A Level Chemistry Revision "Electron Configuration"
Summary
TLDRThis educational video script from the 'Three Science' series teaches viewers how to determine electron configurations of elements. It explains the concept of atomic orbitals, subshells, and the energy levels associated with them. The script outlines three key rules for electron assignment: filling the lowest energy orbitals first, allowing two electrons per orbital with opposite spins, and distributing electrons across degenerate orbitals before pairing. Examples are provided, starting with hydrogen and helium, then challenging viewers to determine lithium's configuration and finally nitrogen's, which has seven electrons. The script promises to explore more complex examples and exceptions in a subsequent video.
Takeaways
- 🔬 The video is a chemistry lesson focused on electron configuration in elements.
- 🌐 An atomic orbital is a region around the nucleus where up to two electrons with opposite spins can reside.
- 📚 There are different types of orbitals: s, p, d, and f orbitals, each with unique characteristics.
- 📈 Subshells, which are groups of orbitals of the same type in the same shell, have varying energies.
- 📉 The energy of subshells increases as we move away from the nucleus.
- ✅ Three key rules for assigning electrons to orbitals are: fill the lowest energy orbitals first, each orbital can hold two electrons with opposite spins, and distribute electrons into individual orbitals before pairing when energies are the same.
- 💡 The video provides examples of how to assign electrons to orbitals, starting with hydrogen and helium.
- 🚀 Electron configuration is a shorthand notation that represents the distribution of electrons in an atom's subshells.
- 🌿 The example of nitrogen is used to illustrate how to determine electron configuration, which for nitrogen is 1s² 2s² 2p³.
- 🔍 The video concludes with a teaser for the next part, which will cover more complex examples and exceptions to the rules of electron configuration.
Q & A
What is an atomic orbital?
-An atomic orbital is a region around a nucleus where electrons are most likely to be found and can hold up to two electrons with opposite spins.
What are the different types of orbitals mentioned in the script?
-The different types of orbitals mentioned are s, p, d, and f orbitals.
What is a subshell in the context of atomic orbitals?
-A subshell consists of all orbitals of the same type within the same shell, such as the 3d subshell shown in the script.
How does the energy of subshells change as we move away from the nucleus?
-As we move away from the nucleus, the energy of the subshells increases.
What are the three rules for assigning electrons to atomic orbitals?
-The three rules are: 1) Orbitals with the lowest energy are filled first. 2) Up to two electrons with opposite spins can occupy the same orbital. 3) If orbitals have the same energy, electrons are placed in individual orbitals before pairing them.
How is the electron configuration of hydrogen represented in the script?
-The electron configuration of hydrogen is represented as 1s1, indicating one electron in the 1s subshell.
Why do electrons in the same orbital have opposite spins?
-Electrons in the same orbital must have opposite spins due to the Pauli Exclusion Principle, which states that no two electrons in an atom can have the same set of quantum numbers.
What is the electron configuration for helium as described in the script?
-The electron configuration for helium is 1s2, indicating two electrons in the 1s subshell with opposite spins.
How does the script describe the electron configuration for lithium?
-The electron configuration for lithium is 1s2 2s1, showing the first two electrons in the 1s subshell and the third electron in the 2s subshell.
What is the process for assigning the remaining electrons to orbitals in nitrogen as per the script?
-For nitrogen, the first two electrons go into the 1s subshell, the next two into the 2s subshell, and the remaining three electrons go into the 2p subshell, with the electron configuration being 1s2 2s2 2p3.
Why are individual orbitals in the 2p subshell not shown in the electron configuration?
-Individual orbitals in the 2p subshell are not shown in the electron configuration because it only represents the subshells, not the individual orbitals within them.
Outlines
🔬 Electron Configuration Basics
This paragraph introduces the concept of electron configuration in elements, building on the understanding of atomic orbitals established in a previous video. It explains that different subshells have different energies and that electrons fill the lowest energy orbitals first. The video script outlines three key rules for assigning electrons to atomic orbitals: 1) filling the lowest energy orbitals first, 2) allowing up to two electrons per orbital with opposite spins, and 3) distributing electrons into individual orbitals before pairing them when orbitals have the same energy. Examples are given to illustrate these rules, starting with hydrogen and helium, and then moving on to lithium, which has its third electron placed in the 2s orbital of the second shell. The paragraph concludes with an exercise for the viewer to draw the electron configuration for nitrogen, which has seven electrons.
Mindmap
Keywords
💡Atomic Orbital
💡Subshell
💡Electron Configuration
💡Electron Spin
💡Energy Levels
💡Pauli Exclusion Principle
💡Hund's Rule
💡Electron Shells
💡Nitrogen
💡Helium
💡Lithium
Highlights
Introduction to electron configuration in elements
Explanation of atomic orbitals and their capacity to hold electrons
Differentiation between s, p, d, and f orbitals
Concept of subshells and their composition
Energy levels of subshells and their increase with distance from the nucleus
Three rules for assigning electrons to atomic orbitals
Rule 1: Lowest energy orbitals are filled first
Rule 2: Up to two electrons per orbital with opposite spins
Rule 3: Electrons fill individual orbitals before pairing in same orbital
Demonstration of electron assignment in hydrogen
Electron configuration notation for hydrogen
Explanation of electron spin notation
Electron configuration for helium
Electron configuration for lithium including the 2s orbital
Assignment of nitrogen's seven electrons into orbitals
Electron configuration for nitrogen: 1s2 2s2 2p3
Introduction to exceptions to the electron filling rules
Teaser for the next video with more complex examples
Transcripts
[Music]
hi and welcome back to three science
lessons by the end of this two-part
video you should be able to work out the
electron configuration of elements okay
in the last video we saw that an atomic
orbital is a region around a nucleus
that can hold up to two electrons with
opposite spins we saw that there are
several different types of orbitals and
we call these the s P D and F orbitals
we also saw that a sub shell consists of
all of the orbitals of the same type in
the same shell and I'm showing you the
3d subshell here so in this video we're
going to look at how we assign electrons
to different atomic orbitals the first
key idea you need to understand is that
different sub shells have got different
energies I'm showing you the energies of
some of the sub shells here now I should
point out that at this stage I'm only
looking at a small number of sub shells
we've been looking at the rest in the
next video as you can see as we move
away from the nucleus the energy of the
sub shells increases now in order to
show how electrons fill the orbitals we
need to follow three rules these are
quite straightforward so let's look at
them now firstly orbitals were the
lowest energy are filled first secondly
we can have up to two electrons in the
same orbital but they must have opposite
spins and lastly if we have orbitals
with the same energy then we put
electrons into individual orbitals
before we pair them and that's because
electrons in the same orbital repel
coming up I'm going to show you some
examples of how to put electrons into
orbitals and I'll give you want to try
for yourself
[Music]
okay so let's look at some examples of
how to put electrons into atomic
orbitals we're gonna start with hydrogen
which has got one electron in this case
the lowest energy orbital is the 1s
orbital and shell 1 so here's our
electron and you'll notice that were
using an arrow to show the electron spin
now I should point out that if you're
following the AQA spec then you need to
show an electron using an arrow like
this instead however for the LC aspect
we show electrons using a normal level
which is what I will use now another way
of writing this is to use a shorthand
version showing just the sub shells this
is called the electron configuration in
the case of hydrogen the 1s sub shell
contains one electron so the electron
configuration of hydrogen is one s one
let's look at the element helium helium
has two electrons again the lowest
energy orbital is 1s so our first
electron goes there remember that each
orbital can hold up to two electrons so
that means that our second electron can
also go into the 1s orbital now you'll
notice that we flipped the spin of the
second electron and that's because
electrons in the same orbital must have
opposite spins because helium has two
electrons in the 1s sub shell the
electron configuration of helium will be
1s - okay let's look at lithium now
lithium has three electrons again we can
put the first two electrons into the 1s
orbital like this the 1s orbital is now
full so the third electron now goes into
the second shell the lowest energy
orbital in the second shell is the 2's
orbital so that's where the electron
goes this means that the electron
configuration of lithium is 1s2 2s1
okay I'd like you now to draw the
electrons in their orbitals for the
element nitrogen nitrogen has got seven
electrons I'd also like you to work out
the electron configuration from nitrogen
so pause the video and try this yourself
okay so just like before the first two
electrons go into the 1s sub shell and
here they are the next two electrons go
into the two s subshell we now have
three more electrons to assign now
you'll notice that all of the P orbitals
and the 2p sub-shell have the same
energy remember that if we've got
orbital
with the same energy then we put
electrons into individual orbitals
before we pair them so here are three
electrons and the 2p orbitals the
electron configuration for nitrogen is
1s2 2s2 2p3 as you can see the electron
configuration does not show the
individual orbitals in the 2p sub-shell
and that's because the electron
configuration only shows the sub shells
not the individual orbitals in the next
video we look at more complicated
examples of how orbitals are filled and
we look at two elements that are
exceptions to the rules and explain why
[Music]
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