Questions tagged [atomic-structure]
For questions about the various atomic structure theories, including the Bohr theory. Not to be confused with the actual arrangement of atoms in macroscopic solids ([solid-state-chemistry]) or newer quantum concepts ([quantum-chemistry])
227
questions
0
votes
1
answer
55
views
Electronic configuration and symmetry labels of 3d$^7$ ions
In 3d$^7$ ions, e.g. Co$^{2+}$, the ground state is $^4$F, and it contains different levels due to the crystal field, such as $^4T_{1g}$, $^4T_{2g}$ and $^4A_{2g}$. Can anyone tell me what exactly ...
-2
votes
0
answers
60
views
Why do some elements exhibit variable valency?
I searched across the internet and the only answers I found were that it is due to the inert pair effect or due to energy difference between orbitals. Now since Auf-Bau principle is used to write the ...
-3
votes
1
answer
53
views
How does the concept of the electron shell (also called energy level) and the orbital coexist? [closed]
Running into a bit of confusion trying to understand the atomic structure and the root cause is mostly related to orbitals and energy levels.
At a basic level, I was taught that electrons orbit the ...
- 5
-3
votes
1
answer
40
views
Choosing energy levels for finding quantum numbers
When an element has multiple energy levels (i.e Titanium has $(Ar)3d^24s^2$), what energy level do we use to find the quantum numbers? Is it generally assumed the LAST energy level is used? or is it ...
3
votes
1
answer
416
views
If charge is quantised, how can It delocalize?
As I was trying to understand resonance, I got to know that it was imaginary phenomenon and it is just a tool to explain mechanisms and structures that are unexplained by Lewis dot structures or ...
- 177
-1
votes
1
answer
94
views
Convergence limit of emission spectra for atoms with multiple electrons
In high school chemistry, students are taught that the convergence limit in the emission spectrum of an element can be used to determine the first ionization energy.
However, what about the second, ...
- 249
4
votes
1
answer
264
views
Eigenfunctions of total angular momenta as linear combinations of Slater-determinants
In the Hartree scheme for many-electron atoms, the approximated Hamiltonian (in a.u.)
$$\hat{H} = \sum_{i=1}^Z \left(-\frac{1}{2} \nabla_i^2 -\frac{Z}{r_i} + V_\text{H}\left(r_i\right)\right)$$
is ...
- 41
-2
votes
1
answer
127
views
Graph of kinetic energy of ejected electron vs intensity
While studying photoelectric effect I got a doubt in the graph of kinetic energy of ejected electron vs the intensity of electromagnetic radiation.
Everywhere this graph is given as
But here for 0 ...
- 35
5
votes
1
answer
83
views
Atomic terms and perturbation theory
I have a question about the derivation of the possible atomic terms of an atom. Consider an atom with $N$ electrons in the central-field approximation, with hamiltonian
$$
H_{0} = \sum_{i=1}^{N} \left[...
- 477
2
votes
0
answers
65
views
Stark and Zeeman effects and their causes
In high school we are taught that Zeeman and Stark effect directly lead to the findings of further divisions of an electron's shell in an atom.
What is exactly the reason that causes the spectral ...
- 97
1
vote
1
answer
126
views
Why hot iron turns from red to white and then blue? [closed]
While reading structure of atom chapter no. 2 from ncert class 11th chemistry part 1 book, I got a doubt. In the book it says on page 40 that:
Hot objects emit electromagnetic radiations over a wide ...
- 35
2
votes
3
answers
320
views
Distance of Orbitals from Nucleus relation with Energy level and penetration power
I have studied that according to Aufbau rule the energy of subshells is dependent on the sum of $ n $ and $l$ values. This would imply that the energy of subshells in a shell varies as
$$ ns \lt np \...
- 23
-2
votes
1
answer
72
views
Can't the wavelength of an electron increase or decrease to "fit" the wave perfectly in any radius?
I was reading about how de Broglie's electron-wave theory explained the quantisation of energy in a Bohr atom. What I understand is as follows:
If the wave is to be arranged in the form of a circle ...
- 91
0
votes
1
answer
128
views
Are there compounds distance functions to define a compounds space metrics
Is there exist something like a distance function for compounds, computing a number for any two given molecules? Such a function would measure dissimilarity at the atomic structure and bonds levels, ...
- 195
0
votes
0
answers
59
views
Can someone elaborate what it means when its said that electron shells do not exist in multi electron systems?
I'm an undergraduate student in chemistry. I'm trying to grapple with all the new stuff we're learning and making sense of it. Now I want to know if electron shells really "exist" in multi ...
- 29
1
vote
1
answer
145
views
Why are orbits shown out of plane in popular cartoons of atomic structure? [closed]
The (former) U.S. Atomic Energy Commission had a seal showing a symbolic view of the atom that is unrealistic but instantly recognizable:
Source: https://blog.nuclearsecrecy.com/2012/04/13/friday-...
- 39.2k
0
votes
1
answer
266
views
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
- 19
2
votes
1
answer
197
views
Is there a difference between Hartree-Fock method and LCAO?
I have to dive in some quantum chemistry for a quantum machine learning project and I came across the so-called Hartree-Fock method.
In one of the reference I used, they considered electrons as ...
- 39
-2
votes
2
answers
347
views
What is the difference between alloying and doping? [closed]
When compared to doping, how is alloying different? What modifications to the structure are brought about by both of these?
-2
votes
1
answer
111
views
How can Planck’s equation and the wave equation simultaneously coexist with contradicting each other? [closed]
The equations:
E=hf (Planck’s equation, where E is the energy, h is the Planck’s constant and f is the frequency) and
V=fλ (where v is the speed (in a vacuum), f is frequency and λ is the wavelength) ...
- 352
1
vote
1
answer
69
views
How does bond formation affect the energetics of the bond?
I am an 11th grade student who has just started learning about bonds in compounds. My question pertains to a line written in JD Lee's Concise Inorganic Chemistry for JEE (Main and Advanced)
It was ...
- 29
-2
votes
2
answers
525
views
Why silicon doesn't have the electronic configuration [Ne] 3s¹ 3p³?
I have read that half or fully filled orbitals provide more stability to the element due to symmetry and exchange energy.It is the reason for electronic configuration of Cr-[Ar]4s¹3d⁵.
Then, why doesn'...
- 1
-4
votes
1
answer
513
views
What Are Angular Nodes , Radial Nodes, Nodal Plane and Nodal Surfaces? [duplicate]
Actually, i am confused between all of them. some says that angular node is same as nodal planes and radial nodes is same as nodal surfaces... and what's the difference between nodal planes and nodal ...
-2
votes
1
answer
73
views
Electrons in Bohr's atomic model [duplicate]
Why electrons don't fall into the nucleus in bohr's atomic model?
Is there a reason or explanation or is just a consideration?
user126889
1
vote
1
answer
142
views
Why the electronic configuration of samarium is ending with 4f⁶6s²
What is coming in my mind is that 4f^7 6s^1 should be more stable as it allows two orbitals to be half filled rather than 4f^6 6s^2 in which only one orbital is completely filled....can someone please ...
- 73
1
vote
0
answers
102
views
Why is it impossible to determine number of visible emission spectrum of He+
We know that atoms emit spectral lines on excitation and de excitation.
I was doing one high school question based on this theory
Number of visible lines when an electron returns from 5th orbit upto ...
- 19
3
votes
2
answers
193
views
Why is radial probability density exactly zero at the center?
I have read that the radial probability density is exactly zero at $r = 0$ because the radial probability density is
$$P(r) = \psi^2\,\mathrm dv,\tag{1}$$
where $\mathrm dv$ is the volume of spherical ...
- 53
1
vote
0
answers
24
views
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 ...
- 1,077
0
votes
2
answers
237
views
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 ...
- 11
-3
votes
1
answer
231
views
Which quantum numbers does the orbital angular momentum depend on? [closed]
I learned from a question that I recently solved that the orbital angular momentum depends on both the azimuthal and magnetic quantum numbers.
I did not expect this because the formula for the orbital ...
user125086
4
votes
1
answer
428
views
Excitation of hydrogen atom
I studied the Bohr's model of atom that says electron can jump to higher energy level by absorbing photon, but the quantum model says we have more than that (quantum numbers). Therefore, when the ...
- 61
4
votes
1
answer
458
views
Huge variation of the atomic size of Uranium
I've already posted this question in Physics Stack Exchange, but the answer that I received (actinide contraction similar to lanthanide contraction) is not convincing for me, or at least is not ...
- 534
0
votes
0
answers
77
views
A question regarding hydrogen emission and absorption spectrum
I have read in many articles as well as my textbook that when an electric discharge is passed through a sample of hydrogen gas it excites the electrons and glows emitting light.When this light is ...
- 51
2
votes
1
answer
367
views
Explanation of the missing 1-s orbital electrons of carbon in the molecular orbital diagram of methane
Consider the molecular orbital diagram of methane, for example found here:
I would like to know what happens with the two 1s orbital electrons of carbon in the molecular orbitals it is forming. Is it ...
- 199
-2
votes
1
answer
771
views
Comparison between Atomic Spectrum of Hydrogen and Alkali Metals
I posted a question on Chemistry Stack Exchange a while back. It was related to the naming of atomic orbitals. One of the answers to it mentioned a research experiment. The link to the question is ...
- 45
1
vote
2
answers
149
views
Size of Orbitals, Making Intuitive Sense of Quantum Model, Nomenclature of Subshells in the Quantum Model
Alright, so I am doing the Quantum Mechanical (or what some people call the Wave Mechanical model) of an atom. There's this part where we have different zones of the probablity of finding electrons, ...
- 45
9
votes
2
answers
2k
views
How to find the orbital a given wavefunction represents?
We were given the following question in chemistry class (under the topic “Atomic Structure”):
Which orbital does the following wavefunction represent? $$φ(r) = \frac{1}{81(6π)^{1/2}}\left(\frac{Z}{a}\...
- 133
1
vote
0
answers
46
views
Ambiguity on determining a relativistic Dirac orbital's "shape" when it has two angular components
Wikipedia says that a relativistic Dirac atomic orbital is a 4-component vector, with two angular parts and two spin parts. It also says, indirectly, that 'the top two components of a 2p(1/2) orbital ...
- 717
0
votes
0
answers
80
views
How are the energies of, e.g. the 4p orbitals of the first transition series, determined?
Take a first row transition metal, say manganese. The 4s and 3d orbitals are occupied in Mn; each orbital's energy can can be definitely determined by ionising that orbital, obtaining the resulting Mn+...
- 717
2
votes
2
answers
887
views
Why are higher-energy orbitals larger in size/radius?
I know the different atomic orbitals of atoms are derived from the wave function in the Schroedinger equation. Because I'm not a mathematician, though, I can't decipher the Schroedinger equation and ...
- 135
4
votes
1
answer
462
views
How do the odd proton-number elements originate?
I have a question about the origin of the odd proton-number elements in the periodic table, please.
As it is generally thought that the big bang produces hydrogen first, and then hydrogen combined to ...
user120456
0
votes
1
answer
3k
views
How do we write spin multiplicity for Mn(2+), Mn(7+)?
Mn has atomic number = 25
Since it is an exception to electronic configuration , unlike having = $\mathrm{3d^7}$ , it has electronic configuration = $\mathrm{3d^5,4s^2}$.
Formula for spin multiplicity ...
- 49
1
vote
1
answer
58
views
What kind of electronic configurations are possible?
Let us take $d^6$ orbital as an example:
A) ↑ | ↑ | ↑ ↓ | ↑ | ↑ |
Now , this one 1 way. My Q is that how is it possible that in the 3rd box , we have a paired electron but not in the 1st one. Like it ...
- 49
2
votes
0
answers
184
views
What will the correct value of spin quantum number for last electron of Na+ ion?
Electronic configuration of $Na^+$ ion is $1s^2,2s^2,2p^6,3s^0$.
I have noticed usually , we take spin quantum number as +1/2 first & then -1/2.
So , like for the above Q:It is for first 3e=+1/2 &...
- 49
2
votes
1
answer
124
views
Average distance of 1s electron from nucleus in He⁺ ion
What would be the average value of $r$, i.e. $\langle r\rangle$, in the $\mathrm{1s}$ orbital of $\ce{He+}?$
$$
\text{a}.~\frac{3}{2}a_0 \qquad
\text{b}.~\frac{3}{4}a_0 \qquad
\text{c}.~3a_0 \qquad
...
- 23
3
votes
2
answers
146
views
When people say "The energy of an orbital depends on its ℓ value due to screening effect" , what is screening what?
My book says:
Both the attractive and repulsive
interactions depend upon the shell and shape
of the orbital in which the electron is present.
For example electrons present in spherical
shaped, s ...
- 215
3
votes
0
answers
75
views
Energy levels of carbon and selection rules
Here is an atomic physics problem I am trying to solve:
The carbon ground state is $[He](2s)^2(2p)^2$. Suppose to excite an electron to the configuration $[He](2s)^2(2p)(3s)$. The spectroscopic terms ...
- 149
2
votes
2
answers
534
views
Why are the relative masses of isotopes not close to whole numbers?
Understandably, the relative atomic masses of isotopes are often not close to whole numbers as they're adjusted for isotope abudandancy eg. $A_r(Cl)\approx35.45$. However, wouldn't one expect the ...
- 181
1
vote
0
answers
61
views
What happens inside the orbital when energy provided to electron is not sufficient for it to change orbitals? [closed]
While studying the chapter called Atomic Structure, we were introduced with Bohr's model of an Atom. Even though not all of his postulates were right, I believe some were. A doubt arose in the ...
- 101
1
vote
0
answers
41
views
Do degenerate states have exchange energy?
I have read that exchange energy exists between non-degenerate levels $1s$ and $2s$ or between $1s$ and $2p_x$ in the Helium atom in the first excited level:
$$K_s = \left< 1s(1)2s(2)|H'|1s(2)2s(1) ...
- 395