Chemical Bonds: Covalent vs. Ionic

Summary

In this educational video, Mr. Andersen delves into the world of chemical bonds, explaining the fundamental types: covalent (both polar and non-polar) and ionic. He uses the analogy of collecting Star Wars action figures to illustrate the octet rule, emphasizing atoms' desire to complete their outer electron shell. The concept of electronegativity is introduced to differentiate between bond types, with examples provided to demonstrate how to calculate and identify polar covalent, non-polar covalent, and ionic bonds.

Takeaways

• 🧲 Chemical bonds are attractions between atoms or molecules, and they can be covalent, ionic, or metallic in nature.
• 🔁 Covalent bonds involve the sharing of electrons between atoms, with two subtypes: polar and non-polar, depending on the equality of electron sharing.
• 🌊 Polar covalent bonds occur when there is an unequal sharing of electrons, leading to a difference in electronegativity between the bonded atoms.
• ⚖️ Non-polar covalent bonds occur when electrons are shared equally, resulting in no significant difference in electronegativity between atoms.
• 💧 An example of a polar covalent bond is found in water (H2O), where oxygen and hydrogen atoms share electrons unequally.
• 🛢️ Non-polar covalent bonds can be seen in diesel fuel (C16H34), where carbon and hydrogen atoms share electrons equally.
• 💠 Ionic bonds occur when electrons are transferred between atoms, forming ions that are attracted to each other, as seen in table salt (NaCl).
• 🌌 The octet rule states that atoms tend to gain, lose, or share electrons to achieve a stable electron configuration with eight electrons in their outermost shell.
• 📊 Electronegativity is a measure of an atom's ability to attract electrons, with fluorine having the highest electronegativity and francium the lowest.
• 🔢 The type of chemical bond can be determined by the electronegativity difference between atoms: non-polar covalent (0.5 to 0.0), polar covalent (1.7 to 0.5), and ionic (above 1.7).
• 🚫 Metallic bonds are not discussed in the script, but they involve a collective sharing of electrons among metal atoms, contributing to properties like hardness and conductivity.
• 📚 Understanding electronegativity and the octet rule is crucial for identifying the type of chemical bond between atoms.

Q & A

What is the main topic of Mr. Andersen's lecture?

The main topic of Mr. Andersen's lecture is chemical bonds, specifically focusing on covalent bonds (both polar and non-polar) and ionic bonds.

What are the four different types of chemical bonds mentioned in the script?

The four different types of chemical bonds mentioned are covalent bonds (polar and non-polar), ionic bonds, and metallic bonds, although metallic bonds are not discussed in detail in this lecture.

What is the fundamental process occurring in a covalent bond?

In a covalent bond, atoms share electrons rather than transferring them to one another.

How does the sharing of electrons differ between polar and non-polar covalent bonds?

In a non-polar covalent bond, electrons are shared equally between the atoms. In a polar covalent bond, the sharing of electrons is unequal, with one atom having a greater attraction for the electrons than the other.

What is an ionic bond and how does it form?

An ionic bond is formed when electrons are transferred from one atom to another, resulting in the formation of ions that are attracted to each other due to their opposite charges.

Why are metallic bonds not discussed in this lecture?

Metallic bonds are not discussed in this lecture because the focus is on covalent and ionic bonds. Metallic bonds involve a different electron sharing mechanism where electrons are collectively shared among metal atoms.

What is the significance of the 'octet rule' in understanding chemical bonds?

The octet rule is significant because it explains the tendency of atoms to form bonds in order to achieve a stable electron configuration, typically with eight electrons in their outermost shell.

How does Mr. Andersen relate the octet rule to a childhood experience?

Mr. Andersen relates the octet rule to the desire of having a complete set of Star Wars action figures as a child. Just as a child wants to complete their set, atoms want to complete their outer electron shell.

What is electronegativity and how is it measured?

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. It is measured on a numerical scale, with values indicating the strength of an atom's pull on electrons.

How can you determine the type of bond between two atoms based on their electronegativity difference?

The type of bond can be determined by the electronegativity difference between the two atoms: less than 0.5 indicates a non-polar covalent bond, between 0.5 and 1.7 indicates a polar covalent bond, and greater than 1.7 indicates an ionic bond.

Can you provide an example of how to calculate the type of bond in water (H2O) using electronegativity values?

To determine the bond type in water, you would subtract the electronegativity of hydrogen (2.20) from that of oxygen (3.44), resulting in a difference of 1.24. This value falls within the range for a polar covalent bond.

Why don't diesel fuel and water mix?

Diesel fuel and water don't mix because diesel fuel contains non-polar covalent bonds, while water has polar covalent bonds. The principle of 'like dissolves like' applies, meaning that polar substances tend to dissolve in other polar substances and non-polar substances in non-polar substances.

Outlines

00:00

🔬 Introduction to Chemical Bonds

Mr. Andersen introduces the concept of chemical bonds as the attractions between atoms or molecules, distinguishing them from intermolecular bonds. He presents four types of chemical bonds, focusing on covalent bonds, which are further divided into polar and non-polar. Covalent bonds involve the sharing of electrons, with the degree of sharing varying from equal in non-polar to unequal in polar bonds. Ionic bonds, on the other hand, involve the transfer of electrons, leading to the formation of ions that attract each other, exemplified by NaCl. Metallic bonds are mentioned but not discussed in detail, as they involve a collective sharing of electrons within metals. The octet rule is introduced through an analogy to a complete set of Star Wars action figures, illustrating the desire of atoms to have eight electrons in their outer shell.

05:03

📚 Understanding Bond Types Through Electronegativity

This paragraph delves into the concept of electronegativity, which is a measure of an atom's attraction for electrons, and its role in determining the type of chemical bond formed. Electronegativity values increase across the periodic table from left to right and decrease as you move down the groups. The paragraph explains how to identify non-polar covalent, polar covalent, and ionic bonds based on the electronegativity difference between atoms. Using examples such as water (H2O), diesel fuel (C16H34), and salt (NaCl), the script calculates the electronegativity differences and classifies the bonds accordingly. Water is identified as a polar covalent bond due to its electronegativity difference of 1.24, diesel fuel as a non-polar covalent bond with a difference of 0.35, and salt as an ionic bond with a difference greater than 1.7. The summary also invites the audience to apply this knowledge to ammonia (NH3), prompting them to determine the bond type based on the provided electronegativity values.

Keywords

💡Chemical Bonds

Chemical bonds are the forces that hold atoms or molecules together. They are the fundamental interactions that determine the structure and properties of substances. In the video, Mr. Andersen explains different types of chemical bonds, emphasizing their importance in understanding how substances interact and form compounds.

💡Covalent Bonds

Covalent bonds are a type of chemical bond formed by the sharing of electron pairs between atoms. The video distinguishes between polar and non-polar covalent bonds, explaining that the sharing can be equal or unequal, which affects the properties of the molecules formed, such as water (H2O) having a polar covalent bond and diesel fuel (C16H34) having a non-polar covalent bond.

💡Polar Covalent Bonds

Polar covalent bonds occur when electrons are shared unequally between atoms, leading to a molecule with an uneven distribution of electron density. This creates partial positive and negative charges. In the script, water is used as an example of a molecule with polar covalent bonds, where oxygen pulls electrons more strongly than hydrogen, resulting in a molecule with distinct poles.

💡Non-polar Covalent Bonds

In non-polar covalent bonds, electrons are shared equally between atoms, resulting in a uniform distribution of electron density and no separation of charge within the molecule. The video uses diesel fuel as an example, explaining that the C-H bonds in C16H34 are non-polar because the electron sharing between carbon and hydrogen is equal.

💡Ionic Bonds

Ionic bonds are formed when electrons are transferred from one atom to another, resulting in the formation of ions with opposite charges that attract each other. The video uses NaCl, or table salt, as an example of an ionic bond, where sodium loses an electron to become a positively charged ion and chlorine gains an electron to become a negatively charged ion.

💡Electronegativity

Electronegativity is a measure of an atom's ability to attract electrons in a chemical bond. It is a key concept in the video, as it helps determine the type of bond formed between atoms. The higher the electronegativity difference between two atoms, the more likely an ionic bond will form. For example, the electronegativity difference between hydrogen and oxygen in water contributes to its polar covalent bond.

💡Octet Rule

The octet rule states that atoms tend to form bonds in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas. This rule is central to the video's discussion on chemical bonding, as it explains why atoms share or transfer electrons to achieve stability, like in the case of carbon and oxygen in CO2.

💡Metallic Bonds

Metallic bonds are a type of chemical bond found in metals, where electrons are not tightly bound to individual atoms but are shared collectively among all the atoms in the metal. Although not the main focus of the video, Mr. Andersen mentions metallic bonds to differentiate them from the covalent and ionic bonds discussed in detail.

💡Intermolecular Bonds

Intermolecular bonds are forces that hold molecules together, as opposed to chemical bonds that hold atoms within a molecule. While the video script mentions these bonds, it clarifies that the main focus is on chemical bonds within molecules, such as covalent and ionic bonds.

💡Electron Transfer

Electron transfer is the process by which electrons move from one atom to another, leading to the formation of ions. This concept is crucial for understanding ionic bonds, as seen in the video's explanation of how NaCl forms through the transfer of an electron from sodium to chlorine.

💡Star Wars Action Figures

While not a scientific term, the analogy of Star Wars action figures is used in the video to illustrate the octet rule. Mr. Andersen compares the desire of atoms to complete their outer electron shell with a child's desire to have a complete set of action figures, making the concept more relatable and easier to understand.

Highlights

Introduction to chemical bonds as attractions between atoms or molecules.

Differentiation between covalent, ionic, and intermolecular bonds.

Explanation of covalent bonds with a focus on polar and non-polar types.

Illustration of polar covalent bonds using the example of water (H2O).

Description of non-polar covalent bonds with the example of diesel fuel (C16H34).

Clarification on electron sharing in covalent bonds, from equal to unequal.

Introduction to ionic bonds through the example of NaCl (table salt).

Discussion on metallic bonds and their collective electron sharing in metals.

The importance of the octet rule in achieving a stable electron configuration.

Analogy of the octet rule to collecting Star Wars action figures for completeness.

Explanation of electronegativity and its role in determining bond type.

Criteria for identifying non-polar, polar covalent, and ionic bonds based on electronegativity differences.

Use of the periodic table to find electronegativity values for bond analysis.

Example calculation for determining the bond type in water (H2O).

Example calculation for determining the bond type in diesel fuel (C16H34).

Explanation of why non-polar and polar substances do not mix, using diesel fuel and water as an example.

Example calculation for determining the bond type in salt (NaCl).

Final example calculation for determining the bond type in ammonia (NH3).

Transcripts

Hi. This is Mr. Andersen. Today I am going to talk about chemical bonds. Chemical

bonds are attractions between either atoms or molecules. Now a little bit later we'll

talk about intermolecular bonds, so those are things that are attaching molecules together

but right now we're talking about straight up chemical bonds. In other words attractions

between atoms. I've pictured four of them on this diagram right here. Our four different

types are covalent bonds. So covalent bonds are going to be broken into two different

types. These ones right here would be polar, so I'm talking about the water itself or the

H2O. And then over here, this would be a non-polar covalent. Non-polar covalent, this is some

diesel fuel that's been spilled. It's actually C16H34. And so in a covalent bond what you're

doing is you're actually sharing electrons. You're not stealing electrons, but you're

sharing them. And it goes from sharing them very equally in a non polar bond to sharing

them very unequally in a polar bond. So these are the covalent bonds. Next one we'll talk

about are going to be ionic bonds. Ionic bonds. In ionic bonds bonds you're actually transferring

electrons between two different atoms and those become what are called ions. And those

ions are what are attracting it together. And so in this case we've got NaCl, or just

regular table salt. And that's an ionic bond. Now the other bond that's pictured here that

I won't talk about today are going to be metallic bonds. Metallic bonds are found within metals.

And they don't share their electrons. They kind of collectively share their electrons

so it gives them cool stuff like hardness and conductivity. And so we're not going to

talk about metallic bonds. But today I'm going to talk about covalent bonds, both non-polar

and polar and then ionic bonds. And mostly what I want to talk about today how do you

figure your what kind of bond it is. If you're just given the atoms, how do you know? Okay.

So I want to digress a little bit and talk about the octet rule in kind of a round about

way. When I was a kid, the most important toy you could have was Star Wars action figures.

Now I'm dating myself a little bit. In other words if you went over to a kid's house and

they had all these action figures it was going to be a great day because you knew they had

them all. And so what were the big ones? At least on the good side, the big ones you had

to have Chewbacca. You had to have a Hans Solo, Princess Leia. You had to have Luke

Skywalker. You got to have your C3-PO, Obi-wan Kenobi. Maybe you had the Yoda. And then you

had the R2-D2. Now if you had all eight of those you had a complete set. I remember flushing

my R2-D2 down the toilet just inadvertently and it was like one of the most sad days in

my whole life. And so if you had, let's say seven of the big eight action figures, you

really wanted that last to complete your set. And so atoms are the same way. And they have

what's called the octet rule. And so what does that mean? If you're oxygen, oxygen has

six electrons. It would love to have eight so, it's got 1, 2, 3, 4, 5, 6. It would love

to have eight. And so it can share those electrons with carbon and so it can have a complete

set. In other words, the secret of life or secret of chemistry, at least half of chemistry,

is that atoms are always searching out a complete outer level. In other words the want eight

electrons in the outside level. Now likewise, carbons, since it's got four, it's got 1,

2, 3, 4, it can share those with the other oxygen. And so in carbon dioxide, they both

have eight or all three of them have eight and so they're all happy. In other words,

it's like have a complete set of action figures and you're good to go. Okay, so how do you

know which type of a bond it is? Well this will vary a little bit depending on where

you get your stats. But these numbers are pretty important to remember. If you have

somewhere between an electronegativity difference of 0.5 and 0.0, it's a non-polar covalent.

If you're electronegativity differences are between 1.7 and 0.5 then it's a polar covalent.

And if it's above 1.7 then it's an ionic. Now first thing I need to talk about then

is electronegativity. What is electronegativity? Electronegativity is a measure of how much

you want electrons. And so the more electrons you want or the more you need those electrons,

the higher you're electronegativity is. And so fluorine up here, fluorine has 7 valence

electrons. That means if it can get one more valence electron it's going to have a complete

set. In other words it almost has all of the Star Wars action figures except maybe Yoda.

If it can get that last one, then it's going to be happy. And so the highest electronegativity

of everything up here is going to be fluorine. It has an electronegativity of 3.98. And so

as we move across the periodic table those numbers get larger. Also as we go up on the

periodic table it increases as well. So who doesn't want any electrons? Well it's francium.

Francium has an electronegativity of 0.7. That means it has one valence electron and

it doesn't need to hold on to it that much. In other words it would be easy to give off

that electron. It has a complete set right underneath it. And so it's going to be really,

really happy. And so by looking at the differences between the atoms and their electronegativity

differences, we can easily figure out what kind of chemical bond we have. So let's do

some for example. Let's do water. And so you know that water is H2O. So all we do is look

up the electronegativity of the two atoms. And so here's our hydrogen right here. Here's

our oxygen. Well oxygen's electronegativity, I'm just reading it on this chart, so in my

class you'd have to use your periodic table, it has an electronegativity of 3.44. I'm going

to subtract that of hydrogen, which is 2.20. And so I get a difference of 1.24. That's

the difference in their electronegativity between these two. So what kind of bond is

that? Well I look on my chart. It's somewhere between 0.5 and 1.7. And so I know immediately

that that's going to be a polar covalent bond in water. Let's go to another one. Here's

diesel fuel. This is centane. Diesel fuel is going to be C16H34. So if I look at, it's

hard to draw there, the bond between a carbon and a hydrogen, I just find them on the periodic

table. So carbon has an electronegativity on 2.55. In other words it wants the electrons

a little less then oxygen just did. Hydrogen has an electronegativity of 2.20. And so if

I find the difference between those two I get 0.35. And so what type of bond is found

in diesel fuel? Well it's less than 0.5 and so that's going to be a non-polar covalent.

That also explains why when you have diesel fuel and you pour it into water they don't

mix. Because one of them is non-polar and the other one is polar. And only likes will

attract to likes. Okay. Let's go to the last one. That's salt. Salt, what is salt? Salt

is NaCl. If we look up our electronegativity of salt, we're going to find sodium, oops,

all the way over here so it's 0.93. I'm going to then find chlorine. Chlorine is 3.16. Three

point one six. So I subtract 3.16 minus 0.93, as I try to do that in my head, that'd be

like two point what . . . 2.23. So it doesn't matter if I got my math right. We know that

that is greater than 1.7 so we know that' going to be an ionic bond. And so when you

look at salt, these are actually chlorine ions that are attracted to sodium cations.

In other words you've actually transferred that electron from the sodium to the chlorine

and so those like charges are attracting it. If we were to do one more, this in ammonia.

And so ammonia is NH3 and so you should be able to figure this one out. So first we look

up hydrogen. Then we look up nitrogen. And so the difference is going to be 3.04 minus

2.20. And so which one is it? Is it non-polar? Is it polar covalent? Or is it ionic?