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Aliya Jain 2B
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Joined: Wed Sep 11, 2019 12:16 am


Postby Aliya Jain 2B » Sun Oct 27, 2019 3:05 pm

"Place the following ions in order of increasing ionic radius: S^2-, Cl^-, P^3-." Since all of these ions have the same amount of electrons, are we supposed to take into account core charge?

Posts: 103
Joined: Sat Sep 14, 2019 12:16 am

Re: 1F.3

Postby 805422680 » Sun Oct 27, 2019 3:12 pm

You have to know that a higher negative charge means that there are more electrons added to the atom to achieve stability. There is greater electron-electron repulsion when electrons are added to the valence shell. As you move left to right across the periodic table, the atomic radius decreases. By adding more electrons, the positive charge of the nucleus is spread out more evenly. Thus, as P has the lowest number of protons and thus the lowest positive charge, it will be the biggest ion, followed by S and then Cl.

Ashley R 1A
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Joined: Sat Aug 24, 2019 12:16 am

Re: 1F.3

Postby Ashley R 1A » Sun Oct 27, 2019 4:06 pm

To add on, the easiest way I like to remember it is with the amount of protons, since the amount of electrons is the same with these ions. Protons have a positive charge which will draw negatively-charged electrons towards the nucleus, so if an ion has more protons in the nucleus, their radius will be smaller because it can bring outer electrons inwards.

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Joined: Sat Jul 20, 2019 12:15 am

Re: 1F.3

Postby aishwarya_atmakuri » Sun Oct 27, 2019 4:09 pm

You need to look at the number of protons and effective nuclear charge to determine the order.

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