Across a period vs. Down a group

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YashDeshmukh1D
Posts: 42
Joined: Fri Sep 29, 2017 7:05 am

Across a period vs. Down a group

Postby YashDeshmukh1D » Wed Oct 25, 2017 9:44 am

If we can understand that going across a period from left to right results in an increase of nuclear attraction (since no energy levels are being added to offset the increased number of protons) and that going down a group results in a decrease of nuclear attraction (since the increased energy levels lead to more shielding between electrons and nucleus), which of these is greater in strength?

For example, would boron have a greater or smaller atomic radius than chlorine?

StephanieDoan3B
Posts: 21
Joined: Fri Sep 29, 2017 7:07 am

Re: Across a period vs. Down a group

Postby StephanieDoan3B » Wed Oct 25, 2017 12:08 pm

I don't think we have to or are able to use trends to compare atoms of elements not in the same period or group.

Mitch Walters
Posts: 45
Joined: Fri Sep 29, 2017 7:07 am

Re: Across a period vs. Down a group

Postby Mitch Walters » Wed Oct 25, 2017 12:19 pm

This might be something that can only be known from experimental values.

Gobinder Pandher 3J
Posts: 21
Joined: Fri Sep 29, 2017 7:07 am

Re: Across a period vs. Down a group

Postby Gobinder Pandher 3J » Sun Oct 29, 2017 10:45 pm

Typically, if we need to know, the atomic radii will be given to us already. In my high school chemistry class, if we ever compared the different ionization energies between two elements these values were usually given to us (either on the back of our periodic table or in the problem). I'd assume the same for atomic radii.


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