Ionic and Metallic Bonding

Added: 2026-05-10

[00:00:03]all right guys so we're gonna go ahead and start on unit four unit four does cover bonding um so looking at how different atoms of elements come together to form compounds um so we're going to look at the different types of compounds and kind of how they form throughout this unit So today we're going to focus on ionic bonding and metallic bonding and we will pick up with molecular on Monday so for bonding anytime that we are forming a bond or compound we're dealing with the valence electrons of that substance so valence electrons are the electrons in the highest occupied energy level of an element's of an atom so whenever we were looking at for um electron configurations where we had like 2s2 P3 that second energy level is our highest energy level so we were counting how many electrons are in that highest energy level which here would be a total of five um instead of having to draw out the electron configuration every time and you can actually find the number of valence electrons in representative elements by looking at the group number and you're going to be looking at the Roman numeral group number so where it says like 2A 3A 4A in Roman numerals that's what we're looking at um the only exception where the number of valence electrons is not equal to the group number is helium helium is in group 8A in the noble gases but helium only has a total of two electrons um but it's in that same column because that energy level is full um so if you look at oxygen oxygen is in group 6A so it has six valence electrons nitrogen is in group 5A so it has five valence electrons if you were to look at aluminum it's in group 3A so it has three valence electrons so you can match up the valence electrons to that group number on the top this only works for the representative element so those first two columns and then the last six transition metals are different because they have that d block um we're not going to have to deal with transition metals at our stage that goes more into the AP level so like I said we're going to look at ionic compounds um so remember when we are forming ions we talked about this last unit or excuse me the unit before as well but whenever something forms ions it does so because it changes the number of electrons that it has and the electrons that it changes are those valence electrons so it either gains valence electrons or loses valence electrons in general atoms tend to be neutral because they have the same number of protons and electrons but remember if these are not equal to another it's either going to be a cation or an anion so remember cations are positively charged ions that form whenever an atom loses valence electrons so it loses valence electrons giving it a positive charge whereas anions are negatively charged and they form when an atom gains valence electrons so since there's more electrons has that negative charge so we will look at drawing dot structures for these um in a little bit but you're either taking away the electrons that are already there or adding to the number of electrons to give us a full energy level all right so looking at ionic bonding ionic is the more common one that we come across simply because it is dealing with bonding with metals and most of the elements on the periodic table are metals um so with ionic bonding these are ionic compounds are composed of cations and anions are referred to as ionic compounds um so it has something with a positive charge and something with a negative charge the opposite charges are what cause it to bond these are neutral after combining so your positive charges and negative charges are going to cancel out making it neutral um ionic compounds are going to be composed of a metal and a non-metal so metals tend to have that positive charge non-metals tend to have our negative charge an ionic bond itself is an electrostatic or magnetic force that holds ions together and ionic bonds so it's just that attraction between the positive and negatively charged ions and these are written out using chemical formulas so we use our symbols on the periodic table with subscripts to tell us how many of each of these we have so they do have a set formula we know exactly what is in an ionic compound and we write these out with the chemical formula showing the number of atoms of each element in a compound so like table salt is NaCl that means that there's one sodium and one chlorine and table salt the smallest part of an ionic compound is a formula unit this is the lowest whole number ratio of ions in an ionic compound so it'll tell us if we need two calciums or excuse me that's a bad example we might need three calciums to pair up with two nitrogens so that the charges balance out um but that three to two ratio is considered that formula unit so just looking at the number of atoms in an individual particle of that compound and we haven't done naming of compounds yet but subscripts should not be divisible by the same number um so we want it to be the lowest whole number ratio so if we have two calciums pairing up with two oxygens we could simplify that to be one calcium pairing up with one oxygen and you'll see this a bit more when we start drawing out these compounds and then next unit when we do nomenclature so ionic compounds how they're arranged is they are a crystalline solid and they're arranged in a lattice of positive and negative ions so it's going to be alternating positive and negative ions that are going to be attracted to every ion around them which just gives it this large 3D structure that you can see to the right um and layers of the lattice are stacked on top of one another um so here's an example of table salt you can see there are multiple layers of atoms going front to back and side to side it's alternating positive and negative charges and that allows it to be more stable we don't have to know the specific structure that's this point in time that does come up in later courses so another thing that we look at is not only identifying if a compound is ionic metallic or molecular we also look at properties of those types of compounds and that's one way that you can tell if something is ionic or molecular or metallic is based off of the properties ionic compounds like I said are usually crystalline solids at room temperature making them brittle so it almost looks like pieces of rock at this point in time at room temperature we can grind it into a powder but it is going to be a solid at room temperature and they're brittle so the particles can't really move around a lot the atoms or ions cannot so if you were to hit them with a hammer it shatters into a bunch of pieces um one of the main things that we will look at for determining um what type of compound is the melting point and boiling point um ionic compounds generally have high melting points and high boiling points these tend to be solids at room temperature with very few exceptions so it takes a lot of energy to melt these into a liquid and even more energy to change these into a gas and ionic compounds can conduct electricity and heat but only in liquid form so if you have solid table salt and you pour it out on the table and hook a battery up to it nothing happens but as soon as you melt that salt or you dissolve it in water electrical current will travel through it that's why in the summer whenever we get those thunderstorms they make people get out of the pool and stuff because the pool the water contains the like chlorine and all of those dissolved ions they will conduct electricity so that's why they have to make people get out of the pool because since the ions are dissolved in that water electricity can flow through that water all right um on the flip side metallic bonds um we don't deal with as often this is probably the least common one that we deal with um but here we have the valence electrons of metal atoms can be modeled as a sea of electrons so the electrons are able to move from one atom to the next so we end up um with a metallic bond is the attraction of free-floating valence electrons towards positively charged metal ions so we end up having ions and their electrons are floating around and their electrons can simply hop from one atom to the next and move around they are not locked in place on that particular cation um Lisa we do not deal with metallic very often um it exists and it's around us all the time but we do not use it for application purposes um in terms of metallic bonds metallic substances or metals also have high melting points and boiling points they also tend to be solids at room temperature with the exception of mercury which is a liquid at room temperature um one thing that separates metallic and ionic because they both had high melting points and boiling points is for metallic bonds they're good conductors for electricity and heat because the electrons are flowing freely through the substance when the electrons are a Charged particle is moving through the substance heater electricity can move through the substance so since the electrons are hopping from one atom to the next heat or electricity will hop from one atom to the next so that's why a lot of metals we use in cookware and stuff like that because the heat will flow through it rather easily this also allows metals to be drawn into wire or beaten into sheets so like we get aluminum foil because we're able to move around those individual cations and these also metallic luster luster you probably haven't heard of since earth science but it's just looking at the shininess of whatever substance we're looking for uh so metallic luster means that it is shiny it refracts light overall so ionic and metallic have very similar properties the one noticeable difference is that ionic can only connect electricity as a liquid whereas metallic can always conduct electricity you do not have to know the crystalline solids so we are going to skip that part just know that atoms don't have to be arranged the exact same from one substance to another all right with metallicons we also encounter Alloys you may be familiar with Alloys but may not know that the term matches up with what you know of but Alloys are a different type of mixture they're composed of two or more elements at least one of them being a metal so it's going to be a mixture of metals or metal with something like carbon silicon things like that Alloys are important because their properties are often superior to the component element so whenever you have a metal by itself it may not be as strong as whenever it's mixed with other elements overall some common examples of Alloys are something like brass bronze and cast iron stainless steel surgical steel um and things like that and the whole reason they make these alloys is because like we said their properties may be superior to other individual elements so these tend to be used in buildings and other structures as reinforcement when building a building a lot of times they will use steel beams to help support the weight of the other materials steel has a lot of different elements in it but it's stronger when all of the elements are mixed together and combined um all right so one thing that we're going to have to do is be able to notice or Draw dot structures for different types of elements ions and compounds that we're dealing with whenever we are drawing dot structures we are always looking at the valence electrons so only those outermost electrons um and like I said today we're going to focus on the ionic and metallic so we don't have to draw metallic um and then tomorrow we will look at the molecular covalent compounds that we come across so touching base since I did say remember we are only using valence electrons here remember that the valence electrons for an element is equal to the group number it is n so you're looking at the Roman numeral up above the column that that element is in whenever we are drawing dot structures of atoms or ions and we're going to do some examples from your homework sheet together you write the symbol of the element in the center and around that you're going to draw dots representing the valence electrons and they will eventually be drawn in pairs now this kind of ties back into our electron configurations a little bit but we're only looking at the valence electrons that outermost row so whenever we draw a symbol there are four kind of locations around that symbol where we are going to be putting electrons it doesn't matter the order that you fill these in or where you start but kind of like Hun's rule that we did with orbital diagrams you need to put one electron in each of these four places before going back to pair them so we'll do a couple examples and you'll see what I mean there um so on your homework sheet you have the big table and the first row of the table on the left has like the calcium atom then next to it is calcium ion there's the fluoride ion oh wait no just floor ing sorry I skipped one so fluorine then the fluoride ion and I'm gonna do um oxygen as an extra one I believe it's a couple rows down just you can kind of see another example so we're gonna do these five together um so starting with calcium if you find calcium on the periodic table calcium symbol is CA and we need to figure out how many valence electrons calcium has so if you put your finger on calcium which is number 20. scroll up it is in group 2A and I'll write this here so you can kind of follow along so group 2A remember is going to have two valence electrons so I'm going to draw two valence electrons around calcium but remember I cannot pair them until all four of my spots all four kind of quadrants have electrons so calcium is going to have two lone electrons that are not paired up together that is the entire Dot Structure for calcium now looking at the calcium ion remember an ion has a charge um and charges one thing that you can do to find the charges are by looking at the location on the periodic table sorry I'm gonna sketch it out real quick I'm leaving out the transition metal first case um the charges of atoms deal with how many valence electrons it will lose or gain so calcium has two valence electrons um metals are going to form cations and lose electrons so if calcium has two electrons to lose it will end up with a positive two charge so the calcium ion just means that it took that calcium got rid of those two valence electrons and this has a positive two charge once we get rid of those two electrons so with the ions a lot of times you will see them in Brackets or you will see them without brackets either way is fine for me but recognize that you may see it both ways so one thing is cations lose that outer layer worth of electrons so these end up being empty so these do not have dots around them whenever they are ions because that inner layer is full but the outer layer does not have valence electrons looking at fluorine Lorena is number nine on the periodic table fluorine has a symbol of f and it is in group 7A mean that it has seven valence electrons so remember we put one in each location before going back and pairing them so fluorine you're going to notice has three pairs of electrons and one lone electron now in terms of charges here so we said like um where hydrogen is they have one valence electron that they can lose that would be a plus one um where Boron is that column has three valence electrons it will lose those three valence electrons with our non-metals non-metals are more likely to form anions which have a negative charge because for flooring the whole point is we are trying to have the same number of electrons as a noble gas so fluorine is trying to have the same number of electrons as Neon meaning it has to gain one electron trying to fill up that outer layer well noble gases are going to have a charge of zero they are already going to have full energy levels so they tend to not bond with anything fluorine has seven valence electrons in order to have the same number as neon it needs to gain an electron meaning that it will have a negative one charge so the fluoride ion will gain that extra electron have a negative one charge you'll sometimes see the charge written on the outside sometimes you'll see it written on the inside just kind of pay attention to that delay said non-metals are trying to gain enough electrons to have the same amount as a noble gas so let's look at oxygen and if it doesn't have that IDE ending it is just an atom the IDE ending means that is going to be an ion so you'll notice that on your homework they are separated into columns where you have like a column of a metal a column of the metal ion a column of the non-metal and then a column of the non-metal ion looking at oxygen oxygen is in group 6A so it has six valence electrons oxygen has a symbol of o and if we put the six electrons around there there's four to put one in each spot and then we're going to have two that have a pair and it doesn't matter which two you pick to pair I tend to just go Clockwork clockwise just out of habit so notice here we have two paired pairs of electrons and then two lone electrons if you drew these together that is incorrect so make sure that you put one electron in each before going back and pairing and the whole premise for y substances bond is all about stability um and so for atoms or ions to have stability they need to obtain the octet rule um so for the octet rule it says that atoms tend to gain lose or share electrons until they have a total of eight valence electrons so either the inner layer has eight or you make it to where that outer layer has eight the exception is hydrogen and helium because they're so small they can only have up to two total valence electrons um so everything tries to have eight valence electrons Except for hydrogen and helium so you'll notice um if you look at the periodic table in the top left um everything in the same column has an identical Dot Structure with the exception of helium um you can find the charges based off of whatever like how many it needs to lose so that that inner layer has eight or how many it has to gain so the outer layer has to have eight um and these will bond and share electrons in order for them to have eight and the picture on the right deals with a covalent compound so we will deal with those on Monday but the whole purpose is to make sure that every atom or ion has the same number of valence electrons as a noble gas so looking at ionic compounds how we sketch these out um is with ionic compounds there's a transfer of electrons that goes on so something loses electrons while something else gains electrons electrons aren't just floating out in space so the substance that loses an electron actually gives it to the anion that gains an electron so that's what allows them to pair up so here if you notice we have sodium sodium would have one valence electrons just one dot chlorine is in that same group as fluorine so it will have seven valence electrons so sodium since it's a metal is trying to lose that one because it's easier to lose one valence electron than to gain seven for it to have eight so it will simply transfer and give that electron to chlorine making it a sodium ion and a chloride ion and that positive negative is what attracts those together in a compound so how ionic compounds form is they transfer electrons to form that Bond and how we represent that transfer of electrons is with that arrow that I drew foreign so let's look at a couple examples of how we draw ionic compounds um so here I have two examples of magnesium and fluorine and since we haven't done nomenclature the formula will be given to you or you're trying to figure out like how many of each you need magnesium fluoride is going to be ngf2 so we have two magnesiums or excuse me one magnesium and two fluorines and how these pair up so magnesium is in the second column on the periodic table so it has two valence electrons fluorine is in that group seven eggs we said it has seven valence electrons so how we show that these bond together is remember our metals are trying to get rid of all their valence electrons so that the inner layer is full while our non-metals are trying to gain enough to have the same as a noble gas so the Magnesium is trying to get rid of two valence electrons while fluorine since it has seven needs one more so magnesium will actually give an electron over to fluorine now fluorine is full with eight but magnesium still has one more electron to get rid of that's why there's a second fluorine so it will give up that second electron to that second fluorine that is the Dot Structure for an ionic compound so it does need to be shown like this where it shows the dots and the arrows showing the ionic compound last one let's look at when we have aluminum and oxygen and the formula here is going to be al2o3 meaning that we have two aluminums and three oxygens aluminum is in group 3A so it has three valence electrons so I'll draw them on both aluminums oxygen has six valence electrons so we drew that one a minute ago so remember we have two pairs and two that are by themselves so aluminum has three electrons that it has to get rid of the oxygen since it already has six valence electrons can only take two more so aluminum can give two electrons to this oxygen so now that first oxygen is full but aluminum still has one more electron to get rid of so it can give that electron to the second oxygen so now that first aluminum is empty but now the second oxygen only has seven it still needs one more that's why there's an additional aluminum so it will give oxygen that last electron it needed but now aluminum has two more electrons that it needs to get rid of which is where the third oxygen comes in so it can transfer those missing electrons so on your homework you're looking at that page that has the big tables the table on the left is drawing the atoms and ions sorry and the table on the right is drawing on it compounds you must draw them with the arrows showing that transfer of electrons and we will pick up Monday with molecular compounds