Atomic Radius

Moderators: Chem_Mod, Chem_Admin

Diana A 2L
Posts: 106
Joined: Sat Aug 17, 2019 12:16 am
Been upvoted: 1 time

Atomic Radius

Postby Diana A 2L » Sun Nov 03, 2019 11:52 pm

I don't exactly understand an aspect of the atomic radius trend. Does the atomic radius increase across a row as you keep adding more electrons to the same shell? I know there would be more electron repulsion with lets say flourine rather than boron, so does that cause a radius increase?

abby hyman
Posts: 54
Joined: Thu Jul 25, 2019 12:16 am

Re: Atomic Radius

Postby abby hyman » Sun Nov 03, 2019 11:55 pm

Atomic radius increases as you move from the top right corner of the periodic table to the bottom left. As you add more electrons the radius increases until a new shell is added when you move down to the next period

Sanjana K - 2F
Posts: 102
Joined: Sat Sep 07, 2019 12:17 am
Been upvoted: 1 time

Re: Atomic Radius

Postby Sanjana K - 2F » Sun Nov 03, 2019 11:57 pm

The radius increases as you go down a group (because you're adding more shells) and decreases as you go to the right across a period (because electrons are added to the same shell and the electrostatic attraction increases L-->R so the increasing nuclear charge draws them inwards and radii length decreases).

Diana A 2L
Posts: 106
Joined: Sat Aug 17, 2019 12:16 am
Been upvoted: 1 time

Re: Atomic Radius

Postby Diana A 2L » Sun Nov 03, 2019 11:58 pm

I still don't fully understand. If you're going horizontally across a row does atomic radius increase or decrease? And how about going down a column?

Aprice_1J
Posts: 55
Joined: Wed Sep 18, 2019 12:16 am

Re: Atomic Radius

Postby Aprice_1J » Sat Nov 09, 2019 11:41 am

As you are going towards the right the radius decreases and as you are going up it decreases as well. The reason that it decreases as you go across is because you are adding more protons and those are pulling the electrons in closer to the nucleus making it smaller. It decreases as you go up because there are less orbitals and therefore it is smaller.

Vuong_2F
Posts: 90
Joined: Sat Sep 14, 2019 12:17 am

Re: Atomic Radius

Postby Vuong_2F » Sun Nov 10, 2019 10:11 pm

Diana A 1G wrote:I still don't fully understand. If you're going horizontally across a row does atomic radius increase or decrease? And how about going down a column?


Going horizontally across a period, the radius decreases.
Going vertically down a column, the radius increases.

The vertical trend plays a dominant role in comparison to the horizontal trend.

SimranSangha4I
Posts: 99
Joined: Sat Sep 14, 2019 12:17 am

Re: Atomic Radius

Postby SimranSangha4I » Sun Nov 10, 2019 10:15 pm

The trend would demonstrate that from right to left and top to bottom, the atomic radius would increase.

JTijerina_4A
Posts: 46
Joined: Mon Sep 23, 2019 12:17 am

Re: Atomic Radius

Postby JTijerina_4A » Sun Nov 10, 2019 10:17 pm

Atomic radius increases down the row because there are more electron orbitals and shielding leads to less effective nuclear charge, therefore the size of the atom is greater. Atomic radius decreases across the row from left to right because there is a larger number of protons that increases effective nuclear charge and pulls on the orbitals and decreases radius.

CalvinTNguyen2D
Posts: 102
Joined: Thu Jul 25, 2019 12:16 am

Re: Atomic Radius

Postby CalvinTNguyen2D » Sun Nov 10, 2019 11:28 pm

Atomic radius will increase as you go down the periodic table, and will also increase as you move from right to left each period!

J Medina 2I
Posts: 102
Joined: Wed Sep 25, 2019 12:17 am

Re: Atomic Radius

Postby J Medina 2I » Sun Nov 10, 2019 11:34 pm

Atomic radius increases going left across and down groups of the periodic table. Having higher atomic numbers means having more protons that pull the electrons closer to the nucleus, decreasing the atomic radius as you move right across the periodic table.

Yolanda_Xing_3A
Posts: 37
Joined: Wed Sep 30, 2020 9:52 pm

Re: Atomic Radius

Postby Yolanda_Xing_3A » Sun Oct 18, 2020 10:31 am

Atomic radius increases down the row. Atomic radius decreases across the row from left to right.

Jaclyn Schwartz 2D
Posts: 42
Joined: Wed Sep 30, 2020 9:45 pm

Re: Atomic Radius

Postby Jaclyn Schwartz 2D » Sun Oct 25, 2020 11:35 pm

Atomic radius decreases from left to right and increases as you go down. It increases as you go down because the number of energy levels increases, so there is a greater distance between the nucleus and the outermost orbital. From left to right it decreases because of the charges of the nucleus pulls the electrons closer. But going down a column adds a new shell causing them to be further away.

This little poster might help you understand the trends better
file:///Users/jaclynschwartz/Downloads/mastering-periodic-trends-infographic.pdf

isha dis1k
Posts: 42
Joined: Wed Sep 30, 2020 9:47 pm

Re: Atomic Radius

Postby isha dis1k » Wed Oct 28, 2020 4:29 pm

An easy way to remember it is that as you go down a group, additional levels of shells are added, which adds tangible size to the atom. Across a period, the atomic radii decreases because as more electrons are added in the same shell, the effective nuclear charge, or Zeff, increases. This is the opposites attract mechanism that pulls the nucleus closer to those outer electrons, making it smaller and hence making the ionization energy so large.

Ryan_Kien_1L
Posts: 41
Joined: Wed Sep 30, 2020 9:42 pm
Been upvoted: 1 time

Re: Atomic Radius

Postby Ryan_Kien_1L » Wed Oct 28, 2020 5:34 pm

Atomic radius is largest at the bottom left of the periodic table and weakest at the top left. You can assume that the atom gets bigger when it gains shells which could explain the phenomenon when it moves from top to bottom. The way I was explained the phenomenon from left to right in AP chem was that the greater amount of protons would draw the outer electrons closer to the nucleus. Hope this helps!

Binyu You
Posts: 43
Joined: Wed Sep 30, 2020 9:37 pm

Re: Atomic Radius

Postby Binyu You » Thu Oct 29, 2020 9:50 am

The atomic radius increases when going down a group as more shells are added, whereas the radius decrease when gong from left to right due to the fact that more electrons are added as it gains shells when it gets bigger. Therefore the atomic radius is the highest in the bottom left part of of the periodic table and lowest when in the top left corner.

Malakai Espinosa 3D
Posts: 41
Joined: Wed Sep 30, 2020 9:50 pm
Been upvoted: 1 time

Re: Atomic Radius

Postby Malakai Espinosa 3D » Thu Oct 29, 2020 10:07 am

Atomic radius decreases as you got from left to right across the same period/row. This is because there are more electrons, increasing the attraction towards the nucleus. As we go down a column, the radius increases because the electrons are being added to another energy level.

Samantha Lee 1A
Posts: 44
Joined: Wed Sep 30, 2020 10:05 pm

Re: Atomic Radius

Postby Samantha Lee 1A » Thu Oct 29, 2020 11:16 am

Atomic radius is highest at the bottom left of the periodic table. As you go down a group, another shell is added for the electrons, which increases the radius. It decreases as you move to the right of a period because their is a higher charge between the added electron and the nucleus (positive charge) which pulls in the electrons causing the radius to shrink.

Michael Sun Dis 3G
Posts: 40
Joined: Wed Sep 30, 2020 9:37 pm

Re: Atomic Radius

Postby Michael Sun Dis 3G » Thu Oct 29, 2020 8:02 pm

Going across a row would result in more electron repulsions, though I believe that the increase in the number of protons in the nucleus would overcome this.

Gigi Elizarraras 2C
Posts: 40
Joined: Wed Sep 30, 2020 9:41 pm

Re: Atomic Radius

Postby Gigi Elizarraras 2C » Thu Oct 29, 2020 9:04 pm

The atomic radii will increase as you move down the group because electrons are being added to other shells, and the radii will decrease across a period as an increase in electrons will result in a higher nuclear charge pulling the electrons tighter towards the nucleus. Hope this helps:)

Eric Cruz 3L
Posts: 35
Joined: Wed Sep 30, 2020 9:45 pm

Re: Atomic Radius

Postby Eric Cruz 3L » Sat Oct 31, 2020 1:56 pm

The atomic radius decreases as you down a row. However, when you go across a row, the atomic radius decreases. This is because as you go across the periodic table, there is an increase or protons (+ charge in the nucleus). As a result, this increase of nuclear charge makes the electrons more attracted to the nucleus and consequently come closer to the nucleus. This makes the atom smaller and as a result, make its radius smaller.

Shalyn Kelly 1L
Posts: 41
Joined: Wed Sep 30, 2020 9:55 pm

Re: Atomic Radius

Postby Shalyn Kelly 1L » Sat Oct 31, 2020 2:11 pm

Hi! I think everyone above covered it pretty well, but if you're still having trouble, I like to draw out the trends (color-coded if you want) on a periodic table to kind of solidify them in my memory. So including the others: ionization energy and electron affinity decrease down (vertically) a group/column and increase across (horizontally) a period/row, while atomic radii (and ionic) increase down (vertical) a group and decrease across (horizontal) a period.

David Y
Posts: 40
Joined: Wed Sep 30, 2020 9:49 pm

Re: Atomic Radius

Postby David Y » Sat Oct 31, 2020 5:45 pm

when you add electors the radius increases

Navdha Sharma 1G
Posts: 43
Joined: Wed Sep 30, 2020 9:46 pm

Re: Atomic Radius

Postby Navdha Sharma 1G » Sun Nov 01, 2020 3:07 am

The atomic radius depends upon the effective nuclear charge and number of shells. Across a period, the nuclear charge increases, and the number of shells remain the same, so the size decreases. However down the group, though both the effective nuclear charge and the number of shells increases, the magnitude of the increase in the number of shells overpowers the effective nuclear charge and the atomic size also increases.

Jonathan Banh 1G
Posts: 48
Joined: Wed Sep 30, 2020 9:33 pm

Re: Atomic Radius

Postby Jonathan Banh 1G » Sun Nov 01, 2020 4:49 am

The general periodic table trend for atomic radius is that it decreases as you go across a period (left to right), and increases going down a column. The reason behind the decrease in atomic radius from left to right is due to how the addition of protons, meaning the increase in atomic number, causes the electron cloud to become increasingly attracted to the nucleus of the atom, thus shrinking the size of it. When going down column-wise, the atomic radius increases because of the addition of energy levels, which implies that there is more distance between the nucleus and the outermost parts of the electron cloud. I believe that vertical trend supersedes the influence of the horizontal trend for the majority of elements, if not all of them. For your other question about fluorine vs. boron, fluorine's atomic radius would be smaller than boron due to how it is further right and hence, has more protons.

505598869
Posts: 40
Joined: Wed Sep 30, 2020 9:43 pm

Re: Atomic Radius

Postby 505598869 » Sun Nov 01, 2020 11:43 am

Atomic radii increase down a group and decrease across a period.

Javier Perez M 2J
Posts: 39
Joined: Wed Sep 30, 2020 9:52 pm

Re: Atomic Radius

Postby Javier Perez M 2J » Sun Nov 01, 2020 11:52 am

More electrons = larger radius
However, there is a bigger increment once they start going into other orbitals or passing N=2.

Sandy Lin 1A
Posts: 40
Joined: Wed Sep 30, 2020 9:48 pm

Re: Atomic Radius

Postby Sandy Lin 1A » Sun Nov 01, 2020 11:55 am

The atomic radius will increase as you go down a group because there are additional shells that are farther from the nucleus. The reason why it will decrease across a period is that even though there might be more electrons, those electrons are in the same shell. An increase in the nuclear charge will pull the electrons closer to the nucleus, resulting in a smaller atomic radius.

Serena Song 1J
Posts: 40
Joined: Wed Sep 30, 2020 9:53 pm

Re: Atomic Radius

Postby Serena Song 1J » Sun Nov 01, 2020 3:30 pm

Atomic radius decreases as you go across a period due to increasing nuclear charge. The stronger nuclear charge leads to an increased attraction between the positively charged protons in the nucleus and negatively charged electrons surrounding it. This leads to the electrons, including the valence electrons, being drawn closer to the nucleus, which drecreases the atomic radius. Atomic radius increases as you go down a group due to the shells also increasing as you go down. With each additional shell, the distance between the nucleus and valence electrons grows, meaning that the atomic radius increases.

Jeremy Wei 2K
Posts: 31
Joined: Wed Sep 30, 2020 9:59 pm

Re: Atomic Radius

Postby Jeremy Wei 2K » Sun Nov 01, 2020 3:50 pm

Hi, the atomic radius decreases as you go across the period from left to right because of the increase in valence electrons, while it increases when you go down the groups because there's more subshells. Hope this helps!

Danielle DIS 3K
Posts: 40
Joined: Wed Sep 30, 2020 9:38 pm

Re: Atomic Radius

Postby Danielle DIS 3K » Sun Nov 01, 2020 4:02 pm

The atomic radius increases from top to bottom and right to left of the periodic table :)

Gian Boco 3G
Posts: 41
Joined: Wed Sep 30, 2020 9:36 pm

Re: Atomic Radius

Postby Gian Boco 3G » Sun Nov 01, 2020 4:54 pm

The decrease of atomic radius as you travel across the periodic table horizontally is a result of increasing number of protons, pulling the electrons closer without the electrons jumping further away as they would down a group.


Return to “Trends in The Periodic Table”

Who is online

Users browsing this forum: No registered users and 2 guests