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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.

Atomic radius is the 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. Atomic radius are of three types:

  1. Ionic radius - for ionic species like $\ce{NaCl}$
  2. Covalent radius - for species like $\ce{Cl2}$
  3. van der Waal's radius - for non-bonding species like neon

In each case, the radius is defined as half of the distance of the two atoms/ions. In the third case, it is actually half the closest distance of approach, since the atoms don't bond with each other.

134 questions
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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.
Robert
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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 $\ce{Be}$ has more protons to attract them, why doesn't…
Johnny Dollard
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The explanation on atomic size

I always receive two type of explanation for the decreasement of atomic size for elements across the period. Explanation according to proton number This explanation is from my teacher. The proton number of elements increases across the period. The…
Simon-Nail-It
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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 different sources: 79 pm 175 pm (from the…
sksumii13
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Why does being "bonded" decrease atomic size?

I have a furiously overwhelming question- Why is the atomic size of noble gases larger than the atomic size of the previous halogen when atomic sizes decrease across a period? I did search it on the net and asked my teacher but everyone says that…
MartianCactus
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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, oxide. Any student who has been trained in trends…
Brinn Belyea
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How to list elements according to their radius? For example Ag, Cd, Au Can you check the accuracy of these sentences I've created?

I've asked a similar question before, but now I want to find out the real rule. Pleas tell me if my interpretation is correct: Cd, Ag , Au (increasing ray order). This happens because although we know that period and group effect the radius length,…
Annalian Loverre
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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
Mascular
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Co vs Rh atomic radius

Why is the empirical atomic radius for both Co and Rh 135 pm, the same? Source
Ashwin Ramaswami
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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 $\ce{Ne}$. This website gives me the impression that for…
timaeus222
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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?
Annalian Loverre
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Effective nuclear charge on 3p electron of aluminum

Using Slater's rule I calculated the effective nuclear charge on 3p electron of aluminium as: Config: $\ce{1s^2 (2s^2 2p^6) (3s^2 3p^1)}$ $S = 2(0.35) + 8(0.85) + 2 = 9.5$ $Z_{eff} = Z - S = 3.5$ The Wikipedia page states its value as 4.066. Which…
Joy
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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, or is there an error in my thought process.
Hack Delta
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Atomic radius and nuclear effective charge in a group

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 eventually more force affecting them?
Hesam
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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 $\pu{192.2 g/mol}$. Let me show you how my teacher solved…
Cargobob
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