Valence Electrons and the Periodic Table

Summary

The script offers an educational exploration into atomic structure, focusing on electrons and their significance. It explains the nucleus, energy levels, and shells, then delves into valence electrons, the most crucial for chemical reactions. The periodic table is used to demonstrate how to determine an atom's valence electrons, and electron dot diagrams are introduced as a tool to visually represent these electrons. The video script systematically covers how the number of valence electrons corresponds to an element's position in the periodic table, highlighting patterns across different columns.

Takeaways

• 🔬 Atoms consist of a nucleus with protons and neutrons, surrounded by electrons occupying energy levels or shells.
• 📊 The periodic table is a key tool for determining the number of valence electrons in an atom, which are the electrons in the outermost energy level.
• 🚀 The number of valence electrons can be deduced by an atom's position in the periodic table, with each column representing a specific number of valence electrons.
• 🔋 The first energy level can hold up to two electrons, the second can hold up to eight, and this pattern continues with more energy levels further out.
• 💡 Valence electrons play a crucial role in chemical reactions and bonding, as they are the most accessible for interaction with other atoms.
• 🌟 Electron dot diagrams, or Lewis diagrams, are used to visually represent the valence electrons of an atom, with each dot representing a single electron.
• 📚 The number of valence electrons corresponds to the group number in the periodic table, allowing for quick determination of an atom's reactivity and bonding properties.
• 🔄 The filling of electron shells follows a specific order, with the innermost shells filling first before electrons occupy the outer shells.
• 🌈 Noble gases like helium, neon, and argon have completely filled valence shells, which contributes to their chemical stability and inertness.
• 🚨 The script emphasizes that while the diagrams used are simplified and not perfectly accurate, they are sufficient for understanding basic atomic structure and electron configuration.

Q & A

What are the spaces in an atom where electrons can live called?

The spaces in an atom where electrons can live are called energy levels or shells.

How many electrons can the first energy level or shell hold?

The first energy level or shell can hold two electrons.

What is the significance of valence electrons in an atom?

Valence electrons are the most important electrons in an atom as they are involved in chemical bonding and reactions.

How can you determine the number of valence electrons an atom has by using the periodic table?

You can determine the number of valence electrons by looking at the column in which the atom is located on the periodic table.

What is the maximum number of electrons that the second energy level can hold?

The second energy level can hold a maximum of eight electrons.

How does the number of valence electrons in an atom relate to its position in the periodic table?

The number of valence electrons in an atom is directly related to its position in the periodic table, with the number increasing as you move across a period.

What is the term for the diagrams that show the number of electrons an atom has?

The diagrams that show the number of electrons an atom has are called electron dot diagrams or Lewis diagrams.

Why are hydrogen, lithium, and sodium said to have one valence electron each, despite having different numbers of total electrons?

Hydrogen, lithium, and sodium are said to have one valence electron each because they each have one electron in their outermost energy level, which is the definition of valence electrons.

What is the pattern of valence electrons for the elements in the second column of the periodic table?

The elements in the second column of the periodic table have two valence electrons in their outermost shell.

How do you represent an atom with a full valence shell in an electron dot diagram?

An atom with a full valence shell is represented in an electron dot diagram by placing the maximum number of dots around the element symbol, typically eight for most elements, or two for helium, without leaving any empty spaces.

Outlines

00:00

🔬 Understanding Electrons and Atoms

The script introduces the concept of electrons and their role within atoms. It begins by examining the structure of an atom, highlighting the nucleus with protons and neutrons, and the spaces where electrons reside, visualized as 'parking spots' or 'theater seats.' The discussion then moves to energy levels or shells, which are circular paths that electrons might take around the nucleus. The script simplifies the representation of electrons for educational purposes, emphasizing the importance of the first three energy levels or shells. The periodic table is introduced as a tool to determine the number of electrons in an atom, particularly focusing on the valence electrons, which are crucial for chemical reactions. The script concludes with a practical demonstration of how to fill these electron spots using the periodic table, starting with hydrogen and lithium as examples.

05:02

🚀 Filling Electron Shells and Valence Electrons

This section delves into the process of filling electron shells in atoms, using sodium as an example to illustrate how electrons are distributed across different energy levels. The script emphasizes the concept of valence electrons, which are the electrons in the outermost shell and are significant in chemical bonding. A pattern is identified where atoms in the first column of the periodic table have one valence electron each. The script then introduces electron dot diagrams, or Lewis diagrams, as a method to represent the valence electrons of elements. Examples are provided to show how to draw these diagrams for elements in the first column, such as lithium, which has one valence electron.

10:03

🌐 Exploring the Valence Electrons Across the Periodic Table

The script continues to explore the periodic table, focusing on how the number of valence electrons varies across different columns. It explains that each column corresponds to a specific number of valence electrons, with the second column having two valence electrons, and this pattern continues as columns progress. The script provides a step-by-step guide on how to draw electron dot diagrams for elements in the second column, such as beryllium and magnesium, which have two valence electrons. The process is then generalized to other columns, with examples given for boron, carbon, nitrogen, oxygen, and fluorine, each illustrating the increasing number of valence electrons as one moves across the periodic table.

15:06

🌟 The Special Case of Helium, Neon, and Argon

The final section of the script discusses the unique valence electron configurations of helium, neon, and argon. It points out that while most elements in the noble gases column have eight valence electrons, helium only has two, yet its valence shell is fully occupied. The script concludes by summarizing the rule that the number of valence electrons can be determined by the column in which an element is located on the periodic table, with each column representing a specific number of valence electrons, from one to eight. This understanding is crucial for predicting an element's chemical behavior.

Keywords

💡Electrons

Electrons are negatively charged subatomic particles that orbit the nucleus of an atom. They are a fundamental component of all matter and play a crucial role in chemical reactions and bonding. In the video, electrons are likened to 'parking spots' or 'theater seats' that can be filled by electrons in various energy levels or shells around the nucleus.

💡Atom

An atom is the basic unit of matter, consisting of a nucleus containing protons and neutrons, surrounded by electrons. The video uses a simplified model of the atom to explain how electrons are arranged in energy levels or shells, emphasizing the importance of understanding atomic structure.

💡Valence Electrons

Valence electrons are the outermost electrons of an atom, which play a key role in determining the chemical properties of an element. The video highlights that valence electrons are the most important for chemical reactions and that their number can be determined by the element's position on the periodic table.

💡Energy Levels/Shells

Energy levels or shells are the regions around an atom's nucleus where electrons are most likely to be found. These levels are organized at varying distances from the nucleus, with the first shell closest to the nucleus holding up to two electrons, and subsequent shells holding more. The video uses the analogy of 'parking spaces' to explain how these levels fill up with electrons.

💡Periodic Table

The periodic table is a tabular arrangement of chemical elements by atomic number, electron configuration, and recurring chemical properties. The video uses the periodic table to demonstrate how to determine the number of valence electrons in an atom by looking at its position.

💡Electron Dot Diagrams

Electron dot diagrams, also known as Lewis diagrams, are a way to visually represent the valence electrons of an atom. The video teaches how to draw these diagrams for different elements, showing the number of valence electrons as dots placed around the element's symbol.

💡Nucleus

The nucleus is the central part of an atom, containing protons and neutrons. It is the focus of the video's discussion of atomic structure, where the number of protons determines the element and the number of electrons in a neutral atom.

💡Protons

Protons are positively charged subatomic particles found in the nucleus of an atom. The video explains that the number of protons in an atom, known as the atomic number, determines the element and the number of electrons in a neutral atom.

💡Neutral Atom

A neutral atom is an atom with an equal number of protons and electrons, resulting in no net electrical charge. The video assumes atoms are neutral when discussing the number of electrons, which is a common assumption in basic chemistry.

💡Chemical Bonds

Chemical bonds are the forces that hold atoms together in molecules or compounds. While not explicitly defined in the video, the discussion of valence electrons implies their role in forming these bonds, as atoms tend to combine in ways that fill their outer electron shells.

💡Element

An element is a substance that consists of atoms with the same number of protons. The video uses elements as examples to explain how to determine the number of valence electrons and how to draw electron dot diagrams, emphasizing the periodic table's role in this process.

Highlights

Exploration of electron spaces in an atom and their significance.

Introduction to valence electrons as the most important type in an atom.

Method to determine valence electrons by periodic table position.

Explanation of drawing electron dot diagrams to represent electron count.

Visual representation of an atom's nucleus with protons and neutrons.

Description of energy levels or shells as electron 'parking spots'.

Understanding that the first energy level can hold up to two electrons.

Demonstration of filling electron spots in atoms using the periodic table.

Procedure for determining the number of electrons in hydrogen based on its proton count.

Explanation of how lithium's three electrons fill the first energy level.

Pattern recognition of one valence electron in the first column of the periodic table.

Electron dot diagrams for elements in the first column, illustrating one valence electron.

Beryllium's four electrons and their arrangement in energy levels.

Observation that elements in the second column have two valence electrons.

Electron dot diagrams for second column elements showing two valence electrons.

Boron's electron configuration with three valence electrons in its outer shell.

General rule for the third column elements having three valence electrons.

Carbon and Silicon's electron configuration with four valence electrons.

Nitrogen's five valence electrons and the pattern in the fifth column elements.

Oxygen's six valence electrons and the pattern for elements in the sixth column.

Fluorine's seven valence electrons and the near-full valence shell pattern.

Neon's eight valence electrons and the full valence shell pattern for noble gases.

Understanding that helium, despite having only two valence electrons, also has a full valence shell.

Transcripts

in the next couple minutes we're going

to talk a lot about electrons first

we're going to start out looking at an

atom and looking at the spaces in an

atom where electrons can live then we'll

learn about the most important type of

electrons in an atom these are called

the valence electrons we'll learn how

you can figure out how many valence

electrons and atom has by looking at

where that atom is on the periodic table

and finally we'll look at how you can

take an atom and draw one of these

electron dot diagrams for it that shows

how many electrons it has so let's get

started okay so check out this diagram

of an atom I have here in the middle is

the nucleus with protons and neutrons

and I look at all of these little

circles each one of these circles

represents a spot that could hold one

electron you can think of these as like

parking spots for electrons or like

theater seats for electrons and these

spots for electrons are organized into

these circles these circles are called

energy levels or shells you can think of

these energy levels or shells sort of

like they show the paths that the

electrons would take as they're spinning

around the nucleus here but also energy

levels our shells

arrange electrons into different groups

that are varying distances from the

center of the end okay like so for this

first group this first energy level or

shell can hold two electrons really

close to the nucleus moving out a little

bit we get to another shell that can

hold eight electrons and they're

spinning out here and then even further

out we have another group that can hold

eight electrons now it keeps going from

here and there are more and more energy

levels or shells but it gets a little

bit tricky so I just wanted to focus on

these first three to give you an idea of

how they work now if you've learned a

little bit about atoms already you might

know that the

have drawn this here this isn't the most

perfectly accurate way to represent

electrons and atoms but you know what it

doesn't matter for our purposes right

now we just want to learn the basics

drawing and thinking about atoms like

this is totally fine so don't worry that

it's not super accurate okay so let's

look at what happens when we start

filling these electrons parking spaces

when we start filling them with actual

electrons so we're going to use the

periodic table for this will go column

by column and here's what I'm doing I've

made this big version of a periodic

table and you can see it looks a little

bit different than the real version of a

periodic table okay look at this whole

thing in the middle this is sort of a

big real periodic table we're not going

to worry about any of these elements in

here in the middle so this whole section

I've put it here

just gotten rid of it we're not going to

worry about it we're only going to focus

on eight columns we're going to focus on

these two right here which I've drawn

they're skipping everything in the

middle and then we're going to focus on

these six over here so don't get

confused by the way I've drawn this

we're just leaving out some of the

elements that we don't want to get into

right now okay

so let's take the first element right

here hydrogen now how many electrons are

there in hydrogen okay well what we got

to do is we got to look it up on the

periodic table and we're going to find

something like this now the periodic

table it doesn't actually tell us how

many electrons are in Hajj it's got this

one here but that refers to the number

of protons so there's one proton in

hydrogen that's what its atomic number

is now if we assume though that this

hydrogen atom if we assume that it

doesn't have a charge then the number of

electrons is going to equal the number

of protons so hydrogen always has one

proton but if the atom is neutral if it

doesn't have a charge it will also have

one electron so let's go back to this

diagram of the atom here let's just

start with this first energy level okay

here's a drawing just the first energy

level let's put a nucleus in here I'm

not actually going to draw the protons

and neutrons instead I'm

going to write the number of protons

okay so this has one proton and P+ is

the abbreviation for protons so 1p plus

in the nucleus now here are the two

spots in this first energy level where

electrons can live there is one electron

in hydrogen so we're going to fill that

in that was really easy right so we got

this first energy level in hydrogen one

of the spots is still empty and one of

the spots is full okay let's move down

here to lithium now if we look up

lithium on the periodic table we're

going to see this 3 which means that

every lithium atom has 3 protons in it

but if that lithium atom is neutral

which we always assume that it is when

we're doing this sort of thing this

lithium atom also has 3 electrons so

we'll start here will be first concerned

with this this energy level that's right

here the first one here I'm going to put

a nucleus in here 3 plus because there 3

protons in here okay so there are 3

electrons so this one is going to get

filled and this one is going to get

filled and now we're going to go out

want to go to the next energy level okay

now that starts getting filled so now

it's going to look like this

now we want to start thinking about the

second energy level the first one is

filled and now one electron is going to

go here in the second energy level okay

so these energy levels they're really

like parking spaces imagine that the

nucleus is a mall right it's like the

parking space is closest to the entrance

of the mall those are the ones that fill

up first and then as more and more

people Park the empty parking spaces

move further and further and further

away from the center of the mall it's

exactly the same way with atoms okay the

first energy levels close to the nucleus

those are the ones that are going to

fill up and then after they're full the

other energy levels further out they're

going to begin to fill up too okay now

let's look at sodium sodium has 11

protons in its nucleus 11 P plus and

we're going to assume that since it's

neutral we're assuming that it's neutral

it has the same number of electrons as

protons so let's start filling them in

one two in the first energy level now

that's full so we're going to start

filling the second energy level three

four five six seven eight nine ten and

finally these are all full but we still

have more electrons so now we're going

to have to bump it to the third energy

level here's a third energy level that

we can start filling in ten of these are

already living in the atom so we're

going to add one more and now there's

one in this third energy level okay now

check this out because this is important

hydrogen lithium and sodium they all

have different numbers of electrons but

there's a pattern here check this out

each one of these atoms has one electron

in the outermost shell okay this one's

full this one's full but then there's

just one here this one's full and then

there's just one here and then hydrogen

here only has one energy level and it

just has one electron in these electrons

one one and one these are the valence

electrons the most important electrons

in an atom we'll talk more about that

later why they're so important but all

you have to know for right now is that

the valence electrons are the electrons

in the energy level that is the furthest

out from the nucleus so in this atom the

valence energy level is the third and it

has one electron and here the valence

energy level this the furthest out is

the second and here the furthest out of

the valence energy level is the first so

there is a pattern each one of these

atoms has one valence electron that's

true not just for these first three

atoms but for every one of the atoms

that's in this first column in the

periodic table I didn't want to do the

electron structures for all of these

others but just trust me that they all

have

one electron okay so now there's a way

that we want to be able to write that to

show that these elements have one

valence electron and what we can do is

draw what we call these electron dot

diagrams they're sometimes known as

Lewis diagrams where we take the element

and then put one dot over it to show

that it has one valence electron here's

how we'd write the electron dot diagrams

for all the elements that are in this

column as an example I'll just take

lithium and write it here so every

single atom in this column has one

valence electron okay let's move on and

take a look at some of the other columns

on the periodic table okay so if

everything here has one valence electron

let's take a look at this call starting

with beryllium beryllium has four

protons if it's electrically neutral

it's going to have four electrons as

well so let's look at how this fills in

we've got four protons here in the

nucleus and now we're going to go one

two in the first energy level and in the

second energy level three four okay so

we've got two electrons in the outer

energy level and look at the wave fill

them in I didn't just fill them in

clockwise here but one went on the top

and then one went on the bottom okay now

magnesium magnesium here has an atomic

number of 12 so 12 protons and 12

electrons if we assume that it is

electrically neutral 12 P Plus here so

12 1 2 3 4 5 6 7 8 9 10 11 12 so what's

the pattern here for this second column

in the periodic table we've got two

valence electrons for magnesium

in the third energy level and we have

two valence electrons for beryllium in

the second energy level so everything in

this column has two valence electrons in

this outermost shell

so we can do is we can draw electron

diagrams for everything in the second

shell here I'm sorry for everything in

the second column here and it looks like

this we take the element symbol and then

we put a dot at the top and a dot at the

bottom and that's how we represent the

electrons for here so I'll just do like

B e beryllium for example do B e dot on

the top dot on the bottom let's go on

okay you're probably getting the hang of

this so we're going to start moving a

little bit faster let's move on to boron

here here's boron this is the structure

of boron and then here is aluminum down

here 13 I'm sorry five protons 13

protons and look at what the structure

of the valence electrons is here we've

got one two three in the valence shell

of boron and for aluminum we've got one

two three in the valence shell the same

is true for these guys here even though

I haven't drawn them out so if in your

if you're in this column you have three

valence electrons an example of this

would be boron and look at how I do the

dots for boron okay I do a dot on the

top just like lithium I do a dot on the

bottom just like beryllium and then I do

a dot here to the left to show that

these all have three valence electrons

and it would be the same way for any of

the elements in this column here okay

let's do all of these as a group okay

this column first has carbon and silicon

in each of these have one two three four

one two three four valence electrons in

their outer shell okay so I can take

this and do a dot up here a dot down

here a dot to the left and then a dot to

the right to show that everything in

this column has for us R for its

electrons now moving on to the right

we've got this column with nitrogen and

phosphorus and all these others and

everything here has one two three four

five one two three four five valence

electrons

so if nitrogen is my example I'm going

to do n dot on the top down on the

bottom left right and now I start

doubling up so now they're going to be

two dots on the top of nitrogen to show

that there are these five valence

electrons for everything that's in this

column you can probably see that there's

a pattern that's developing here oxygen

and sulfur each have you can count them

six valence electrons so I'll take

oxygen as an example now look at what I

do here for drawing the valence

electrons because it gets a little bit

tricky you'll figure out that it's a

little bit tricky okay dot on the top so

anyway six valence electrons for

everything in this column oxygen is the

example dot on the top dot on the bottom

dot on the Left dot on the right now we

double up the one on the top and then we

double up the one on the right okay so

we don't put it on the bottom we put it

on the right so up down left right and

then around clockwise finally for this

column which has at the top of it

fluorine and chlorine both of these have

seven valence electrons which means that

this valence shell is almost full except

for one hole in it so I'll take fluorine

as mine example here dot on the top dot

on the bottom dot on the left dot on the

right now we double up double up on the

top to up here double up on the right

two there and then double up on the

bottom so I've only got one guy here on

the left that doesn't have a pair now

here's the last column that we're going

to talk about okay look at what happens

here well look at helium neon and argon

okay here's helium here's neon and here

is argon notice that argon has eight

valence electrons doesn't have any empty

holes in its valence shell neon also has

eight valence electrons but helium only

has two valence electrons okay so what's

going on in this column is that most of

these

have eight neon has a argon has a as do

Krypton xenon and radon but then there's

helium that only has two but regardless

of whether you have to I mean of whether

you have eight or whether you have two

if you're in this column your valence

shell is totally full okay so here it's

full with eight here it's full with

eight and here it's full with two but

they're all full and there aren't any

empty holes in the shells so as an

example I'm going to use neon

which has eight so one two three four

and now we go clockwise five six seven

eight eight valence electrons for most

of these guys but remember that helium

only has two valence electrons but that

all of them have valence shells that are

totally full with no empty spots so this

kind of sums up everything that we

talked about every atom in this column

has one valence electron every atom in

this column has two valence electrons

and then we skip over this middle

section and we get three four five six

seven and eight so if you know which of

these columns a particular atom is in

you can figure out how many valence

electrons it has