Valence Electrons and the Periodic Table
Summary
TLDRThe 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
- đŹ Atoms consist of a nucleus with protons and neutrons, surrounded by electrons occupying energy levels or shells.
- đ 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.
- đ 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.
- đ 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.
- đĄ Valence electrons play a crucial role in chemical reactions and bonding, as they are the most accessible for interaction with other atoms.
- đ Electron dot diagrams, or Lewis diagrams, are used to visually represent the valence electrons of an atom, with each dot representing a single electron.
- đ 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.
- đ The filling of electron shells follows a specific order, with the innermost shells filling first before electrons occupy the outer shells.
- đ Noble gases like helium, neon, and argon have completely filled valence shells, which contributes to their chemical stability and inertness.
- đš 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
đŹ 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.
đ 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.
đ 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.
đ 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.
Mindmap
Keywords
đĄElectrons
đĄAtom
đĄValence Electrons
đĄEnergy Levels/Shells
đĄPeriodic Table
đĄElectron Dot Diagrams
đĄNucleus
đĄProtons
đĄNeutral Atom
đĄChemical Bonds
đĄElement
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
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