin doesn't have a charge it's neutral that's why I omitted the word ion be2 plus is berum ion that's a cation C4 minus that's an annion carbide ion you have to change the ending to IDE hydrogen H+ is hydrogen ion W is one of the transition metals it's neutral it's just tungsten and H minus is hydride ion now I want you to pay attention to one thing here notice how H hydrogen could have a one plus charge or it could have a one minus charge if hydrogen is positively charged it forms a hydrogen ion if it's negatively charged it's called the hydride ion hydrogen is the only element from all the elements in the periodic table that can behave as metals and lose electrons like in this case or they can behave as nonmetals and gain electrons and that's why let's look at the periodic table again in some perod periodic tables hydrogen is shown in group one this is when it loses electrons and forms a one plus charge and some periodic tables also have hydrogen right here in group seven because hydrogen can behave just like a hallogen it can gain one electron and it can form a one minus charge there's no other element that can do that now let's move on to combining metals and nonmetals to form ionic compound compounds how do we recognize an ionic compound it contains a metal and a non-metal if the formula of the compound has only nonmetals then it's not ionic it's coent and we'll talk about calent compounds later if there's a metal and a non-metal that's an ionic compound here's examples sodium chloride sodium is a metal chloride is a nonmetal ionic compound pottassium oxide potassium is metal oxide is nonmetal that combination is an ionic compound in ionic compounds Metals give electrons to non-metals basically there is an electron exchange between an one atom from one atom to another but overall the ionic compound is neutral and it has zero charge here is a scheme that shows you how sodium chloride or table salt is formed sodium is a group one one metal it has only one valence electron chlorine is group seven it's a hallogen element it has seven veence electrons here shown as dots sodium loses one electron that one veence electron is lost and it's given to chlorine chlorine since it has only seven electrons it readily accepts that extra electron from sodium to reach an up that again sodium loses one electron chlorine gains one electron and the reason for that is they both want to have an octet what is the end result sodium now has a one plus charge and chloride since it has an extra electron has a one minus charge and notice how the plus and the minus neutralize each other and we can take this formula and just write it as NaCl this is the formula for sodium chloride basically we don't write the individual plus and minus charges that are part of the formula we know they're there we can just write the formula in its neutral form and let's do some exercises using C and anions here's the sodium ion which is the C and the sulfide ion let's figure out how we can combine these ions to form a neutral ionic compound so start by writing the formula for each ion sodium ion is na+ sulfide ion is is S2 minus and then ask yourself if I combine one sodium which carries a one plus charge and one sulfide ion would I end up with an electronically neutral compound 1 plus and 2 minus the charges don't neutralize each other we'll end up with a negative one charge so that doesn't work so what can we do to make sure that the charges are the same we can have two sodium ions if we add two sodium ions and combine that with one sulfide ion now we have a 2 plus charge that's contributed from sodium and 2 minus that comes from the sulfide ion that combination gives us an electronically neutral ionic compound meaning zero charge and since we're using two sodium ions the formula is na2s the two indicates that there's two sodiums as part of this uh compound and the two is always written as a subscript superscripts are charges like here we write the plus as a subscript as a superscript the 2 minus as a superscript but the subscripts indicate the number of atoms that are in the formula another way to figure out the formula is to use the crisscross method here's what it looks like start again let's look at the same problem we have sodium ions and we're combining sodium ions with sulfide ions we want to figure out the formula write the formula for sodium ions it's na1 plus write the formula for the sulfide ions S2 minus and then do the following take the charge of the metal and make it the subscript of the nonmetal take the charge of the non-metal and that will be the subscript of the metal basically the one goes next to sulfur the two goes next to sodium and that's the that's the formula the ionic compound formula for sodium sulfide what's important when you do this crisscross method is that these numberers right here the subscripts are the lowest they're in the lowest possible whole number ratio these numbers have to be whole you cannot have half a sodium atom or 1.5 sulfur atom they have to be whole numbers and the lowest possible ratio means the following right now we have a 2:1 ratio that's the lowest possible ratio if this was a 4:2 ratio then you have to further reduce these subscripts until you end up with the lowest possible ratio let's do another example calcium ions and oxide ions write the formula calcium has a 2 plus charge oxide a 2 minus charge we can combine these in a one: one ratio to end with to end up with a neutral compound calcium oxide or you could use the crisscross method where again we start with the formula of the cation and the anine and then we take the charge of the metal place it next to the nonmetal and the other way around with the nonmetal this is what we end up with ca2 A2 this is not the lowest possible whole number ratio so we have to further reduce these subscripts meaning we're going to divide both of these by two and the final formula is CAO again use reduction only when both subscripts are divisible by the same number in this case both are divisible by two aluminum ions and sulfide ions here I'll just use the crisscross method aluminum ion is al3+ sulfide ions is S2 minus when you do the crisscross method the formula is al2 S3 how do we name these ionic compounds the name of an ionic compound consists of the metal name plus the non-metal name but the non-metal name has to change its ending to I NAB is sodium bromide al203 aluminum oxide let's do the opposite now if you have the name you have to and you're asked to predict the formula in that case you have to apply the crisscross method let's start with the first name calcium iodide calcium has the following formula ca2+ and if you're wondering how I got these charges and I iodide has a one minus let's go again to the periodic table keep calcium is in group two and that's why it has a two plus charge iodide is right here it has a 1 minus charge I use the crisscross method I don't have to further reduce this the formula is c a I2 and you can look at the rest let's do the last one gallium hydde the formula is g83 Plus for gallium ion and hydride is H1 minus the IDE ending tells you that you have to use the hydro form that forms a negative charge or the anionic form of hydrogen do the crisscross method and that's the formula some more examples here and I will stop here before going into transition metals