Atomic Bonds - Chemistry Basics Part II

Summary

In this episode of the Penguin Prof channel, the focus is on chemical bonds, explaining why atoms form them and the different types, including ionic, covalent, and hydrogen bonds. The video clarifies how atoms strive for the stability of noble gases by filling their valence shells, either through gaining or losing electrons (ionic bonds) or sharing them (covalent bonds). It also highlights the importance of polarity in covalent bonds and the role of hydrogen bonds in biology, including DNA and protein structures, emphasizing their significance in various biological processes.

Takeaways

• 🌐 The script discusses various types of chemical bonds, emphasizing the importance of achieving a stable electron configuration similar to noble gases.
• 🔬 Noble gases are inherently stable due to their full valence electron shells, which is the goal for other elements to achieve through bonding.
• 🤝 The periodic table is a crucial tool for understanding the valence electrons of elements, which aids in predicting their bonding behavior.
• 💥 Ionic bonds occur when one atom donates electrons to another, resulting in the formation of positively charged cations and negatively charged anions that are attracted to each other.
• 🧠 The classic example of ionic bonding is the formation of table salt (sodium chloride) from sodium and chlorine, illustrating the transfer of electrons for stability.
• 🔄 Covalent bonds involve the sharing of electrons between atoms, with the possibility of equal or unequal sharing leading to nonpolar or polar covalent bonds, respectively.
• 🌀 Polar covalent bonds, such as in hydrogen fluoride, occur when there is an unequal distribution of electron density, resulting in partial positive and negative charges within the molecule.
• 💧 Water is a prime example of a polar molecule due to the polar covalent bonds between oxygen and hydrogen, which gives water its unique properties.
• ❄️ Hydrogen bonds are weak interactions between polar molecules, exemplified by the slight negative and positive ends of water molecules, which contribute to water's exceptional characteristics.
• 🧬 Hydrogen bonds play a significant role in biological systems, including the structure of DNA, the shape of proteins, and the binding of enzymes and antibodies.
• 📚 The script encourages viewers to revisit part one for foundational knowledge and to utilize the periodic table as a guide to understanding atomic structure and bonding.

Q & A

What is the main topic of the video?

The main topic of the video is about chemical bonds, including why atoms form them, the different types of bonds, and the role of valence electrons in achieving stability similar to that of noble gases.

What does the video suggest is the key to an atom's 'happiness'?

The key to an atom's 'happiness' is having a full valence shell, which provides a stable electron configuration similar to that of noble gases.

Why are noble gases considered 'happy'?

Noble gases are considered 'happy' because their valence shells are already full, giving them a stable electron configuration without the need to form bonds with other atoms.

What is an ionic bond and how is it formed?

An ionic bond is formed when one atom donates one or more electrons, becoming a positively charged ion (cation), and another atom accepts those electrons, becoming a negatively charged ion (anion). The bond is due to the attractive force between these oppositely charged ions.

What is the role of the periodic table in understanding chemical bonds?

The periodic table helps in understanding chemical bonds by indicating the number of valence electrons an element has, which is crucial in determining the type of bonding it will participate in to achieve a stable electron configuration.

How does the process of ionic bonding result in the formation of table salt?

Ionic bonding results in the formation of table salt when sodium, which loses one electron to achieve a stable configuration, bonds with chlorine, which gains one electron to complete its valence shell, forming a stable ionic compound (NaCl).

What is a covalent bond and how does it differ from an ionic bond?

A covalent bond is a type of chemical bond where atoms share one or more pairs of electrons. It differs from an ionic bond, which involves the transfer of electrons from one atom to another, resulting in ions with opposite charges that are attracted to each other.

What is a polar covalent bond and how does it form?

A polar covalent bond forms when two atoms share electrons, but one atom exerts a stronger pull on the shared electrons due to its higher electronegativity, resulting in an uneven distribution of electron density and creating a molecule with distinct positive and negative poles.

Why are hydrogen bonds important in biology?

Hydrogen bonds are important in biology because they contribute to the structure and function of many biological molecules, such as DNA and proteins, and are responsible for properties of water that are essential for life, including its high heat capacity and the fact that ice floats.

What is the significance of hydrogen bonds in the properties of water?

Hydrogen bonds are significant in the properties of water because they give water its high heat capacity, high surface tension, and the unique property of ice being less dense than liquid water, which allows ice to float.

How do hydrogen bonds contribute to the structure of DNA?

Hydrogen bonds contribute to the structure of DNA by holding the two strands of the double helix together. The weak bonds between the nitrogenous bases allow the DNA to unzip for replication and then re-zip to maintain its structure.

Why are covalent bonds sometimes polar and sometimes nonpolar?

Covalent bonds are polar when there is an unequal sharing of electrons due to a difference in electronegativity between the atoms, while they are nonpolar when the sharing is equal and both atoms have similar electronegativities.

Outlines

00:00

🔬 Atomic Bonding and the Quest for Stability

The script introduces the concept of atomic bonding, explaining why atoms form bonds and the different types of bonds that exist. It emphasizes the importance of understanding elements, the periodic table, and atomic structure, particularly the role of electrons in bonding. The video aims to clarify why noble gases are stable due to their full valence shells and how other elements strive to achieve similar stability through bonding. The periodic table is highlighted as a crucial tool for understanding valence electrons and predicting bonding behavior. The script also previews the topics of ionic, covalent, and hydrogen bonds, and their significance in various chemical and biological processes.

05:01

💥 Ionic Bonds: The Transfer of Electrons

This section delves into ionic bonding, where electrons are transferred rather than shared. It describes how one atom donates electrons to become a positively charged cation, while another atom accepts electrons to become a negatively charged anion. The electrostatic attraction between these oppositely charged ions forms the ionic bond. The script uses the example of sodium and chlorine forming table salt to illustrate this process, showing how both atoms achieve a stable electron configuration similar to noble gases. Additionally, the concept of electron affinity and the periodic table's role in predicting ionic bonding is discussed, along with the formation of calcium chloride as another example of ionic bonding.

10:02

🤝 Covalent Bonds: Sharing for Stability

The script explains covalent bonds, where electrons are shared between atoms to achieve stability. It distinguishes between nonpolar covalent bonds, where electrons are shared equally, and polar covalent bonds, where sharing is unequal due to differences in electronegativity. Examples of covalent bonds include hydrogen gas with a single bond, carbon dioxide with double bonds, and nitrogen gas with a triple bond. The script also introduces the concept of electronegativity and how it varies across the periodic table, affecting the polarity of covalent bonds. The use of molecular diagrams to represent these bonds is highlighted, along with the significance of covalent bonding in biological systems.

🌐 Polarity and Hydrogen Bonding in Biology

This part of the script discusses the concept of polarity in more detail, using hydrogen fluoride and water as examples of polar covalent bonds. It explains how the unequal sharing of electrons results in regions of partial positive and negative charges within molecules. The script then introduces hydrogen bonds as weak interactions between these partial charges, crucial for the unique properties of water and its biological importance. Hydrogen bonds are shown to be responsible for water's high heat capacity, its anomalous density as ice, and their role in the structure of DNA, proteins, and in enzymatic and immunological processes. The script concludes by emphasizing the pervasive influence of hydrogen bonding in biological systems.

Keywords

💡Chemical Bonding

Chemical bonding refers to the process by which atoms form stable structures by sharing or transferring electrons. In the video, this concept is central to understanding why atoms form bonds and the types of bonds that can occur, such as ionic and covalent bonds. The script uses the idea of atoms seeking stability akin to noble gases to explain the motivation behind chemical bonding.

💡Valence Electrons

Valence electrons are the outermost electrons of an atom that are involved in chemical bonding. The script emphasizes their importance in determining how atoms interact with each other to achieve a stable electron configuration, often by sharing or transferring these electrons to fill their outermost shell.

💡Noble Gases

Noble gases, such as helium, neon, and argon, are a group of chemical elements in Group 18 of the periodic table. They are characterized by having full valence electron shells, which makes them stable and unreactive. The video uses noble gases as a reference point for the stability that other atoms seek through bonding.

💡Ionic Bond

An ionic bond is a type of chemical bond formed through the electrostatic attraction between oppositely charged ions, typically resulting from the transfer of one or more electrons from one atom to another. The script illustrates this with the example of sodium (which donates an electron) and chlorine (which accepts an electron), forming a stable compound like table salt.

💡Covalent Bond

A covalent bond involves the sharing of electron pairs between atoms. The video explains that covalent bonds can be either nonpolar, where the sharing is equal, or polar, where one atom exerts a stronger pull on the shared electrons. Examples from the script include hydrogen gas with a single bond and carbon dioxide with a double bond.

💡Polarity

Polarity in chemistry refers to the distribution of electrical charge across a molecule, resulting in regions of higher negative and positive charge. The script explains how polarity arises in polar covalent bonds, such as in hydrogen fluoride, where fluorine's stronger attraction for electrons creates a dipole across the molecule.

💡Hydrogen Bond

A hydrogen bond is a weak chemical interaction that occurs between a hydrogen atom covalently bonded to a highly electronegative atom (like oxygen or nitrogen) and another electronegative atom. The video highlights the significance of hydrogen bonds in biology, such as holding DNA together and contributing to the unique properties of water.

💡Electron Affinity

Electron affinity is the measure of the tendency of an atom to attract additional electrons. The script uses this concept to explain the formation of polar covalent bonds, noting that atoms like fluorine have a high electron affinity, leading to an unequal sharing of electrons in bonds.

💡Periodic Table

The periodic table is a tabular arrangement of chemical elements, ordered by their atomic number, electron configuration, and recurring chemical properties. The script emphasizes its importance in predicting the valence electrons and the types of bonds elements are likely to form.

💡Stability

In the context of the video, stability refers to an atom's electron configuration that resembles that of noble gases, which have full valence electron shells. Achieving this stable state is the driving force behind atoms forming bonds with each other, as illustrated by the formation of ionic and covalent bonds.

💡Double and Triple Bonds

Double and triple bonds are types of covalent bonds where two or three pairs of electrons, respectively, are shared between atoms. The script uses carbon dioxide and nitrogen gas as examples, where carbon shares two pairs of electrons with each oxygen atom in a double bond, and two nitrogen atoms share three pairs in a triple bond, achieving stability.

Highlights

Introduction to the concept of bonds in chemistry and their importance for achieving stability like noble gases.

Explanation of why noble gases are stable due to their full valence shells and why other atoms form bonds.

The role of the periodic table in understanding valence electrons and predicting bonding behavior.

Introduction to ionic bonds as a result of electron transfer creating oppositely charged ions that attract each other.

The classic example of ionic bonding between sodium and chlorine to form stable salt.

Explanation of how calcium chloride is formed through the ionic bonding of calcium with two chloride ions.

Introduction to covalent bonds as a result of electron sharing between atoms.

Discussion on the difference between nonpolar and polar covalent bonds based on the equal or unequal sharing of electrons.

Use of the periodic table to predict the polarity of bonds based on electron affinity.

Illustration of hydrogen gas forming a nonpolar covalent bond by sharing one pair of electrons.

Explanation of how carbon dioxide forms stable molecules through double covalent bonds with oxygen.

Description of oxygen gas forming a stable molecule with a double bond between two oxygen atoms.

Introduction to nitrogen gas and its triple bond as an example of a stable covalent bond.

Explanation of polar covalent bonds, using hydrogen fluoride as an example where fluorine pulls electrons more strongly.

Introduction to the concept of polarity in molecules and its significance in biological structures.

Explanation of hydrogen bonds as weak interactions between slightly positive and negative regions in molecules.

Importance of hydrogen bonds in the properties of water, such as high heat capacity and the floating of ice.

Role of hydrogen bonds in biological processes like DNA structure, protein folding, and enzyme-substrate interactions.

Conclusion emphasizing the importance of understanding chemical bonds in various biological contexts.

Transcripts

>> Hello. And welcome to the Penguin Prof channel.

In today's episode, I want to continue

to my basic chemistry concepts.

We're going to be talking about bonds, all kinds of bonds.

Why atoms form them, what kinds of bonds are possible,

and some more good stuff.

I want to make sure everybody watched part one.

Did you watch part one?

Part one was really about elements, the periodic table,

understanding atomic structure

and why it's all about the electrons.

If you haven't seen it, or you're unfamiliar

with those topics, check it out.

Otherwise, this can be a little bit daunting, I know.

It can make your head spin

or in my case it can make your Penguin spin.

We're going to try and make some sense of it.

We're going to look at why the noble gases are actually

so happy.

We looked at that before, but we're going to explore

in this video how all the other atoms try and become

as happy as the noble gases.

The noble gases, if you recall,

they are happy their valence shells are full.

That is to say, everyone is trying to attain this level

of stability that the noble gases have all by themselves.

So, this is why they don't play well with others.

But everybody else on the periodic table has to bond

with other atoms to try to attain that level of stability.

So, unless you're noble gas,

at the key to becoming happy is atomic bonding, and that's kind

of where we left it last time,

and this is the topic we're going to explore today.

The key to happiness is a full valent shell.

Right. And of course, you want to feel just

like a noble gas even if you're not.

So, if you recall, the periodic table and the valence electrons,

it's pretty easy because all you have to do is look straight

down in these groups or the columns,

and you see how many valence electrons a particular element

will have that's going to make it a lot easier.

So, the periodic table is your friend, whether you want it

to be or not, it's going to simplify your life.

Trust me on this.

We're going to look at different ways that atoms play together,

ionically, covalently, and we're going to look at hydrogen bonds.

And they're actually very important in biology

because they hold a lot of really important stuff together.

The first bond we're going to look

at is the ionic bond, taken, not shared.

So dramatic.

In ionic bonding, what's going to happen is one atom is going

to donate one or more electrons, and when that happens,

it's going to gain a positive charge.

We're going to see why.

Meanwhile, another atom is going to receive one

or more electrons, and it's going to gain a negative charge.

Now, here's the key.

In chemistry, opposites attract.

So, it is the attractive force

between the positively charged ion and the negative charged ion

that holds the whole thing together.

That's the bond.

So, in their elemental state, that is when you look

at the periodic table, the atoms are all neutral.

Now, if an atom loses electrons, one or more, it becomes an ion,

which means that it has an electric charge.

And specifically, it becomes a cation,

that is a positively charged ion.

On the other hand, some atoms will gain one or more electrons.

They also become ions, but they will gain a negative charge,

and we use the term anion to represent that.

If you've worked with batteries, of course,

you're familiar with these.

Cathodes, anodes, all the same thing.

So, the key is that these opposite charges attract

each other.

That's where the bond is.

So, let's look at the classic example of the ionic bond.

You know, textbooks act

as if there is only one example, but we'll look at it.

Sodium and chlorine, you notice they're at opposite ends

of the periodic table.

What we've got here is a scenario where sodium,

remember the electrons fill from the inside out,

and it's got a valent shell of one electron, one lone electron.

This is not a happy situation.

Meanwhile, chlorine has seven valence electrons

and would like to have eight.

It would like to feel like a noble gas.

So, it is also very unhappy, but when sodium

and chlorine get together,

something really cool can happen.

Sodium can lose that one electron.

Look what happens now.

Now its second shell, the shell right here, is full.

So, sodium is happy.

Meanwhile, chlorine gains an extra electron.

It then has a full valent shell also, so it becomes happy.

Everybody is happy.

Now, the thing is, don't forget though,

that sodium now has one less electron than it has protons,

while chlorine has one extra electron,

compared to the number of protons.

That's where those charges come into play.

So, now you notice that this is not an atom anymore.

It's an ion.

It has a charge.

Specifically, it's a cation.

Chlorine is also an ion, specifically it's an anion,

it is the attraction between these two opposite charges

that holds sodium and chloride together.

And you make salt.

I know, it's just incredible how you make salt.

So exciting.

It's extremely stable because sodium and chloride really

like to hang out together.

And you can see why.

Opposites attract.

If you look at another example, calcium chloride,

now if you recall, this group has two valence electrons,

and of course chlorine still has seven.

So, you might already start to think hmm,

if calcium has two electrons in its valent shell,

and it could get rid of those,

that would also make it stable and happy.

So, all you got to do in that case is bind with not one

but two chloride ions in order to achieve that stability.

So, calcium gives up its two outermost electrons,

one to this chloride ion and one to this chloride ion.

And the whole thing is held together

in a very stable configuration.

That's calcium chloride.

So, sometimes electrons are not taken but rather shared.

When that happens, we refer to the sharing

of electrons as a covalent bond.

But immediately, you might start to think, you know,

is sharing always equal?

Well, in humans, certainly sometimes it is,

and sometimes it's not.

The same thing is true for atoms.

So, sometimes the atoms exert equal pulls on the electron,

and we refer to that kind of a bond

as a nonpolar covalent bond.

We'll see why in a little bit.

Sometimes, one atom has a stronger pull.

It wants the electrons more than the other, so it kind of,

the electrons will kind of play favorites because one atom is

so much more desirable than another.

How do you know who wants the electron more?

How can you predict that?

I mean how would you ever know such a thing?

Oh, my God, it's on the periodic table.

It turns out that as you go across from left to right

and as you go up, you have increasing electron affinity.

That means how much any given atom wants electrons,

they want electrons so badly the more you go towards this corner.

Remember, excluding the noble gases,

because they're already happy already.

So, who is at the top right corner?

Oh, my gosh, it's fluorine.

Fluorine is the most electron-desiring atom

in the whole periodic table, and if you know that,

then this joke is actually function.

Okay. Very geeky.

So, let's look at some covalent bonds, and we're going to look

at the first one, hydrogen gas, which I actually showed you

in the first video in my chemistry concepts series.

Hydrogen is the smallest atom.

It has one electron in its valent shell,

would like to have two.

So, one thing that hydrogen can do is get together

with another hydrogen atom and share electrons.

So, each one shares the one electron that is has.

This is a typical way that we draw it,

and when you see this little line, this means one pair

of electrons being shared.

Okay, so that's what those lines mean.

You're going to see that all over the place.

Now, it turns out you can share more than one pair,

so you can have a single, as we just saw, but also a double

or even a triple bond.

Oh, I love gelato, don't you love gelato.

This is reason to go to Italy.

If you go, make sure that you look for this word,

[foreign language spoken],

which means that it's actually hand made.

If you're going to eat gelato, that's the only way to go.

Sorry, back to covalent bonds.

We're going to look at carbon dioxide.

So, carbon, you recall, has four electrons in its valent shell.

Oxygen has six.

So, in order for this molecule to be stable,

you need to share more than one pair of electrons

between the carbon and each of the two oxygens.

So, this means that we these two lines right here,

that represents two pairs of electrons being shared,

and these two lines here represent two pairs

of electrons being shared.

And now, if you count up all the electrons

around each atom, everybody is happy.

They all have eight electrons in their valent shell.

What about oxygen gas,

oxygen has six electrons in its valent shell.

So, if two oxygen atoms come together in order for them

to have the full octet, they also need to form a double bond.

And now, if you count around, for each of the oxygens,

this line represents two, this line represents two for four,

then you have five, six, seven, eight.

Same thing for this guy.

So, everybody is happy.

Okay, let's look at one more.

How about nitrogen gas?

Now, nitrogen has five valence electrons.

So, for nitrogen to form covalent bonds

with another nitrogen, they need to share three pairs.

So, two nitrogens will come together and form a triple bond.

So, covalent bonds represent sharing of electrons,

and so far all of this sharing that we have looked at is equal.

These are nonpolar covalent bonds.

What if the sharing is unequal?

We've got to talk about this term polarity,

and hopefully the term polarity makes you think about dualism

or something where there are two sides that are different.

In biology, if you think about mitosis, and you know

about the opposite poles of a cell as it prepares

to divide, that could help.

Most people know about the poles on the globe.

Of course, we have the North Pole with polar bears,

and we have the South Pole with penguins on it.

That's a pretty good example.

Now, if you didn't know that and you thought there were penguins

at the North Pole, don't feel bad.

It's not your fault.

It's because Hallmark puts penguins on the Christmas cards

and with Santa it drives me crazy.

Okay. Let's look at a situation

where electrons are not shared equally,

as in the case of hydrogen fluoride.

Remember, fluorine wants electrons more than anybody else

on the periodic table.

So, let's look at hydrogen and fluorine as they come together.

Hydrogen has one valence electron.

Fluorine, of course, has seven, and when they come together,

so this is fluorine and this is hydrogen,

and this diagram is supposed to represent the fact

that fluorine has such a great pole on the electrons

that the redder color represents the more negative side,

and the blue represents the more positive side of this thing.

Now, these are not electrical charges.

This is not an ion.

This is still a covalent bond, but it's polar.

So, it means that one side of the molecule is more negative.

The other side of the molecule is more positive.

So, we call this a polar covalent bond.

Another classic example of polar covalent bonds, water.

Here's the oxygen, and these are the two hydrogens,

and the oxygen exerts a much greater electron pull

than the hydrogens.

So, the electrons prefer to hang out more on this end,

so it makes this end, the oxygen end, slightly negative.

The hydrogen end is slightly positive.

And that's why water is polar.

I turns out that hydrogen bonds are kind of related to this.

Hydrogen bonds are weak interactions

between slight negatives and slight positives.

Even if it's slight, opposites still attract,

and it's actually hydrogen bonds that account

for all the amazing properties of water.

The fact that water holds so much heat,

it has a high vaporization.

The fact that ice floats.

I mean, you probably don't think

about this too much unless you are a penguin,

but it's something that other substances don't do, right.

The solids are always more dense than the liquids, so this is all

because of hydrogen bonding.

So, hydrogen bonds are actually really important.

So, let's look at water a little bit.

You know, the more I look at it, I think water looks just

like Mickey Mouse, doesn't it?

I mean, maybe that's just mean.

I mean, if we orient the Mickey Mouse heads,

wait a min, sorry, squirrel.

Okay, let's go back.

If you look at this, on the oxygen end,

this end represents a slight negative end.

This end, it's not shown here, this is slightly positive,

but it's shown here, this slight negative

and the slight positive, they attract each other.

That, the dash lined, that's the hydrogen bond.

And here's another one,

and here's another one, here's another one.

These are the hydrogen bonds between water that are

so important and give rise to all of its amazing properties.

Hydrogen bonds are important in other areas too.

Hydrogen bonds actually hold DNA together.

That might surprise you, because they're actually fairly

weak bonds.

But, it turns out that's really important because DNA has

to unzip and open up in order

to do all the things it needs to do.

Hydrogen bonds also gives rise to a lot

of the structural features we see in proteins

like an alpha helix and a beta sheet, and in addition to that,

oh, my gosh, so much more.

Enzymes bind to substrates because of hydrogen bonds,

and antibodies bind to antigens because of hydrogen bonds,

and it goes on and on and on.

Hydrogen bonds turn out to be really important in biology,

and you're going to see that as you continue in your studies.

As always, I thank you

for visiting the Penguin Prof channel.

I hope this was helpful.

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Good luck.