For questions about the atomic radius - a measure of the size of an atom, usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding "cloud" of electrons.

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### How can we measure the atomic radius of an atom?

The definition of atomic radius is half the average internuclear distance of an atom. But many times I've been told that it is not possible to handle a single atom. Thus how can we measure the ...
5k views

### Finding orbit radius using the Bohr model and Rydberg equation

To start with its a homework problem, quite lengthy. A particle of mass equal to 208 times the mass of an electron moves in a circular orbit around a nucleus of charge $+3e$. Assuming the Bohr ...
2k views

### Which element has larger atomic radius — beryllium or xenon?

I say that xenon radius is smaller comparing to beryllium, but my friend says otherwise. What I think is that xenon is down in periodic table comparing to beryllium (3 periods down) and it's far ...
112 views

### Acid-base chemistry - determining stability [closed]

I am learning about acid-base reactions and how to identify whether an acid is strong or not by looking at the conjugate base. The more stable a conjugate base the stronger the acid. However, two of ...
873 views

### How to know which ionic compound have the highest lattice energy without knowing the values of the radii?

Given two ionic compounds, for instance: $$\ce{CaS} \quad \mathrm{or} \quad \ce{KCl}$$ What is the procedure to predict which of the two have the highest lattice energy (in absolute value)? (...
2k views

### Van der Waals Radius clarifications

I just read about van der Waals radius and had some questions about it. Would it be correct to say that in general, van der Waals radius decreases as we move from left to right in the periodic table? ...
10k views

### Why the radius of noble gases is more than the halogens or the previous groups?

Noble gases have a larger radius than the halogens. Sometimes it is greater than the radius of group I elements. Why it is like that? When we talk about radius of noble gases what type of radius ...
327 views

126 views

### Atomic number $Z$

If electrons were spin-$\frac {3}{2}$ instead of spin-$\frac {1}{2}$ , what would be the atomic number $Z$ for the first noble gas ?
409 views

### What radius best represents reaction distance?

Molecules must be within a certain distance for a reaction to begin as well as satisfying a myriad of other factors. Whilst the exact distance varies from reaction to reaction, is their any distance/...
403 views

### Why does the “gap” between atomic radii get smaller down the periodic table?

The question asks: why is the difference in atomic radii between $\ce{K}$ and $\ce{Na}$ larger than the difference in atomic radii between $\ce{Cs}$ and $\ce{Rb}$? I do have some kind of notion that ...
28k views

### Why does Mg2+ have the ionic radii bigger than Ca2+

If they were atoms, $\ce{Mg}$ should have a smaller radii. How does this change?
514 views

### Is it possible to calculate atomic radius with electron configuration?

I need to know whether is it possible to calculate the atomic radius according to the number of electrons and electron configuration. Or is there any way to calculate the atomic radius using common ...
325 views

### XRD-Shorter distance between planes than actual radius of atoms/or cell parameter

I'm solving problems related to X-ray diffraction, and I get these results which apparently are correct. My question may be dumb, but I just can't see how the interplanar distance might be shorter ...
1k views

### Which is the bigger ion, F- or O-?

Well, according to the proton-electron ratio $\ce{O-}$ should be bigger than $\ce{F-}$ What about the charge/electron density in $\ce{F}$? Will it not affect the size of the atom of $\ce{F-}$?
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### Can ionic and atomic radii be compared?

Can ionic and atomic radii be compared? For example, this is a common problem in some intro chem courses: Rank the following from smallest to largest: sodium ion, magnesium ion, neon, fluoride, ...
For which pair of species is the difference in radii the greatest? (A) $\ce{Li}$ and $\ce{F}$ (B) $\ce{Li+}$ and $\ce{F^-}$ (C) $\ce{Li+}$ and $\ce{O^2-}$ (D) $\ce{O^2-}$ and ...
I'm told that in the normal cubic system there are $\frac18$ of an atom at each corner and these atoms' radius are such that $a = 2r$ ($a$ is the lattice constant, $r$ radius of an atom). In bbc (...