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18 votes

Which atom is the smallest atom?

The volumes of the nuclei are negligible compared to the atomic radii (like a "pea in a soccer/football/cricket stadium"). The higher the nuclear charge, the closer the electrons to the ...
Karsten's user avatar
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15 votes
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Na+ or Ca2+ . Which ion has the larger radius?

The thing is that you need to know the coordination environment in the first place as ionic radii are C.N.-dependent. From Shannon's canonical paper "Revised effective ionic radii and systematic ...
andselisk's user avatar
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13 votes
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Why does the beryllium 2+ ion have a larger radius than a helium atom?

You are mixing apples and oranges. Or, to be more precise, an ionic radius for $\ce{Be^2+}$ with coordination number (C.N.) 6 and van der Waals radius of $\ce{He}$. To make it clear I compiled data ...
andselisk's user avatar
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13 votes

Why is platinum denser than gold?

Since OP is still in the high school, I'll try to explain it simply as possible using mathematical manipulation (hoping OP is more familiar with mathematics than chemistry). Both gold and platinum ...
Mathew Mahindaratne's user avatar
10 votes

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

As you may know, atomic orbitals are wave functions, solutions of the Schrödinger equation for an atomic system. In a perfectly spherical system you may express an orbital as a function depending on ...
schneiderfelipe's user avatar
10 votes
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Why does magnesium have a greater ionization energy than lithium?

The book has omited the other factors. The short answer is: In spite of the bigger atomic radius, the valence electrons of magnesium are attracted by the greater net electrostatic force compared to ...
Poutnik's user avatar
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9 votes

Newer ionic radii data than Shannon's 1976 compilation?

tldr; it's very difficult to determine consistent additive ionic radii For various reasons, I've gone back to look at covalent radii recently (e.g., for estimating bond lengths). In that case, there ...
Geoff Hutchison's user avatar
8 votes
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Covalent atomic radii: oxygen vs nitrogen

The van der Waals radius of nitrogen is larger than that of oxygen, and has been calculated as such for quite a long time. $$ \begin{array}{lll} \hline \text{Reference} & R_\ce{O} & R_\ce{N} \\...
Aniruddha Deb's user avatar
7 votes

Why does being "bonded" decrease atomic size?

As Paul has pointed out, there are many different ways of defining atomic radii. ron has also pointed out that the trend goes in the opposite direction from what you said. For instance, according to ...
schneiderfelipe's user avatar
7 votes

What is the atomic radius of chlorine?

There is no such thing as unified atomic radius. An atomic radius is a class consisting of van der Waals radii $R_\mathrm{vdW}$ (steric interactions), covalent radii $R_\mathrm{cov}$, and ionic radii $...
andselisk's user avatar
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6 votes
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Why the atomic (metallic) radius of gallium is less than that of aluminium?

First, you have to look at the definition of metallic radius, which is the half distance between two atoms in a lattice. It has a significant dependence on crystal structure. Tanget relevant to ...
A.K.'s user avatar
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6 votes

Why does being "bonded" decrease atomic size?

The first thing you should realize is that there are various definitions of the size of the atom. One distinguishes for example the covalent radius, the Van der Waals radius and the ionic radius. The ...
Paul's user avatar
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6 votes

Lother Mayer curve

It is an interesting question, and I am not completely sure on everything I write below. First of all, atomic volume is defined as the "quotient obtained by dividing the atomic weight of an ...
S R Maiti's user avatar
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5 votes

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

From Ref. 1: Unlike a ball, an atom doesn't have a fixed radius. The radius of atom can only be found by measuring the distance between the nuclei of two touching atoms and then halving that distance....
xavier_fakerat's user avatar
5 votes

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

The Bohr model is a comparatively simple model, whereas the quantum description is part of the huge theory of quantum mechanics, so to list all the differences including implications would need to ...
user183966's user avatar
5 votes
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Predict the order of ionic radius

You're right about the expected order. From largest to smallest the expected order would be: $\ce{_{53}I^-}\quad$ = [Kr] $4d^{10}\text{ }5s^2\text{ }5p^6$ = [Xe] $\ce{_{34}Se^{2-}}$ = [Ar] $3d^{10}\...
MaxW's user avatar
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5 votes
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Why is the radius of the caesium cation smaller than that of the chloride anion?

This is something students often forget when comparing radii: shells are not simply additive. If you move along eight elements to go from lithium to sodium, you are not only filling the second shell ...
Jan's user avatar
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5 votes

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

In multi-electron atoms the energy of the s, p and d orbitals for a given $n$ is determined primarily by shielding by inner electrons and penetration of the orbital towards the nucleus. As s orbitals ...
porphyrin's user avatar
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5 votes
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How to get ionic radii for coordination number 12?

The commonly used method of obtaining ionic radii for higher coordination numbers (C.N.) is to extrapolate values from the Shannon's scale [1] using the relationship between ionic radius and ...
andselisk's user avatar
  • 38.3k
5 votes

True muonium energy levels

The theory for a muon-antimoun "atom" is essentially the same as any hydrogen-like atom, just with masses changed. See this Wikipedia page for the relevant formulae for relativistic (Dirac) and non-...
StephenG - Help Ukraine's user avatar
5 votes

In the gold foil experiment why didn't thallium form?

The Rutherford formula, as derived, assumes purely elastic scattering from the Coulomb force. No formation of a compound nucleus is considered. Generally, for most of the initial experiments, the ...
Jon Custer's user avatar
  • 8,600
5 votes

Distance of subshells from nucleus

The question is misguided by the obsolete idea of shells and subshells as separated exclusive regions of the space around the nucleus. All orbitals largely overlaps and statistical distribution of ...
Poutnik's user avatar
  • 42.4k
4 votes

Why the atomic (metallic) radius of gallium is less than that of aluminium?

With each additional proton that is added to a nucleus, the attraction between the nucleus and the electrons is increased and thus the wave function is contracted. This trend is most obvious when ...
Jan's user avatar
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4 votes
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Why is the ionic radius of Al(3+) smaller than that of Li+?

The size of the 1s orbital in $\ce{Li+}$ and $\ce{Al^3+}$ is not necessarily the same. In fact, they are quite different because of the much larger effective nuclear charge in $\ce{Al^3+}$. One can ...
orthocresol's user avatar
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4 votes

Why can't we calculate the atomic radii of noble gases?

Covalent radius is measured as the distance ($r_\text{cov} = d/2$) between the nuclei of two bonded atoms (covalent). But, if you try to do the same for noble gases/inert gases (good luck!), as they ...
yousuf QURAITI's user avatar
4 votes

Which element has larger atomic radius -- beryllium or xenon?

You cannot really effectively compare the atomic radii of xenon and beryllium empirically; the atoms are too far apart. Once you remove yourself from direct neighbours, it is generally not possible to ...
Jan's user avatar
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4 votes

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

This is how I would do the calculation... Given data: $$\text {Weight of crystal} = \pu{92.90638 g/mole} \ce{->[Round] \pu{92.906} g/mole}$$ $$\text {Density} = \pu{8.57 g/cm^3}$$ Ok, the density ...
MaxW's user avatar
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4 votes
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Comparing size of ions lithium, gallium ions

That is impressive. What you may need to bear in mind is that as the nuclear charge increases, all the electron orbitals move in closer to the nucleus. You may have been assuming, consciously or ...
Christopher Grayce's user avatar
4 votes

How value of energy of elecron becomes more negative and radius of orbit decreases with increase in the value of atomic number?

Atomic number is proportional to the atomic kernel charge. From the classical electrostatics we know that potential around a charge $Q$ is: $$U=-\frac{Q}{4\pi \epsilon_0 r}$$ So it's obvious it the ...
Poutnik's user avatar
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4 votes
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Atomic Radius of Manganese and Chromium

The reason for your confusion may be the difference between atomic radius and ionic radius, as well as the specific comparison between ions that your source was making. Comparing manganese and ...
Scott Cookson's user avatar

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