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 to reason in terms of atomic radius in this case?

I am trying to solve a pset from MIT $5.111$ class. The question is which of vanadium and molybdenium has the largest radius. The right answer (given in the pset answers) is: molybdenum. In class, we ...
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1 vote
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### Atomic radius decreasing across a Periodic Table row - does the RPD of an orbital change depending of the element considered?

I have a concern regarding the RPD of an orbital. Does the RPD of an orbital depend on the $Z$ (i.e. on the element under consideration) ? Especially, can the RPD of an orbital "shrink" to ...
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### Is the $2p$ RPD defined along the z-axis?

In MIT $5.111$ class (lecture $6$), we are to compare the most probable radius of a $2s$ orbital and a $2p$ orbital. The graph used by the professor represents the RPD versus $r$: My question is: in ...
• 255
184 views

### Ionic radii of cations and anions

My textbook mentions that across a period from left to right, the ionic radius of atoms decreases. I'm a bit puzzled because negative ions in the same period have an extra shell. I get the part about ...
96 views

### Does Cu+ have a greater ionic radius than Sr2+?

Although Strontium is in group 2, reducing the number of electrons as it becomes ionized makes it group 18, period 4 in terms of electrons. Therefore, ionized Strontium (Sr2+) is in the same period as ...
562 views

### Comparison of atomic radii of boron and beryllium

Let me write down a couple of facts and this will be easier for you to know the essence of the question. Radius of boron is smaller than beryllium. Ionization energy of boron is smaller than ...
• 143
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### Size of Lanthanum

I was going through the values of atomic and covalent radii of the d-block elements. The atomic radii of $\ce {Sc},\ce {Y}$ and $\ce {La}$ are $164, 184$ and $187$ pm respectively (Source: Wikipedia). ...
146 views

### Why does atomic radius decrease across periods? [closed]

My textbook says that this happens because the number of protons, and thus the total positive charge, increases - a greater attractive force acts on each electron. The book says that this is despite ...
• 63
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### How does O2- have the largest radius [closed]

Why is the correct option O^2-, aren't all of them equal since they all have the same number of energy shells and same number of electrons in them
250 views

### Why ionic radius increases with negative charge?

Here's my understanding: An ion with a negative charge has gained electrons. Hence the negative charge. With a greater negative charge, there should be more attraction towards the positive charge. As ...
408 views

### If the effective nuclear charge of Beryllium(Be) is less than Sodium's(Na), how is the ionization energy of Be higher than Na?

According to Slater's rules the effective nuclear charge of Beryllium and Sodium is 1.95 and 2.20 respectively. That means that the outermost electron of Na feels a stronger attraction from the ...
1 vote
116 views

### What role does atomic radius play in the strength of a covalent bond?

How exactly do atomic radii influence the strength of a covalent bond? For instance, if I had a carbon atom covalently bonding to a fictitious nonmetal atom $\ce{X}$ and another nonmetal atom $\ce{Y}$ ...
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1 vote
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### Compare the covalent character of ZnCl2, CdCl2,HgCl2

I want to know how to arrange the covalent character of ZnCl2, CdCl2, and HgCl2. By Fajans' rules, We know that a smaller cation equals higher covalent character. We also know that atomic size ...
• 199
1 vote
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### Which ionic radius is most relevant for anticipating co-crystalization?

In the context of anticipating the likeliness that elemental impurities co-crystalize into the crystals containing an element of similar radius (see this question), which is the relevant radii to ...
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### Proof for equation of radial probability distribution curve

So my textbook says the equation for this is $$P(r) = 4\pi r^2\Psi^2$$ It also gives the volume of the shell formula $$\mathrm{d}V = \frac 43 \pi(r+\mathrm{d}r)^3 - \frac 43 \pi r^3$$ which I ...
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1 vote
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### Atomic Radius of Manganese and Chromium

It is clearly a general trend that the atomic radii of the 3d elements in ascending order of atomic weight, leads to the following trend as in the graph below. But, it was pointed out to me that, Mn ...
• 795
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### Ionic radii of transition metal ions in the presence of weak field and strong field ligands

‎‎‎‎‎‎‎‎‎ In the graph given in this image,‎ I was told by my teacher‎ that whenever we start filling the eg orbitals there is an increase in the radius because these orbitals face the ligand directly ...
1 vote
1k views

### Why are hydrated lithium ions' radii larger than hydrated sodium ions' radii?

Why are hydrated lithium ions' radii larger than hydrated sodium ions' radii i.e. $r_\ce{Li+(aq)}>r_\ce{Na+(aq)}$? If ionic radii increase down the group i.e. $r_\ce{Li+}<r_\ce{Na+}<r_\ce{K+}$...
7k views

### Which atom is the smallest atom?

Is hydrogen or helium the smallest atom? My teacher said that the smallest atom is the helium atom, but I think that the smallest atom is the hydrogen atom. It has a single electron and a single ...
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### Why does dissolved oxygen concentration decrease with increasing atomic number of metals?

I am looking at how metal ions ($\ce{Fe^2+}$, $\ce{Ni^2+}$, $\ce{Cu^2+}$, $\ce{Zn^2+}$, and $\ce{Ag+}$) affect the biochemical oxygen demand in water and used the Winkler's method to find out the ...
333 views

### Distance of subshells from nucleus [closed]

Which subshell is more closer to the nucleus.4f or 6s? 6s gets filled first so does it have to be more closer to the nucleus?
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### Forcing atoms closer together [closed]

Is there a method in chemistry to alter the energy of atomic bonds by forcing atoms closer together in a smaller volume? Similar to how pressure squeezes atoms closer together.
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### Covalent atomic radii: oxygen vs nitrogen

Many books state that $R_\ce{N} > R_\ce{O}$ which is in accordance with the general trend. However, some books say that $R_\ce{O} > R_\ce{N}$ because of repulsion caused by pairing of electrons. ...
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1 vote
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### Reason for needing multiple radii for the same atom [duplicate]

Why do we need different types of atomic radii? Why can't there be just one radii for an atom?
237 views

### How to calculate electric force on valence electron?

In order to understand the periodic trends more fully, I wanted to calculate the net force exerted on the electron (with the highest principal quantum number and azimuthal quantum number) of an atom. ...
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1 vote
968 views

### How to compare size of subshells?

For the same principal quantum number, on increasing the value of the azimuthal quantum number does the average radius of the subshell increase or decrease? In other words, which out of, say, 3s, 3p, ...
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### In the gold foil experiment why didn't thallium form? [closed]

When alpha particles hit the gold nucleus shouldn't they form thallium. More over shouldn't it also ionize the gold or any atom it hits how does it remain unchanged unionized?
1 vote
297 views

### Why doesn't core charge increase down a group? [closed]

Atomic radius increases down a group because the electrons feel a lesser attraction to the positive nucleus (due to shielding from inner shells). Why then, doesn't core charge decrease seeing as core ...
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### How value of energy of elecron becomes more negative and radius of orbit decreases with increase in the value of atomic number? [closed]

I know how energy of elecron and radius of orbit depends upon principal quantum number......But how it depends upon atomic number?
1 vote
1k views

### Why is the strontium ion smaller than the potassium ion? [closed]

The ionic radius of the $\ce{Sr^2+}$ ion is $\mathrm{132\,pm}$, while the ionic radius of the $\ce{K^+}$ ion is $\mathrm{152\,pm}$. Why is this the case? I would have thought that since $\ce{K^+}$ has ...
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### Why is platinum denser than gold?

The atomic masses of gold and platinum are 196.96657 u and 195.084 u respectively, meaning that (on average) an individual gold atom is heavier than an individual platinum atom. At the same time, the ...
196 views

### True muonium energy levels [closed]

In a true muniom(muon-antimuon atom) do the energy levels match with that of the hydrogen's? The core is lighter for about 100 times but the muon is 100 times heavier than the electron so it would ...
783 views

### Shielding effect of d electrons

In transition elements shielding effect is observed . Due to this zinc shows abnormality in atomic size. But at the same time we also say that gallium has same similar size as aluminium due to poor ...
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### Shielding effects and atomic size [closed]

The atomic size on going from aluminum to gallium decreases because of poor shielding effect of the $(n-1)d$ electrons, but on going from copper to zinc, the size increases due to the same shielding ...
6k views

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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### 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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### 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 Plank's ...
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### 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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