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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6k views

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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Inorganic Chemistry: atomic metal radius and coordination number

On the book "Atkins - Inorganic Chemistry" there is this table: So, if the Molybdenum has an atomic radius equal to 145 pm and this primitive cell is a body-centered cubic lattice (CN = 8), to know ...
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Why the atomic (metallic) radius of gallium is less than that of aluminium?

It is a well known fact that on moving down the group of p-block elements, the atomic radius is expected to increase. However, gallium is an exception. The atomic radius i.e., the metallic radius of ...
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1answer
67 views

Comparison between van der Waals radius and metallic radius

I was reading about different types of atomic radius. It was written that if any atom can possess all the three types of radius, then van der Waals radius will be greater than metallic radius. However ...
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1answer
29 views

Size of atomic shells

Is the distance of some $n^{th}$ shell ($n$ $\neq$ outermost shell) from the nucleus of an atom different for different elements? If so, then how much is the difference or how could we calculate it?
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51 views

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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1answer
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Variation in atomic radii of elements in different blocks?

If we look at the values for the atomic radii (look at the table here), we can see that they rapidly decrease across the period initially. Looking at the second period, The graph is pretty steep ...
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Na+ or Ca2+ . Which ion has the larger radius?

Which ion has the larger radius? Some sites say $r(\ce{Na+}) > r(\ce{Ca^2+})$. Any explanation would be appreciated.
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1answer
3k views

Calculate the radius of an Ag atom

The question I have been given is: Silver atoms in a metallic lattice only fill up $88\,\%$ of the space ($12\,\%$ is empty). The density of silver is $10.5\ \mathrm{g\cdot cm^{-3}}$. Assuming that ...
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21 views

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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1answer
208 views

Do K+ and F- ions have the same ionic radii? [closed]

Since fluorine and potassium form ions to gain the electronic configuration of neon and argon respectively, then shouldn’t $\ce{K+}$ have a greater radius, as argon is larger than neon? Also which ...
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1answer
106 views

H and H- atomic and ionic radius [closed]

A hydrogen anion has a bigger radius than neutral H . Why is this happening ? I mean both electrons exist at the same shell so this is not it. Both H- and H have 1 proton so this is not it as well . ...
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1answer
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Do external electronic shells influence internal ones?

There is a well-known electron shielding effect: negatively-charged internal electronic shell screens external shells from positive nuclei, thus increasing their radii. Thus, 2S orbital radius of Li ...
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0answers
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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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0answers
54 views

Why are atomic radii calculations all over the map? [closed]

If you look up an element on Wikipedia, it will list covalent, ionic, Van Der Waals, high-and-low -spin, and finally 'empirical atomic radius'. Then, on the page for atomic radius, the chart of '...
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23 views

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 ...
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1answer
56 views

Do magnesium and tin have the same volume?

Having the same atomic radii of 145 pm, should one mole of tin and one mole of magnesium take up the same volume? Since tin is much heavier, that means tin is much denser than magnesium. Is this true, ...
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70 views

Relationship between electronegativity and atomic radius [closed]

Would someone please explain in detail the relationship between the two? I understand that atomic radius is related to ionisation energy but I can't see how atomic radius may be related to ...
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47 views

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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2answers
8k views

Regular decrease in the atomic radius of 3d series

While comparing atomic radius, two factors are important: A. Decrease in size due to increase in effective nuclear charge B. Increase in size due to increase in shielding effect I was surprised to ...
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1answer
61 views

Lanthanoid Contraction

Why is the radius of Europium so unusually high and out of the general trend ? Moreover, at different sources I am getting different values of radii. In some (e.g., Wikipedia) the radii are following ...
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1answer
115 views

Radius with Bohr model [closed]

$$r_n = \left(\frac{h^2}{4\pi^2me^2}\right)\times\frac{n^2}{Z} $$ Would I be able to calculate the radius of sodium ion ($\ce{Na+}$) with the help of the above Bohr atomic model formula?
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894 views

Why does the beryllium 2+ ion have a larger radius than a helium atom?

$\ce{Be^2+}$ has an ionic radius of $\pu{45 pm}$, while $\ce{He}$ has a radius of only $\pu{31 pm}$. If they are isoelectronic (they both have two elections in the $\mathrm{1p}$ orbital), and $\ce{Be}$...
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0answers
81 views

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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1answer
268 views

How to get ionic radii for coordination number 12?

I am studying $\ce{ABX3}$ perovskites, and I would like to calculate Goldschmidt tolerance factors for them. The $\ce{A}$ sites in these materials have a coordination number $12$. The Shannon's ...
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1answer
66 views

How am I supposed to answer this? [closed]

First the question gives no units or that these are covalent radii or what, so I assume they are in nanometers and assume an atomic radius. I check my periodic table app and it says a 92pm atomic ...
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1answer
381 views

What is the difference between the Bohr model and the quantum model?

Specifically, Bohrs atom model gives the radius of an atom as 0.53‎Å, while a quantum description offers a similar value. What is the difference between these?
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601 views

Atomic radius definition disproved - Bohr's model to Schroedinger's wave equation

According to the Schrödinger wave equation, Bohr's model of atomic orbitals is disproved and a new formalism that describes atomic orbitals is introduced. It follows that the definition of ...
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Atomic radii of Sc, Ti, Fe, and Co

The atomic radius of Sc is $\pu{162pm}$, Ti is $\pu{147pm}$, $\ce{Fe}$ is $\pu{126pm}$, and that of $\ce{Co}$ is $\pu{125pm}$. The electronic configuration of $\ce{Fe}$ is $\ce{[Ar] 3d^6 4s^2}$, and ...
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1answer
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Which has a greater atomic radius, Cl- , K+ , S-2 , Ca+2 , Ar? [duplicate]

How can I know that? I only know that while we going to the right side at the table so the radius is decreasing. And while we going down, so the radius is bigger. But how can I check that radiuses ...
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2answers
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Why is the atomic radius of krypton smaller than that of potassium?

A potassium atom comprises 19 protons and 18 core electrons. Those electrons screen 18 protons worth of Coulomb force. Therefore, there is one proton worth of Coulomb force attracting the valence ...
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183 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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1answer
353 views

Radial probability curve [closed]

Can somebody give me a clue on how to solve the question in the picture for me given below
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1answer
144 views

Comparing size of ions lithium, gallium ions

How is the size of $\ce{Li+}$ ($\pu{0.68}$) larger than $\ce{Ga^3+}$ ($0.62$)? This is very difficult for me to understand why they say that size of Li+ with 3 protons and just 2 electrons should be ...
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0answers
140 views

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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2answers
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Why are the atomic radii of iron, cobalt, nickel, and copper almost the same?

We have to select the set of elements which will have almost the same atomic radii: $\ce{O, S, Se, Te}$ $\ce{Li, Be, B, C}$ $\ce{Fe, Co, Ni, Cu}$ I googled the atomic radii of the third set and ...
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2answers
655 views

What is the difference between the mean radial distance and the most probable radial distance of an orbital?

I was reading JD Lee's Concise Inorganic Chemistry and it has given some values of mean radial distance which is increasing from s to p to d orbital. I had earlier read that the most probable radial ...
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2answers
98 views

How do I list these elements according to their radius?

$\mathrm{Z=33,\ Z=37,\ Z=9,\ Z=31}$ Since we shouldn't look at the periodic table, I found their groups and periods, what should I do next?
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1answer
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Why can't we calculate the atomic radii of noble gases?

My book says that only the Van der Waal's radius of noble gases can be measured as these gases generally do not form compounds (except Xenon.) Then why can't we just calculate the atomic radii by ...
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1answer
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Ionic bond and ionic radii in FeS

Which of the following statements is true regarding an ionic bond in $\ce{FeS}$? Iron atoms gain electrons and sulfur atoms lose electrons. Iron and sulfur ions bond by ...
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1answer
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What is the atomic radius of chlorine?

I'm trying to study for chemistry and there's a question in my book about identifying an element based on its atomic radius. But when I looked up the value for chlorine, I found different answers from ...
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3answers
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Variation in atomic sizes in the transition elements

From left to right across a period, effective nuclear charge increases in the transition series, just like in the p block, and so atomic size decreases. Here the electrons are being added to the d ...
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3answers
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Is it possible to compress an atom to infinite density? [closed]

I know, by nature, normally atoms are stable. But I wonder, if it is possible to compress an atom, say the Hydrogen atom, to infinite density by applying external force? After all, electrons and ...
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0answers
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Is significant figure important for atomic radius calculations? [closed]

Is significant figure important for atomic radius calculations? Calculate the radius of a vanadium atom, given that V has BCC crystal structure, a density of $\pu{5.96 g/cm^3}$, and an atomic ...
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1answer
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Why is the difference between atomic radii of Na and K greater than that of Rb and Cs?

I am aware that this question has already been asked here: Why does the "gap" between atomic radii get smaller down the periodic table?. However, I was wondering if there is a way to ...
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1answer
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Niobium has a density of 8.57 g/cm3 and crystallizes with the body-centered cubic unit cell. Calculate the radius of a niobium atom

Here is my question Niobium has a density of $8.57 \pu{g/cm^3}$ and crystallizes with the body-centered cubic unit cell. Calculate the radius of a niobium atom. Here is my solution
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1answer
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Atomic radius and nuclear effective charge in a group [closed]

Why even though the effective nuclear charge increases in gruop from top to bottom , the atomic radius increases too? Shouldn’t it decrease with more effective charge on valance electrons and ...
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2answers
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Calculate the atomic radius of iridium atom

I was delaying with this question as seen below. Calculate the radius of iridium atom, given that Ir has an FFC crystal structure, a density of $\pu{22.4 g/cm^3}$ and atomic weight of $\pu{192.2 ...
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1answer
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How do I find the diameter of an aluminum atom from its density and atomic mass? [closed]

I am supposed to find the diameter of an aluminum atom using data given by my teacher. Here is the data: \begin{array}{cc} \text{Density of Aluminum}& \pu{2.70 g/cm3}\\ \text{Atomic Mass of ...
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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: $$\...