Arraging atoms/ions based on atomic radius

In summary, the conversation discusses the arrangement of atoms and ions based on atomic radius. The question at hand is to arrange Cl, S^{2-}, K, K^{+}, and O in order from smallest to largest. The speaker notes that O has the smallest radius and K has the largest, and that S^{2-} is larger than S and Cl. However, they are unsure how to prove that S^{2-} has a larger radius than K^{+}. The speaker suggests that since K^{+} has more protons, its overall attraction for electrons is stronger and it has a smaller ionic radius.
  • #1
walker
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Arranging atoms/ions based on atomic radius

Hey, I'm in a bit of a bind here. I got a question that deals with atomic radius. The question asks to arrange the following atoms/ions in order from smallest to biggest:

[tex]Cl, S^{2-}, K, K^{+}, O[/tex]

I know just by looking at the periodic table that O has the smallest radius and that K has the largest radius... I also know that since [tex]S^{2-}[/tex] is larger than S and since S is larger than Cl that means [tex]S^{2-}[/tex] is also larger than Cl.

[tex]K^{+}[/tex] is smaller than K and larger than Cl since it has a greater energy level.

Here's my problem... I know that both [tex]K^{+}[/tex] and [tex]S^{2-}[/tex] fall somewhere between the Cl and K atoms... and by looking up the actual radius of the [tex]K^{+}[/tex] and [tex]S^{2-}[/tex] ions I know that the [tex]S^{2-}[/tex] radius is larger than the [tex]K^{+}[/tex] radius but how do i prove this?

Any help would be greatly appreaciated. Thanks!
 
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  • #2
surely both K+ and S2- have the same number of electrons but different number of protons, since K+ has 3 more protons the overall attraction for electrons are stronger so smaller ionic radius?
 
  • #3


Hey there! I can definitely help you out with this question. When arranging atoms/ions based on atomic radius, it's important to remember a few key points. First, as you mentioned, the atomic radius generally decreases from left to right on the periodic table. This is because as you move across a period, the number of protons in the nucleus increases, leading to a stronger pull on the electrons and a smaller atomic radius.

Secondly, the atomic radius generally increases as you move down a group on the periodic table. This is due to the addition of new energy levels, which increases the distance between the nucleus and the outermost electrons.

Now, let's apply this knowledge to the given atoms/ions. We know that O has the smallest atomic radius because it is in the top right corner of the periodic table, meaning it has a high number of protons and few energy levels.

Next, we can compare S^{2-} and K^{+}. As you correctly pointed out, S^{2-} is larger than K^{+} because it has one extra energy level. This means that S^{2-} has a larger atomic radius than K^{+}.

Finally, we can compare S^{2-} and Cl. Since they are both in the same period, we look at the number of protons. S^{2-} has one more proton than Cl, meaning it has a stronger pull on its outermost electrons and a smaller atomic radius.

So, the correct order from smallest to largest is O, Cl, S^{2-}, K^{+}, K. I hope this helps! Let me know if you have any other questions.
 

1. What is atomic radius?

Atomic radius is the distance from the center of an atom's nucleus to its outermost electron. It is typically measured in picometers (pm).

2. How are atoms and ions arranged based on atomic radius?

Atoms and ions are arranged in order of increasing atomic radius, with the smallest atom or ion having the lowest atomic radius and the largest having the highest atomic radius.

3. What factors affect atomic radius?

The main factor that affects atomic radius is the number of electron shells an atom has. As you move down a group on the periodic table, the number of electron shells increases, leading to a larger atomic radius. Additionally, the number of protons in the nucleus and the strength of the electron-nucleus attraction also play a role in determining atomic radius.

4. How does atomic radius impact chemical properties?

Atomic radius can impact chemical properties in a few ways. Larger atoms tend to have weaker attractions between their electrons and the nucleus, making them more reactive. Additionally, the size of an atom can affect its ability to bond with other atoms, as larger atoms may have more space for other atoms to bond to them.

5. Can atomic radius be accurately measured?

Yes, atomic radius can be accurately measured using techniques such as X-ray crystallography or spectroscopy. These methods allow scientists to determine the distances between atoms and the arrangement of their electrons.

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