Lewis Diagrams Made Easy: How to Draw Lewis Dot Structures

Summary

In the video 'Lewis Diagrams Made Easy with Ketzbook,' viewers are guided through the process of drawing Lewis diagrams for atoms and simple molecules. The tutorial begins with determining valence electrons, using chlorine as an example, and progresses to constructing diagrams for elements like hydrogen, carbon, and oxygen. The video explains covalent bonding and how atoms share electrons to achieve a stable electron configuration. It then demonstrates how to draw Lewis diagrams for molecules like H2O and SO3, emphasizing the importance of satisfying the octet rule for non-metals and duet for hydrogen. The steps include counting valence electrons, identifying the central atom, forming bonds, distributing remaining electrons, and adjusting for a full octet or duet. The tutorial is designed to make understanding and creating Lewis diagrams accessible and straightforward.

Takeaways

• 🔍 Chlorine (Cl) has 7 valence electrons, which is determined by its position in the 7th column of the Periodic Table.
• 📐 Lewis diagrams represent valence electrons with dots, arranged in a square around the element symbol with no more than two dots on any side.
• 💡 Non-metal elements aim for a full octet (8 valence electrons), while hydrogen seeks a duet (2 valence electrons).
• 🔗 Covalent bonding in molecules involves sharing electrons to achieve the desired electron count, represented by lines in Lewis diagrams.
• 👫 In H2, two hydrogen atoms share their single electrons to satisfy the duet rule for both.
• 🔵 A double bond in a molecule like O2 represents the sharing of 4 electrons, resulting in each atom having 8 valence electrons.
• 🔴 Triple bonds, as seen in N2, involve the sharing of 6 electrons, also leading to an octet for each nitrogen atom.
• 💧 To draw a Lewis diagram for a molecule like H2O, follow five steps: count valence electrons, determine the central atom, draw single bonds, place remaining electrons as lone pairs, and adjust to achieve octets or duets.
• 🔄 For molecules like SO3, adjust lone pairs to double bonds if necessary to ensure all atoms have a complete octet, making the sulfur atom 'happy' with 8 valence electrons.
• 📝 Practice is key when learning to draw Lewis diagrams, ensuring you can correctly represent the valence electrons and bonding in molecules and ions.

Q & A

How many valence electrons does chlorine have?

Chlorine has 7 valence electrons, as indicated by its position in the 7th column of the Periodic Table.

How do you represent valence electrons in a Lewis diagram?

Valence electrons are represented by dots in a Lewis diagram, with no more than two dots on any side of an imaginary square drawn around the element's symbol.

What is the significance of the imaginary square when drawing Lewis diagrams?

The imaginary square is used as a guide to neatly arrange the dots representing valence electrons around the element's symbol, ensuring no side has more than two dots.

Why do atoms share electrons in covalent bonding?

Atoms share electrons in covalent bonding to achieve a full octet or duet, which means having 8 valence electrons for non-metals, except for hydrogen which wants 2.

How is the hydrogen molecule represented in a Lewis diagram?

The hydrogen molecule (H2) is represented by a single line between the two hydrogen atoms, indicating a single bond and two shared electrons.

What is the difference between a lone pair and a bonding pair in a Lewis diagram?

A lone pair consists of two dots representing non-bonding electrons, while a bonding pair is represented by a line between atoms, indicating shared electrons.

How do you determine the central atom in a molecule for Lewis diagram drawing?

The central atom is usually the one that is bonded to all other atoms and is often the element that appears only once in the molecular formula.

What is the first step in drawing the Lewis diagram for a molecule?

The first step is to count all of the valence electrons in the molecule by adding up the valence electrons of each atom present.

How do you distribute the remaining valence electrons after forming single bonds in a Lewis diagram?

The remaining valence electrons are distributed as lone pairs on the atoms, starting with the central atom and following the octet rule, except for hydrogen which is satisfied with a duet.

What should you do if an atom does not have an octet after placing lone pairs in a Lewis diagram?

If an atom does not have an octet, you can convert some lone pairs into additional bonds with other atoms to achieve the octet or duet, as seen in the example of sulfur trioxide where a double bond is formed between sulfur and oxygen.

Outlines

00:00

🔬 Introduction to Drawing Lewis Diagrams

This section introduces viewers to the basics of drawing Lewis diagrams, which are used to represent the valence electrons in atoms and simple molecules. The script begins with a question about the number of valence electrons in chlorine, which is answered by referring to the periodic table. It explains that elements in the same column have the same number of valence electrons, with the exception of helium. The script then demonstrates how to draw the Lewis diagram for chlorine, emphasizing the correct placement of dots around the element symbol. It also covers the Lewis diagrams for hydrogen, carbon, and oxygen, and explains how to represent covalent bonds using lines and dots. The importance of satisfying the octet or duet rule for non-metal elements, except hydrogen, is highlighted. The script also explains how to draw Lewis diagrams for molecules like H2, which involves sharing electrons to achieve a full valence shell.

05:05

📚 Steps for Drawing Lewis Diagrams of Molecules

This section provides a step-by-step guide on how to draw Lewis diagrams for molecules, using water (H2O) and sulfur trioxide (SO3) as examples. The first step is to count all valence electrons in the molecule. For water, this includes two from hydrogen and six from oxygen, totaling eight electrons. The central atom, usually the one present in the smallest quantity, is identified next; for water, this is oxygen. Single bonds are then drawn to the central atom, followed by the placement of remaining valence electrons as lone pairs. The script emphasizes not to exceed two valence electrons for hydrogen. The final step involves converting lone pairs into double or triple bonds to achieve an octet for all atoms, except hydrogen, which only needs a duet. The script also highlights the importance of checking that all atoms have achieved their required electron configuration. The example of sulfur trioxide illustrates how to adjust lone pairs into double bonds to satisfy the octet rule for all atoms in the molecule.

Keywords

💡Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom, which are involved in chemical reactions and bonding. In the context of the video, understanding the number of valence electrons is crucial for drawing Lewis diagrams, as these diagrams represent the valence electrons of atoms and how they are shared or arranged in molecules. For example, chlorine has 7 valence electrons, which is indicated by the chlorine symbol 'Cl' surrounded by 7 dots in its Lewis diagram.

💡Periodic Table

The Periodic Table is a tabular arrangement of chemical elements, organized by atomic number, electron configuration, and recurring chemical properties. The video script uses the Periodic Table to determine the number of valence electrons for elements like chlorine, which is found in the 7th column, indicating it has 7 valence electrons. The table is a fundamental tool in chemistry for predicting how elements will behave in chemical reactions.

💡Lewis Diagrams

Lewis Diagrams, also known as electron dot diagrams, are visual representations of the valence electrons of atoms and how they are shared in chemical bonds. The video's main theme revolves around teaching how to draw these diagrams for atoms and simple molecules. Lewis diagrams are essential for understanding covalent bonding, where atoms share electrons to achieve a stable electron configuration.

💡Covalent Bonding

Covalent bonding is a type of chemical bond formed between atoms by the sharing of electron pairs. The video explains that in covalent bonds, atoms aim to achieve a full octet (8 electrons) or a duet (2 electrons for hydrogen) of valence electrons. This concept is demonstrated through the Lewis diagrams of molecules like H2, where two hydrogen atoms share their single electrons to satisfy the duet rule.

💡Octet Rule

The Octet Rule states that atoms are most stable when they have eight electrons in their valence shell. The video emphasizes the importance of the octet rule in drawing Lewis diagrams, as atoms form bonds to achieve this stable configuration. For instance, in water (H2O), the oxygen atom forms two single bonds with hydrogen atoms and has two lone pairs, resulting in a total of 8 electrons around the oxygen.

💡Central Atom

In a molecule, the central atom is the one that is bonded to all other atoms. The video describes how to determine the central atom in a molecule, usually the one that is present in the smallest quantity or is typically more electronegative. For example, in water (H2O), oxygen is the central atom because it is bonded to two hydrogen atoms.

💡Lone Pairs

A lone pair of electrons refers to a pair of electrons that are not involved in bonding and remain on an atom. The video explains that in Lewis diagrams, lone pairs are represented by two dots. In the case of oxygen in a water molecule, it has two lone pairs, in addition to the electrons involved in bonding with hydrogen atoms.

💡Single, Double, and Triple Bonds

These terms refer to the number of electron pairs shared between two atoms in a covalent bond. A single bond involves one pair of electrons, a double bond involves two pairs, and a triple bond involves three pairs. The video uses the example of a hydrogen molecule (H2) with a single bond and an oxygen molecule (O2) with a double bond to illustrate these concepts.

💡Molecular Geometry

Molecular geometry is the three-dimensional arrangement of atoms within a molecule. While the video does not explicitly discuss molecular geometry, the placement of electrons in Lewis diagrams can imply certain geometries. For example, the Lewis diagram of water (H2O) suggests a bent or V-shaped molecular geometry due to the arrangement of the two lone pairs and the two bonding pairs on the oxygen atom.

💡Steps for Drawing Lewis Diagrams

The video outlines a step-by-step process for drawing Lewis diagrams, which includes counting valence electrons, determining the central atom, drawing single bonds, placing remaining electrons as lone pairs, and adjusting lone pairs to form additional bonds if necessary. This structured approach is crucial for accurately representing the electron distribution in molecules and ensuring that all atoms achieve a stable electron configuration.

Highlights

Introduction to drawing Lewis Diagrams for atoms and simple molecules.

Question posed: How many valence electrons does chlorine have?

Explanation of how to determine valence electrons from the Periodic Table.

Chlorine's position in the Periodic Table indicates it has 7 valence electrons.

Lewis diagrams use dots to represent valence electrons.

Proper placement of dots around the element's symbol in a Lewis diagram.

Lewis diagrams represent covalent bonding in molecules and ions.

Non-metal elements seek 8 valence electrons, except hydrogen which seeks 2.

Example of a simple molecule: Hydrogen (H2) and its Lewis diagram.

Shared electrons in covalent bonding are counted as owned by both atoms.

Representation of shared electrons with lines and non-bonding electrons with dots.

Example of a molecule with a double bond: Oxygen (O2).

Example of a molecule with a triple bond: Nitrogen (N2).

Steps to draw the Lewis diagram of a molecule, starting with water (H2O).

Counting all valence electrons in a molecule is the first step in drawing its Lewis diagram.

Determining the central atom in a molecule.

Drawing single bonds to the central atom in a Lewis diagram.

Placing remaining valence electrons as lone pairs on atoms.

Ensuring every atom has an octet or duet by adjusting lone pairs to bonds.

Final check to ensure all atoms in the Lewis diagram are satisfied.

Additional example: Drawing the Lewis diagram of sulfur trioxide (SO3).

Adjusting lone pairs to double bonds to achieve octets for all atoms.

Encouragement to follow the steps when drawing Lewis diagrams.

Transcripts

Welcome to Lewis Diagrams Made Easy with Ketzbook

Today we are going to learn how to draw Lewis Diagrams for atoms and simple molecules,

but before we begin, let's start with a question.

How many valence electrons does chlorine have?

In order to answer that question, we need to look at the Periodic Table.

Remember that within any given column, all the elements have the same number of valence electrons.

To get that number, all we do is count the columns starting from the left.

Skip the transition metals, and remember that the only exception to this is helium,

which has only 2 valence electrons, not 8.

Now, find chlorine in the Periodic Table.

Remember that it's symbol is Cl.

See it in the 7th column?

That tells us that it has 7 valence electrons.

Knowing the number of valence electrons an element has is critical, and in Lewis diagrams,

we use dots to represent valence electrons.

So, the Lewis diagram of chlorine is the symbol Cl with 7 dots around it.

When you draw the dots, don't just put them anywhere.

Instead, imagine a square around the element's symbol.

The dots should be neatly drawn on the four sides of the square with no more than two

dots on any side.

Practice drawing the Lewis diagrams of a few elements just to make sure you've got it.

This is the Lewis diagram of hydrogen, which has only one valence electron.

This is carbon, which has four valence electrons, and this is oxygen, which has 6 valence electrons.

Where you put the dots doesn't really matter as long as you neatly draw them along the

sides of an imaginary square and never put more than two dots on one side.

Lewis diagrams are often used to represent covalent bonding in molecules and ions.

In covalent bonding, atoms share valence electrons in order to get a full octet or duet,

that is every non-metal element wants 8 valence electrons,

except for hydrogen, which only wants two valence electrons.

The simplest molecule possible is that of hydrogen, H2.

A hydrogen atom has one valence electron, but it wants to have two.

So, in order to satisfy its desire for another electron,

two hydrogen atoms will share their electrons with each other.

And the crazy thing is that in the wonderful world of atoms,

the shared electrons are counted as owned by both atoms.

That means that both hydrogen atoms are happy because they both satisfy the octet rule.

Now, we normally draw hydrogen and other molecules like this with lines to represent shared electrons

and dots only for non-bonding electrons.

These two diagrams of a hydrogen molecule are equivalent

because one line, which is a single bond, represents 2 shared electrons.

In the same way, two lines between atoms would be a double bond

and would be the sharing of 4 electrons.

An example of a molecule with a double bond is oxygen, which looks like this.

Notice that in this Lewis diagram both oxygen atoms have 8 valence electrons,

4 from the double bond and 4 from the lone pairs of electrons.

By the way, 2 dots together are called a lone pair of electrons.

Some molecules contain triple bonds, which we write using 3 lines that represent the

sharing of 6 electrons.

An example of a molecule with a triple bond is nitrogen, which looks like this.

Once again, notice that both nitrogen atoms have 8 valence electrons,

6 from the triple bond and 2 from the lone pairs of electrons.

Okay, how do you actually draw the Lewis diagram of a molecule?

Let's start with water, H2O.

There are 5 important steps that you need to follow when drawing the Lewis diagram of

a molecule.

First, count all of the valence electrons in the molecule.

For water, each hydrogen has one electron and we multiply that by two because there

are two hydrogens in the molecule.

The oxygen has 6 valence electrons.

Add those all up, and we have a total of 8 valence electrons for the water molecule.

Step 2, determine the central atom.

The central atom is the one that all of the other atoms will be bonded to.

It is usually the element that there is only one of.

In the case of H2O, because there are 2 hydrogens and only one oxygen, we choose oxygen as the

central atom and write it in the middle.

Step 3, draw single bonds to the central atom.

Step 4, put all of the remaining valence electrons on atoms as lone pairs.

For H2O, we started with 8 valence electrons; we have used four electrons for the two single

bonds, so that leaves 4 more electrons left over.

We put all 4 of those remaining electrons on oxygen instead of hydrogen because hydrogen

is already happy with 2 valence electrons.

Remember, never give hydrogen more than 2 valence electrons.

Everyone else wants 8 electrons, but hydrogen only wants 2.

Step 5, turn lone pairs into double or triple bonds to give every atom an octet

or (duet for hydrogen).

Pause the video and see if all the atoms in our H2O are happy.

Because each hydrogen has 2 electrons, and the oxygen has 8 electrons, everyone is happy,

and there is no need for double or triple bonds, which means that our Lewis diagram

of water is now complete.

All right, let's try one more example just to make sure we've got this.

Draw the Lewis diagram of sulfur trioxide.

Once again, the first step is to count all the valence electrons.

There is one sulfur with six valence electrons, and there are 3 oxygens with 6 valence electrons

each.

6 times 3 gives us 18 valences electrons for the 3 oxygens.

The total would be 6 + 18, which equals 24 valence electrons.

Step 2, determine the central atom.

This time, sulfur is the central atom because there is only one sulfur in the molecule.

We write sulfur in the middle with the three oxygen atoms all around it.

Step 3, draw single bonds to the central atom.

Step 4, we started with 24 valence electrons, and we have used 6 electrons to make the 3

single bonds.

This means that we have 24 minus 6 or 18 valence electrons remaining.

We now put those remaining 18 valence electrons on atoms as lone pairs.

Count by two's when adding them.

2, 4, 6, 8, 10, 12, 14, 16, and 18.

That's it, we've now used up all of our valence electrons.

Step 5, first pause the video and check to see if any atom does not have an octet or duet.

That's right, the sulfur is unhappy because it only has 6 valence electrons.

So, what can we do to make it happy?

We cannot just give it more electrons, since we don't have any more.

Instead, one of the oxygen atoms can take one of its lone pairs and share those two

electrons with sulfur in another bond.

The double bond between oxygen and sulfur now makes every atom happy with 8 valence electrons.

Be sure to follow these steps when drawing Lewis diagrams.

Thanks for watching.

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