How to Use Electronegativity to Determine Bond Type | What Type of Bond is it | Bond Type tutorial

Summary

In this video, Mrs. Cash explains how to use electronegativity to determine bond types between atoms. Electronegativity is defined as an atom's ability within a molecule to attract shared electrons. Elements with higher electronegativity values, particularly those in the top right corner of the periodic table like fluorine, are more likely to attract electrons. The video covers various bond types, including nonpolar covalent bonds, where electrons are shared equally between atoms, and polar covalent bonds, where electrons are shared unequally. It also touches on ionic bonds, which occur when electrons are transferred between atoms with significant electronegativity differences, typically between metals and nonmetals. Examples of different bond types and their characteristics are discussed throughout the video.

Highlights

• Electronegativity is highest in the top right of the periodic table, with fluorine being the most electronegative. 📈
• Nonpolar bonds share electrons equally, seen in identical nonmetals like H2 or Cl2. 🔗
• Polar bonds have atoms pulling electron density unevenly, as seen in H-F bonds. 🎯
• Ionic bonds transfer electrons, often between metals and nonmetals, creating charged particles. ⚖️
• Understanding electronegativity helps in predicting the behavior and interaction of different molecules. 🔍

Key Takeaways

• Electronegativity helps determine if a bond is polar, nonpolar, or ionic. 🤔
• Nonpolar bonds occur when atoms share electrons equally, often between two identical nonmetals. ⚖️
• Polar bonds involve unequal sharing of electrons due to differences in electronegativity. 🎭
• Ionic bonds result from electron transfer between metals and nonmetals, leading to charged ions. ⚡
• Electronegativity values and periodic table positioning help predict bond types and polarities. 📚
• Molecules can have characteristics of both ionic and covalent bonds depending on the context. 🔄

Overview

Electronegativity is a key concept in chemistry when determining the type of bond that forms between atoms. It's a measure of how strongly an atom can attract or hold onto electrons within a molecule. In the periodic table, electronegativity increases towards the top right, excluding noble gases. Fluorine stands out as the most electronegative element with a value of 4.0, making it critical in many chemical bonding scenarios.

There are three primary types of bonds to consider: nonpolar covalent, polar covalent, and ionic bonds. Nonpolar covalent bonds involve equal sharing of electrons often between two identical nonmetals. In contrast, polar covalent bonds display unequal sharing due to differences in electronegativity, creating dipoles with partial charges. Ionic bonds occur when there is a significant electronegativity difference, usually between metals and nonmetals, leading to a transfer of electrons and formation of charged ions.

The video explains these concepts through various examples, emphasizing that bonding is not always clear-cut. Many covalent bonds exhibit some ionic characteristics, especially in cases of polar bonds. Understanding these bonds helps in predicting molecular behavior, interactions, and properties, equipping viewers with the knowledge to tackle related chemistry problems effectively.

Chapters

• 00:00 - 00:30: Introduction to Electronegativity and Bond Types The chapter introduces the concept of electronegativity and its role in determining the type of bonds between two atoms. It explains that electronegativity is the ability of an atom within a molecule to attract shared electrons. The chapter notes that electronegativity is highest in the top right corner of the periodic table, excluding noble gases, with fluorine being the most electronegative element with a value of 4.0.
• 00:30 - 02:30: Bond Polarity and Nonpolar Covalent Bonds Bond polarity explains the sharing of electrons between atoms in a covalent bond. Covalent refers to the sharing of electrons, which is not always equal, leading to bond polarity. This inequality in sharing depends on electronegativity. A nonpolar covalent bond is a type of covalent bond where electrons are shared equally between the two atoms in the bond, mainly due to similar electronegativity values.
• 02:30 - 06:00: Polar Covalent Bonds and Electronegativity Differences The chapter titled 'Polar Covalent Bonds and Electronegativity Differences' explains the concept of electronegativity and its role in the sharing of electrons between atoms. It emphasizes that for electrons to be shared equally, the electronegativities of both atoms must be identical, resulting in an electronegativity difference of zero. This situation is typical in bonds between two identical nonmetals, such as in diatomic molecules like H2, where hydrogen atoms have equal electronegativity.
• 06:00 - 12:10: Ionic Character and Dipoles in Covalent Bonds This chapter discusses the concept of ionic character and dipoles in covalent bonds. It starts by explaining that when two identical atoms form a bond, such as in diatomic elements, the bond is typically nonpolar. This can also apply to larger molecules like hydrocarbons where similar atoms are bonded. However, the chapter notes that there are exceptions where some elements, even if identical, exhibit slight differences in electronegativity leading to a polar bond. The chapter emphasizes the importance of understanding the nuances in electronegativity that contribute to the behavior of bonds.
• 12:10 - 15:00: Intermolecular Forces and Bond Continuum The chapter discusses the concept of intermolecular forces and the bond continuum, focusing on the role of electronegativities in bond formation. It explains that bonds can occur between two different nonmetals with the same or very similar electronegativity values, resulting in nonpolar bonds. Some textbooks define nonpolar bonds within a range, such as 0.4 or less. The chapter emphasizes that specific memorization of these ranges is not necessary, but rather understanding that similar nonmetals bonded together will form nonpolar bonds.
• 15:00 - 18:00: Bond Type Determination Summary This chapter explains how to determine whether a chemical bond is nonpolar. It emphasizes that a bond between hydrogen and carbon is generally considered nonpolar, despite a slight difference in electronegativity (about 0.4), as the difference is negligible. It is also mentioned that a bond between two identical elements, such as carbon-carbon, is nonpolar due to identical electronegativity.
• 18:00 - 23:00: Practice Examples and Calculating Electronegativity Differences The chapter focuses on practice examples and calculating electronegativity differences. It explains that a bond between carbon (C) and hydrogen (H) is considered non-polar. Memorizing elements with identical electronegativity isn't necessary, but if values are provided, bonds with identical electronegativity can be deemed nonpolar. The chapter also addresses identifying nonpolar bonds by seeking the smallest possible electronegativity difference, close to zero. Conversely, it mentions that a polar bond is different from nonpolar bonds, without going into specifics.
• 23:00 - 27:30: Polyatomic Ions and Mixed Bond Types The chapter discusses the concept of covalent bonds where electrons are shared between atoms but not equally. It highlights the role of electronegativity in determining the polarity of a bond, stating that a difference in electronegativity between atoms leads to polar bonds. It notes that different sources may provide varying ranges for the degree of polarity, but generally, any non-zero difference marks an increasingly polar bond.

How to Use Electronegativity to Determine Bond Type | What Type of Bond is it | Bond Type tutorial Transcription

• 00:00 - 00:30 this video we're going to take a look at electronegativity and how to use that to figure out the type of bonds between two atoms so if you recall electronegativity is the ability of an atom in a molecule to attract two shared electrons to itself we said that electronegativity was the greatest in the top right hand corner of the periodic table excluding the noble gases so fluorine is the most electronegative atom with a electronegativity of 4.0 we can use
• 00:30 - 01:00 electronegativity values to determine the type of bonding that's present so bond polarity describes the sharing of electrons between atoms in a covalent bond so if you see the word covalent that means you have a sharing but this type of sharing is not always equal and that gives way to bond polarity so this is going to depend on electronegativity so in nonpolar covalent bond electrons are shared because it's covalent and they are shared equally between the two atoms in your bond so essentially in
• 01:00 - 01:30 order for electrons to be shared equally both atoms have to have the exact same attraction for bonding electrons and what is the attraction for bonding electrons called oh that's electronegativity so essentially this is when your electronegativities of each atom are equal or essentially the difference is zero when will this always happen this will always be the case when you have two of the same nonmetals so for instance if you have an H bonded to an H like in your molecule of diatomic
• 01:30 - 02:00 h2 if you have two Ciel's bonds together two ends bonded together this can happen in a small molecule like these diatomic elements or this might happen in a larger molecule like two carbons bonded together in a large hydrocarbon okay it's important to note that though typically we're going to look at nonpolar bonds as between two of the same element there are some elements that have almost equal
• 02:00 - 02:30 electronegativities so it could be bonded between two different nonmetals that happen to have the same electronegativity or that happen to have a very very small difference in electron so some textbooks actually define nonpolar as not just being zero but they give it a range of like 0.4 and less than that so you don't really need to memorize this range essentially if you see two nonmetals that are the same bonded together you know that it's going
• 02:30 - 03:00 to be nonpolar the but what you should memorize is that hydrogen and carbon a bond between those is always considered to be nonpolar even though the difference is about point four so it's not exactly zero the difference is pretty negligible so for what you should know is again if you see two like here's here's a see bonded to a see that's a non-polar bond because it's between two elements that have the exact same electronegativity you should know if you
• 03:00 - 03:30 see a C bonded to an H we also consider that to be a non-polar bond otherwise you don't have to memorize other elements that happen to have the same electronegativity but if values happen to be given and you do see that two elements have the same electronegativity then you could assume the bond to be nonpolar or they might ask which of the following is nonpolar and you're looking for the smallest difference that's closest to zero as possible a polar bond is since this
• 03:30 - 04:00 covalent electrons are shared but they are shared unequally essentially one atom is going to attract electrons a little more than the other atom so this happens when your electronegativities are not equal or the difference is greater than zero again some textbooks have these exact finite ranges however they vary from source to source so it's not really accurate so really anytime your difference is greater than zero you have an increasingly polar bond the
• 04:00 - 04:30 further it is from zero the more polar the bond is so when will this be the case well this will obviously be the case when you have two different nonmetals bonded together like a C and an O or an H and an F okay essentially the electrons are going to hover closer to one atom than the other because one atom will pull a little harder on electrons and the other the greater the difference in electronegativity the further it is from zero the more polar the bond so let's take this scenario of
• 04:30 - 05:00 HF so when I'm looking at H and F it's a non polar of excuse me it's a polar bonds two different elements with two very different electronegativities which I can actually look up the values and see they're very different fluorine has an electronegativity of about four hydrogen has an electronegativity of about 2.1 so which might vary depending on the source in accuracy so if I'm looking at this bond I can indicate the
• 05:00 - 05:30 polarity of it over the bond in two different ways they can give this Greek lowercase Delta sign it looks kind of like 3/4 of an eighth and it kind of means partial so if I give this Greek Delta and a-plus over something that means it's partially positive and if I put this Delta negative it means slightly negative so in the HF bond okay whichever is less electronegative is gonna get the partially positive and
• 05:30 - 06:00 whichever is more electronegative gonna get the partially negative so since fluorine is more electronegative I can show that this is the partially negative side of the atom electrons are gonna hover closer to this high up fluorine and it's gonna give a partial negative charge to the fluorine it's not a full negative charge the electrons are still shared but they are quote the electron density is closer to fluorine and I can give a partial positive to the hydrogen another way I can indicate polarity oh and just as a note the partial part
• 06:00 - 06:30 charges should cancel each other out to add up to the total charge on the molecule so plus minus cancel out to be neutral or another way you can show this is just giving an arrow to show the shift in the electron density so I'm just showing that electrons are hovering closer to the fluorine so I would put an arrow pointing toward the fluorine so either one of these is perfectly acceptable if they asked you to show the polarity of the bond you will see that I typically gravitate toward the partial
• 06:30 - 07:00 charges when we do formal charges we put little charges above Adams so I just kind of feel like it goes along with that pretty nicely okay since there's partial charges we can kind of see that some of these covalent compounds and these covalent bonds are going to have an ionic character to them as well so it's really not always just cut and dry something's ionic something's covalent there's there's a continuum between them okay we can call
• 07:00 - 07:30 molecules that have one partially positive end and one partially negative end to be dipoles or we say they are dipolar or they have a dipole moment those are all synonyms of each other to indicate that you have a molecule where you have one end positive and one and negative and again the greater the electronegativity difference the greater the dipole moment what you'll start to notice is if I have two molecules one
• 07:30 - 08:00 side is negative and the other side is positive they're gonna start ending up attracting each other in certain ways and intermolecular forces are going to start happening and that's what we'll see when we get to the intermolecular force chapter take a moment and I want you to draw three water molecules in the Box using this key and show the correct orientation to each other with respect to their partial charges so if you're doing this okay here's a water molecule
• 08:00 - 08:30 one oxygen for two hydrogen's don't be that person that has it backwards and just two oxygens for one hydrogen I drew it looking bent and we'll see in terms of geometry why later so my my hydrogen's are partially positive just to show that charges are balancing out I'm gonna put two next to my partial negative charge if you prefer to just put a partial negative by this oxygen and a partial one in just one partial positive over here that's fine but I want to make sure that my partial
• 08:30 - 09:00 charges cancel out to zero so if I have another hydrogen coming along all I want to make are another water coming along I just want to make sure that the hydrogen ends are aligning with the oxygen end so the positives and negatives are attracting each other okay so anything that kind of shows the positive hydrogen partially positive hydrogen's aligned with the partially negative oxygen okay take a moment and try this example so this is Cu 2 plus alright if I have a
• 09:00 - 09:30 water molecule which is a polar molecule the oxygen is more electronegative than the hydrogen so the oxygen will have a slight negative charge and the hydrogen's will have slight positive charges so the oxygens would be aligned toward the Cu 2 plus so the hydrogen's should be out and the oxygen side should be facing in if we're looking at nayana crime but it's just typically between metals and nonmetals metals have low electronegativity nonmetals have high electronegativity nonmetals have such
• 09:30 - 10:00 larger electronegativity than the metals that they actually steal the electron from the metal or the electrons actually transfer to the nonmetal again the greater the electronegativity difference between the metal and nonmetal the greater in this case we say the ionic character we don't say it's more polar because it is not a covalent bond it is not polar but we can say it has a greater ionic character and again just a mention of the continuum of bonds all polar covalent bonds have some ionic
• 10:00 - 10:30 character to them as we show with those partial charges and ionic bonds have some covalent character to them as well so the difference is not cut and dry it's not distinct it's rather a continuum electronegativity is not the only factor and just for example bcl-2 okay you would see that b/e is a metal and seals and nonmetal and at first glance you would probably think this is ionic and in fact this is actually covalent be2 plus if we look at it it
• 10:30 - 11:00 has a really high charge to it okay and it has a small radius there's only two shells to it so there's a really strong Kalama force of attraction for electrons so any electrons that it would transfer to the CL minuses are actually pulled back which introduces covalent care and it kind of shares electrons rather than having it transfer to the CL so this is in fact covalent so you can kind
• 11:00 - 11:30 of explain this in terms of what we learned about periodicity last chapter I wouldn't expect you to maybe right now just know offhand that that was covalent okay so in summary to distinguish bond type used electronegativity difference nonpolar means electrons are shared equally the difference is zero as well typically between two of the same nonmetal element like two seas or two H's remember that we said CH it's also considered a non-polar bond polar is
• 11:30 - 12:00 when electrons are shared unequally the difference in electronegativity is greater than zero when I have two nonmetals bonded together this will typically be two different nonmetal elements ionic bond is when electrons are transferred the difference in electronegativity is greater than zero when you have a metal and nonmetal typically take a moment and try this example okay H and O are two different nonmetals so it's a covalent bond and it would be polar these are two nonmetals that are the same so this would be
• 12:00 - 12:30 nonpolar na and F ionic metal nonmetal this is two nonmetals they are different so it's polar this is a metal and a nonmetal so I would say that's ionic these are two of the same nonmetals joined together so I'm nonpolar here is a two nonmetals that are different polar for one through seven which is the most polar bond and without actually having values in front of me I can kind of see well where on the periodic table are these things and which are spread furthest from each other and I would say
• 12:30 - 13:00 H and O H has a relatively low electronegativity is around 2.1 and O is the second most electronegative element when I say which has the greatest ionic character now I can start to consider my ionic compounds to I don't want to pick something ionic for most polar because I'm looking for something covalent by the word polar so I would choose na and F which would have the largest difference just kind of seeing where they're located on the periodic table
• 13:00 - 13:30 and the difference between them which has electrons transfer that's the definition of ionic which has electrons shared equally that's the definition of nonpolar covalent and which have electrons shared unequally that's the definition of polar covalent take a moment and here now I'm giving you electronegativity values which of the following is most polar so if I'm doing this I want to actually calculate the difference for each of these if I'm calculating the difference I'm essentially want the absolute value of
• 13:30 - 14:00 the difference so it doesn't matter in my bond which is first in which is second you're just kind of always subtracting the higher number minus the lower number or just taking the absolute value of the difference so here I'm always showing it with a higher number minus the lower number and I noticed that here are my electronegativity differences the most polar would be the greatest difference the least polar would be the lowest difference take another moment to try this example out
• 14:00 - 14:30 of all of these E is really the only one that has a metal and nonmetal so automatically I would say that this is the most ionic take a moment and try this example notice I don't have electronegativity values in front of me but they are all bonded to the same element H so I can see essentially which one of these elements is most electronegative using my trend and I would say oxygen it's helpful to know
• 14:30 - 15:00 that fluorine is the most electronegative and oxygen is the second most electronegative element as well okay question which kinds of bonds are within polyatomic ions such as nitrate so within nitrate the N is covalently bonded to the O it's two non I should say N and O it's two nonmetals and they are two different nonmetals with different electronegativities so these
• 15:00 - 15:30 would be covalent bonds between the N in the O it just happens to have a charge to it because there's one more electron within this molecule that's shared within this molecule that would allow it to also ionically bond so if I have an ionic compound like in this next question that contains a polyatomic ion there will be two types of bonds here there would be covalent bonds between the N and the O in nitrate
• 15:30 - 16:00 and there would be Yannick bonds between the calcium 2 plus and the nitrate ions forming an ionic compound so if you see a polyatomic ion within an ionic compound that molecule or that compound I should say contains both ionic and covalent bonds