Write Lewis structures that obey the octet rule (duet rule for H) for each of the following mole

Write Lewis structures that obey the octet rule (duet rule...

Key Concepts

Lewis Structures

Lewis structures are diagrams that show the bonding between atoms of a molecule and the lone pairs of electrons that may exist. They serve as a fundamental tool in chemistry for visualizing how atoms share electrons to form molecules and for predicting the layout of electrons in various bonding scenarios.

Octet Rule

The octet rule is a guiding principle in chemistry that posits that atoms tend to form bonds in such a way that they each have eight electrons in their valence shell, mimicking the electron configuration of noble gases. This rule helps explain and predict the chemical bonding behavior of many nonmetal elements.

Duet Rule

The duet rule is a simplified version of the octet rule specifically for hydrogen, which can only accommodate two electrons in its valence shell. This rule is crucial when constructing Lewis structures, as hydrogen atoms must be shown with only two electrons, ensuring proper representation of their bonding capabilities.

Central Atom Concept

When drawing Lewis structures, the central atom is often chosen as the atom that is less electronegative or capable of forming the greatest number of bonds. Selecting an appropriate central atom helps in systematically arranging other atoms around it, facilitating the satisfaction of the octet and duet rules across the molecule.

Bonding and Nonbonding Electrons

A clear understanding of bonding and nonbonding electrons is essential when constructing Lewis structures. Bonding electrons are shared between atoms to form covalent bonds, while nonbonding electrons (lone pairs) remain localized on a single atom. Correctly allocating these electrons ensures that the overall valence electron count is preserved and that atoms achieve full valence shells as required by the octet or duet rules.

Transcript

00:02 First, let's look at the lewis structure and what this kind of means and how this kind of came about, and then understanding this octet rule.

00:10 So lewis structures are structures that we use to kind of visualize the structure of molecules.

00:16 And i'll kind of model that for you.

00:18 Let's look at, so for example, i'll write down this molecule right here, so f2.

00:25 So fluorine, two fluorines bonded together.

00:28 How would we kind of model this? and how do we show that it follows this what we call the octet rule? and kind of the steps that you want to follow when you're doing this is first, we want to look at the valence number of valence electrons.

00:41 Now, fluorine, we know it's in that column that is right before those noble gases.

00:48 And if you follow the periodic table, so for example, here's a periodic table roughly, each column will follow and we'll have one extra valence electron so for example we have hydrogen right here these runs right all these atoms all these elements that are in this column right there would have one valence electron and these are kind of just trends that we see transitional metals do not follow this that would be a little different but then you have three four five six seven clear out to the noble gas is that have a full outer shell, full eight valence electrons.

01:29 And so when we look at this, we've got to figure out, well, how many number of valence electrons.

01:33 So the first kind of rule that you want to do is you want to count how many count valence electrons in the molecules.

01:45 Okay? so we're going to do that right now.

01:47 So we have fluorine.

01:50 Floring is in the seventh row over.

01:53 And so it's got seven valence electrons.

01:57 So we have seven plus seven.

01:59 So we have 14.

02:01 So we have 14 electrons that we've kind of got to throw on here.

02:05 So we're going to draw out the lewis structure here.

02:11 So we have fluorine bonded to flooring.

02:14 And we have two electrons right there.

02:16 We need to put these rest of the 12 somewhere in there.

02:20 So we got two shared right there in that bond that i just kind of drew.

02:23 And i kind of jumped the gun.

02:25 You don't need to put that right there yet, but you would want to.

02:28 So the first thing you'll want to do is i just kind of do this.

02:31 So one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve.

02:38 Okay.

02:39 What we want is we want these electrons that they will be shared most of the time in an equal fashion.

02:45 And we want them to each have eight electrons in its outer shell.

02:50 Okay.

02:50 So if we count, we have one, two, three, four, five, six.

02:53 And then these are shared, so 7, 8.

02:56 So we got eight electrons right there.

02:58 1, 2, 3, 4, 5, 6, 7, 8.

03:00 So according to this one, so f2, it is now meeting the loose structure and the octet rule.

03:09 You don't really want, it's not going to make extra bonds.

03:12 These would just be floating, be free bonding electrons to be bonded elsewhere.

03:17 So you could have this bond to hydrogen and have a shared bond there or whatever.

03:21 Okay.

03:22 And so that's what you'll kind of see in this instance.

03:25 But we see that they each have eight electrons.

03:28 Therefore, it is meeting that requirement, and it's meeting that octet rule.

03:34 So if we go back here to our kind of our role, our steps.

03:39 So we counted the valence electrons, and then we would draw out the lewis structure and fill in the electrons.

03:56 So those are kind of the steps that i follow when i'm doing this.

04:02 Let's look at another one.

04:05 So i'm going to erase this.

04:16 All right.

04:17 So let's look at another one.

04:18 Let's look at oxygen.

04:21 So o2.

04:24 When we have o2, we're going to just follow these steps.

04:27 I draw it out.

04:28 I'm going to count how many electrons there are.

04:30 So we have two oxygens.

04:31 Now oxygen is found in the sixth column over.

04:37 And so it's going to have six.

04:40 H, six valence electrons in its outer shell.

04:44 So we have a total of 12.

04:46 Now, i'm drawing one, so we have 10 left over.

04:50 So we're going to try and figure out where do these 10 go? so we got one, two, three, four, five, six, seven, eight, nine, ten, and twelve.

05:00 Uh -oh, we have too many, right? so it doesn't really follow that.

05:04 And so we're just going.

05:06 So let's start, let's figure out, okay, what's going to happen here so we can make this work.

05:15 So we have two right there.

05:17 We have one, two, three, four, five, six, seven, eight.

05:22 So one, two, three, four, five, six, seven, eight, nine, ten.

05:25 We have two more that we need to make up, right? so we have four in right there and then one, two that are shared.

05:33 And so one thing we could do is we could have a double bond right there.

05:36 So we have one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve.

05:39 So now if we counted this, let's see if they both share eight electrons.

05:44 So we have one, two, three, four, five, six, seven, eight.

05:46 We're good.

05:47 One, two, three, four, five, six, seven, eight electrons.

05:51 And so now we know that oxygen will be double bonded to each other, and that will form the lewis structure for o2.

06:00 Let's look at another one.

06:01 Let's do it in blue.

06:04 So let's look at co.

06:06 This one's a really fun one.

06:07 Carbon monoxide.

06:09 The odorless gas, odorless poison.

06:14 And so this carbon dioxide is one of those gases that you'd most likely have a carbon monoxide detector in your home.

06:24 If you're burning natural gas or wood stove or coal or whatever, this is a byproduct of that.

06:31 And it can be very dangerous at high concentrations.

06:34 If you fall asleep and it's in the air at high concentrations, you will never wake up again.

06:40 You'll just die.

06:41 A lot of people, you know, there's some skin.

06:44 Situations of that...

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