Aufbau Principle (Periodic Table Labels).mp4

Summary

This vodcast explains how to label the periodic table to understand electron configurations, focusing on the Aufbau principle. It highlights how electrons fill lower energy orbitals first and introduces labeling sections for s, p, d, and f blocks. The video also covers orbital overlap, particularly the 3d and 4s energy levels, and guides viewers through the proper order for filling orbitals across the periodic table. Finally, it reassures viewers that they don't need to stress over the f-block elements due to their limited role in most chemistry studies.

Takeaways

• 📝 The video explains how to label the periodic table with electron configurations using the Aufbau principle.
• 🔋 The Aufbau principle states that electrons fill lower energy levels first and higher energy levels last.
• 🧊 Energy levels overlap starting from the third level, making the order of filling orbitals confusing without labels.
• 🔍 Helium is temporarily considered part of the second group on the periodic table for electron configuration purposes.
• 🔢 The energy levels are labeled 1 through 7, indicating the primary levels where electrons reside.
• 🟧 The periodic table is divided into blocks: the S block (first two columns), P block (right side), D block (middle), and F block (bottom).
• 🪜 The order of electron filling starts at 1s, then 2s, 2p, 3s, 3p, and continues in a specific sequence influenced by energy levels.
• ⚠️ Due to orbital overlap, the 4s orbital fills before the 3d orbital because 4s has lower energy.
• 📉 The F block elements, found in the bottom two rows, have less focus since they are radioactive and not part of typical chemistry studies.
• ✅ The main takeaway is that labeling the periodic table helps identify the correct sequence for electron configurations, which follows the Aufbau principle from left to right and down each row.

Q & A

What is the Aufbau principle?

The Aufbau principle states that electrons fill orbitals from low energy to high energy, starting with the lowest available energy level before moving to higher ones.

Why is helium penciled in as part of the second group on the periodic table?

Helium is temporarily penciled into the second group of the periodic table because it helps with organizing electron configurations, even though it belongs to the noble gases in Group 18.

How are energy levels labeled on the periodic table?

Energy levels on the periodic table are labeled as 1, 2, 3, 4, 5, 6, and 7, corresponding to the principal quantum numbers that describe the different energy levels electrons can occupy.

What does the S block on the periodic table represent?

The S block on the periodic table represents the first two columns, where all elements have their outermost electrons in S orbitals.

How do you identify the P block on the periodic table?

The P block includes the elements in Groups 13-18 (excluding helium). It is found on the right side of the periodic table and includes elements whose outermost electrons are in P orbitals.

What is the D block, and where is it located on the periodic table?

The D block, located in the center of the periodic table, includes transition metals. The outermost electrons of these elements are in D orbitals.

What is the significance of the F block on the periodic table?

The F block includes the lanthanides and actinides, which are elements located below the main body of the periodic table. These elements have their outermost electrons in F orbitals.

Why does the 4S orbital fill before the 3D orbital?

Although the 3D orbital belongs to the third energy level, the 4S orbital has a lower energy, so it fills before the 3D orbital due to orbital overlap.

What is the electron filling order for energy levels and sublevels?

The order is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.

Why is less focus placed on the elements in periods 6 and 7, particularly the F block?

Elements in periods 6 and 7, especially in the F block, are typically radioactive and do not participate in the types of chemistry that are usually studied in detail, so they are less emphasized.

Outlines

00:00

🔬 Understanding Electron Configurations and the Aufbau Principle

This section introduces the Aufbau Principle, which explains how electrons fill orbitals starting with the lowest energy level and progressing to higher ones. The speaker discusses the complexity of electron configurations once the third energy level is reached, where orbital overlaps occur. To make this process clearer, labels are added to the periodic table. The first step is to pencil in helium as part of the second group and ensure the energy levels (1-7) are labeled. The speaker also suggests blocking off different regions (S, P, D, and F sublevels) on the periodic table to help understand the electron configuration sequence.

05:03

🧪 Electron Configuration Sequence and Overlaps

This section describes the sequence in which electrons fill orbitals based on their energy levels. The process starts with the 1s orbital, followed by 2s, 2p, 3s, and 3p orbitals. A key point is the energy overlap between 4s and 3d orbitals, where 4s is filled before 3d despite being part of the higher fourth energy level. The speaker guides the viewer through labeling these sections on the periodic table, helping to clarify the order of electron configurations. The discussion also touches on the later periods, emphasizing that the lower part of the periodic table (especially the F block) involves radioactive elements, which are less relevant to the chemistry being studied.

Keywords

💡Aufbau Principle

The Aufbau Principle is a rule in atomic theory that states electrons fill orbitals starting with the lowest energy levels before filling higher energy levels. In the video, this principle is used to explain how electrons are arranged in different sublevels (S, P, D, F) across the periodic table, ensuring a proper understanding of electron configurations.

💡Energy Levels

Energy levels refer to the fixed distances from the nucleus where electrons can exist. The video mentions seven energy levels (1 through 7), and each level can hold electrons that are organized into orbitals. These levels help guide the order in which electrons fill the periodic table, which is central to understanding electron configurations.

💡Sublevel

Sublevels, such as S, P, D, and F, represent divisions within an energy level where electrons are likely to be found. The video explains how these sublevels are laid out on the periodic table and how they help classify the elements by their electron configurations. For example, the 'S sublevel' includes elements in the first two columns of the table.

💡Periodic Table

The periodic table organizes elements by increasing atomic number and by similar chemical properties, which relate to their electron configurations. In the video, the periodic table is used to visually guide the labeling of sublevels and energy levels, helping explain the arrangement of electrons in atoms.

💡Helium

Helium is a special case in the video, as it is part of the second group on the periodic table despite being located in the first group. The presenter suggests 'penciling it in' to the second group to help with understanding electron configurations, highlighting how it fits with other elements in the S sublevel.

💡Electron Configuration

Electron configuration describes how electrons are distributed among different orbitals within an atom. The video explains how to label the periodic table to determine the correct order of electron filling based on the Aufbau Principle, energy levels, and sublevels. It provides a step-by-step method to understand electron distribution.

💡Overlap of Orbitals

The overlap of orbitals occurs when higher energy orbitals (like 4s) are filled before lower orbitals (like 3d), as explained in the video. This overlap can cause confusion when determining electron configurations, but labeling the periodic table helps to clarify the correct order of electron filling.

💡S Block

The S block on the periodic table consists of the first two columns and includes elements where the outermost electrons are filling the S sublevel. In the video, the presenter suggests highlighting this block to easily identify elements like hydrogen and helium, as well as alkali and alkaline earth metals.

💡D Block

The D block is located in the middle of the periodic table and includes elements where the D sublevel is being filled, such as transition metals. The video explains how the 3D sublevel comes after the 4S sublevel due to the overlap in energy levels, and viewers are encouraged to label this block for easier identification.

💡F Block

The F block is found at the bottom of the periodic table and includes the lanthanides and actinides. The video points out that electrons fill the 4f and 5f orbitals in this region, but these elements are less relevant to the chemistry discussed since they are mostly radioactive.

Highlights

Introduction of the ALB principle, which states that electrons fill low energy levels first and high energy levels last.

Clarification that the first energy levels (1, 2, 3) are filled sequentially, but overlap occurs after the third energy level, causing confusion.

The importance of labeling helium as part of the second group on the periodic table.

Instructions for marking energy levels (1 through 7) on the periodic table to better understand electron configuration.

Using Sharpies or highlighters to block off the S, P, D, and F sublevels on the periodic table for easy reference.

Electrons first fill the 1s sublevel, followed by the 2s, 2p, 3s, and 3p sublevels.

Explanation of orbital overlap: the 4s sublevel is lower in energy than the 3d, so electrons fill the 4s before the 3d.

Step-by-step guide for labeling the periodic table to help track the electron filling order for sublevels, including the 3d and 4p groups.

Discussion on how after the 6s sublevel, electrons move to the 4f block before continuing with the 5d sublevel.

Labeling the F block elements at the bottom of the periodic table for periods 6 and 7.

The final electron configuration order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.

Reassurance that understanding the filling order in periods 6 and 7 is less critical, as these elements are primarily radioactive and not studied in-depth in chemistry.

Focus is mainly on understanding the electron configuration of elements from period 1 to period 5 on the periodic table.

Encouragement to have the periodic table fully labeled before proceeding with more advanced lessons.

Concluding advice to watch the next vodcast for further instruction on how to apply this electron configuration information in future lessons.

Transcripts

what I'm going to go over in this

vodcast is how we got all those labels

on our periodic table in electron

configurations there's this rule called

the albal principle and the ALB

principle says that electrons like to

fill low energy first and high energy

last so when we talk about filling low

energy first we're talking about the

first energy level the second energy

level the third energy level but the

problem is once we get into the third

energy level orbitals start to overlap

and the order can get a little confusing

by putting labels on our periodic table

it can tell us exactly which order to

follow so we know what to do when we're

doing our configurations so the first

thing that you want to do is on your

periodic

table I would like you to pencil in a

helium right here so we're going to draw

helium in there we're not going to erase

it on the other side but we want to

pencil it in there because we're going

to count helium as part of this second

group on our periodic table for the time

being

and then the next thing you want to do

is make sure that you have the energy

levels labeled um on your periodic table

these numbers are most likely already

there my periodic table is going to look

slightly different than yours but the

energy levels would be 1 2 3 4 5 6 and 7

those would be the energy levels the

next thing I would like you to do is

block off the Su levels so the first

thing we'll

do is we're going to draw draw a

box around the S

subel so if you grab those first two

columns and you can take some Sharpie

markers if you have some or any kind of

highlighter that'll work on your

periodic table and block that off and

label that as the S suble all the

elements in this block are in the S

suble and then if you want to you can

switch

colors and come over here

and we're going to label the S

block so we're going to go right along

here excluding

helium down the side grab those guys on

the bottom

row and we're going to label that as the

P

block and then if you want to switch

colors

again we can label the D

Block which would be in the

middle and then the F

block would be the elements down at the

bottom

here so pause the vodcast for a minute

and go ahead and make sure you have

those labels on your periodic table

before we move on

all right now that you've done that what

we'll look at is the order in which the

electrons fill these orbitals the first

place that electrons are going to go is

into the 1s subl we call this the 1s

because it's the first energy level S

Sub

level the second place electrons are

going to go is into the 2s second energy

level s subev if you then come across

the periodic table the next group that

you run into would be called 2 p 2 p

because this is the second energy level

and the P

suble so we have 1s 2 s then we come

across 2 p you read this just like you

would a page in a book left to right

down the page then the electrons would

go into the

3s and the 3p again this is called 3p

because third energy level P sub level

now you would expect 3D to come next

however

this is where the overlap occurs where

the 4S is actually lower energy than the

3D so we would call this group the 4S

but then right here we would want to

label this

group as the 3D row so if you stick that

label on your periodic table that'll

help remind you that this row is called

the

3DS then we have the four

Ps in the next row we would start with

5S again fifth energy level s suble so

this would be the

5S this group would be called the

4ds this is still the five PS the only

place that it's offset is here in the

middle the sides are still the

same then we would come down to the 6s

you would expect the 5D to come next

however if you look at the atomic

numbers 55 56 57 58 59 60 you realize we

got to jump down here first before we do

the five D's so after the 6s we would

label this section as the 4

FS okay all the way down the line then

look 69 70 71 number 72 is back up here

so we're going to label this group the 5

D's then we have the 6

PS

7s and then 87 88 89 90 so we're going

to come down here and label this group

the 5

FS 100 101 102 103 104 is right here

these would be called the

6d's and then the 7 PS so the order that

we follow for electrons to fill orbitals

is just across and down the periodic TBL

so we do 1 S 2

S 2

p 3

S 3

p 4S

3D 4

P

5S

4D 5 P 6s then we come down to 4

FS

5D

6p and then the last row

7s

5f 6D and 7p you really don't have to

stress over the order too much down here

when we get to um period 6 and 7

um in the F block down here because

those elements don't undergo the

chemistry that we're going to study

anyway those are all radioactive so most

of our focus is going to be kind of from

here on up in the periodic table we go

through this so what you want to do at

this point is make sure you have all of

these labels on the periodic table and

then check in with the next vodcast and

that'll give you the lesson that we

follow after that