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Questions tagged [atomic-radius]

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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Newer ionic radii data than Shannon's 1976 compilation?

Shannon, R. D., 1976, Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides: Acta Crystallographica Section A, v. 32, p. 751–767. DOI: 10.1107/...
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Gap in ionic radii

The above picture was shown in a presentation by my prof in inorganic chem as we were discussing ionic radii more in depth (all in pm). These are all isoelectronic radii. Notice the sudden leap in ...
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“Crystal radius” vs “Ionic radius”

What is the difference between crystal radius and ionic radius? For $\ce{NaCl}$ for example the ions combine to a crystal, and I would have guessed they are equal. But I then found an example of data, ...
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Why are the Covalent Radii of Ruthenium and Osmium So Similar?

Osmium and Ruthenium have covalent radii 144 and 146 respectively (according to Wikipedia). How are these values so similar when Osmium has 32 more electrons, with another filled p, s, and f orbital ...
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How/where can I find a reliable atomic radii table?

I am currently working on a periodic table to include it in a experimental chemistry book and I would like to include non-bonded atomic radii data so it would be easier for the students to learn about ...
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Why do some elements such as polonium not follow the trend of decreasing atomic radius?

Most of the periodic table follows the trend of increasing radius as you move down a family and decreasing radius as you move across a period. Why is this trend not observed for polonium?
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For a given period, why is the boiling point of the halogen greater than that of the noble gas?

The boiling point of bromine, a halogen, is $\pu{58.8^\circ C}$, while the boiling point of krypton, the noble gas in the same period as bromine, is $\pu{-153.4 ^\circ C}$. I thought that the larger ...
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2k views

Ionic radius of Al[3+] compared to K[+], Ca[2+], S[2-], and Cl[-]

I came across this question: Which of the following is bigger? $$\ce{K+, Ca^2+, Al^3+, S^2-, Cl-}$$ Now, I know that the radius decreases as the period progresses to the right and increases ...
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878 views

How to determine relative size of polyatomic ions?

How would you determine the size of a polyatomic ion? For example when determining which ion is bigger, $\ce{NH2-}$ or $\ce{I-}$, what would you use to determine the size difference? I know that $\...
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What will happen if electron as a wave undergo destructive interference while travelling in its Orbit?

Today I came across a justification of Bohr's angular momentum quantization using the De- Broglie's hypothesis. The justification said that since the electrons are having wave nature also then while ...
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181 views

Mismatch in the trends of atomic size and atomic radius

In the periodic table, the atomic radius decreases as we move from left to right in a period. However, the atomic volume should also decrease as a result of the decrease in atomic radius, as volume is ...
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1k views

Ar atomic radius Vs. Mg2+, Al3+ and F-

I find it difficult to understand why the Atomic radius of $\ce{Ar}$ is lower than the ionic radius of $\ce{Mg^2+}$ and $\ce{F-}$, and higher than $\ce{Al^3+}$. According to the tables I've seen: $$\...
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Does electron shielding increase or stay constant moving LEFT to RIGHT across a period?

Does electron shielding increase or stay constant moving left to right across a period? I have read about both, and I just want to know which one is right. I believe that electron shielding remains ...
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43 views

Co vs Rh atomic radius

Why is the empirical atomic radius for both Co and Rh 135 pm, the same? Source
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402 views

The ionic radius of aluminium(III) vs. the covalent radius of neon?

I was wondering if it is a valid comparison to look at the ionic radius (noble-gas-like configuration) of a metal and the covalent radius of a noble gas. Specifically, $\ce{Al^{3+}}$ and $\ce{Ne}$. ...
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51 views

How would I find an apporpriate dopant element for a lattice

I am trying to figure how would I go about finding a dopant element that would fit in a copper lattice? I already have the data for the atomic dimensions and structure (available below), however how ...
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394 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/...
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1answer
4k views

Ionization energy and Electron Affnity

Which of the following statements correctly interprets the relationship between ionization energy, atomic radius Electron affinity when comparing two atoms. The correct choice as per my instructor ...
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1answer
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Bohr's postulate of quantisation of angular momentum

The Bohr's postulate of quantisation of angular momentum can be written in a formula as $mvr = nh/(2π)$ where $m$ is mass of electron $v$ is its velocity $r$ is the radius of that shell $h$ is ...
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Contraction in Lanthanides and Actinides

How does the lesser shielding effect of 5f electrons(relative to 4f electrons) reduce the change in atomic radius (here, metallic radius) between 2 consecutive elements in Actinides (when compared ...
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Shielding effect on an electron

Whenever we calculate the screening constant on an $\ce{f block} $ element, we start calculating from the electron present in the $\ce{(n-2)f orbital}$ and then leftwards. I was a bit confused that ...