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])

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Do electrons have some volume, area or shape?

I am in 8th grade now and when I was in 6th grade, my science book had diagrams of the electronic configuration of atoms. The electrons were round like spherical balls. Is it true that the electrons ...
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What is d-orbital collapse?

When I was perusing the works of Schwarz on atomic structure, I came across the unfamiliar term of d-orbital collapse. He describes it as a variation in energetic sequence from group 1 to 3 elements ...
C. WJ's user avatar
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1 answer
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Why does hydrogen burn with a pale blue flame while its emission spectral lines are red in colour?

I was studying oxidising flames and realized that sodium burns with a bright yellow flame the wavelength of which is around 588 nm. Then I searched for emission spectra of sodium and found that the ...
Eclipse239's user avatar
11 votes
1 answer
2k views

Cause of uniform glow in cathode ray tubes

I got the following extract from a chemistry book (emphasis mine): It is observed that current does not flow through the gas at ordinary pressure even at high voltage of 5000 volts. When the ...
M Shehzad's user avatar
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10 votes
2 answers
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Terminology of atomic spectroscopy: Difference Among Term, States and Level

In A Primer on Quantum Numbers and Spectroscopic Notation Contents, the concept of a term and level is described as a) The level is the set of 2J+1 states with specific values of L, S, and J. ...
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9 votes
2 answers
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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}\...
Aaryan's user avatar
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9 votes
1 answer
3k views

What is the exact definition of the radial distribution function?

I have been very confused by the radial distribution function which is often used in chemistry to predict the probability of finding an electron at a distance from the nucleus. From Atkins' Physical ...
S R Maiti's user avatar
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8 votes
1 answer
355 views

Empirical Evidence and Assignment of Orbital Energies (Electron Filling)

I see a lot of questions on electron configurations from students at various levels here. Students mechanically remember how to fill orbitals and sorry to say many teachers do the same. Not a single ...
AChem's user avatar
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7 votes
1 answer
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How does de Broglie actually prove Bohr's postulates?

We know Bohr said that the angular momentum of an electron is an integral multiple of $nh/(2π).$ And in de Broglie's wave equation, he said the circumference of the path of the electron traveling as a ...
user81201's user avatar
7 votes
2 answers
1k views

How is the potential energy between two atoms measured?

In class, we learned about the interatomic potential graph. How does one actually measure the potential energy between two atoms experimentally to ensure the graph is correct? What device is used?
robert kiligan's user avatar
7 votes
1 answer
383 views

Why does exchange integral 1s2p not vanish for Helium excited state?

I am studying first-order perturbation theory applied to the first excited state of Helium. I am facing the following problem: I understand that the Coulomb integral for all 2p functions will not be $...
Vinícius's user avatar
6 votes
2 answers
2k views

Why is potassium less dense than sodium?

Potassium has a density of $\pu{0.86g/cm3}$ and sodium has a density of $\pu{0.97g/cm3}$,even though potassium is below sodium and one might expect the alkali metals to exhibit monotonously increasing ...
Bruh Moments's user avatar
6 votes
1 answer
176 views

Basics of wave-mechanical model of atom

Why is it that for the $\mathrm{d}$ subshell we have $\ \ \mathrm{d}_{xy}, \ \ \mathrm{d}_{yz}, \ \ \mathrm{d}_{xz}, \ \ \mathrm{d}_{x^{2}-y^{2}},$ and $\mathrm{d}_{z^{2}}$ orbitals only? Why aren't ...
Gurjot Singh's user avatar
6 votes
2 answers
919 views

Why is there an orbital angular momentum if the electron isn't properly revolving around the nucleus?

I'm a tenth grader who's just been introduced to this subject of atomic structure, so please help. I recently read that an electron doesn't have circular motion around a nucleus, its motion is kind ...
Plusminus 's user avatar
5 votes
1 answer
1k views

Why is it that protons and electrons undergo the same amount of deflection in an electric field if they have the same energy?

The question I have is with respect to this diagram. Which depicts a stream of protons and electrons entering a proton field with equal energy. Why is it that in the case where the energy of protons ...
user avatar
5 votes
1 answer
678 views

What happens to the first ionization potential when a hydrogen-like atom captures a particle?

This is a textbook problem from Resonance DLPD Physical Chemistry, Page #83: The mass of a proton is $1836$ times the mass of an electron. If a subatomic particle of mass $207$ times the mass of an ...
user69284's user avatar
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5 votes
1 answer
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Could a positron be made to stably orbit an atom? [closed]

Suppose you have a single atom of neon, argon or some other noble gas of your choice. While the entire atom is electrically neutral a nearby positron would probably be more strongly attracted to the ...
Sidharth Ghoshal's user avatar
5 votes
1 answer
246 views

Why the term 'unified' in "unified mass unit"? [closed]

Why different unit symbols - amu, u and dalton are used for representing atomic mass? And what does the term 'unified' mean in "unified mass unit"? Thank you.
Pradhuman Sharma's user avatar
5 votes
1 answer
416 views

Who came up with the box and arrow diagrams for electron configurations?

In general chemistry texts, the electron configurations are sometimes shown in boxes with up and down arrows to show the concept of paired spins. My impression for years was that Hund used such ...
AChem's user avatar
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5 votes
1 answer
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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[...
AlfredV's user avatar
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1 answer
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Notation in atomic structure

In the book, The theory of atomic structure and spectra, Robert D. Cowan says that the allowed terms of $p^2$ are $^1S$, $^1D$, $^3P$ and so the possible terms of $p^2 + p\quad$ (obtained by using the ...
amilton moreira's user avatar
5 votes
1 answer
438 views

Are Slater’s rule and lanthanide contraction contradictory?

According to most textbook and the Wikipedia page of lanthanide contraction, the phenomenon is due to poor shielding of nuclear charge by 4f electrons. However, the σ value of 4f electrons to 6s is 1....
HFerKerman's user avatar
4 votes
3 answers
944 views

Does electron mass decrease when it changes its orbit?

I have studied this in my chapter atomic structure that when an electron changes its orbit from lower energy to higher energy state , it does not state in my book that it moves there but that it ...
Srijan's user avatar
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4 votes
1 answer
435 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 ...
Zhentian's user avatar
4 votes
1 answer
464 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 ...
gryphys's user avatar
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4 votes
2 answers
2k views

The true shape of p orbitals

I'm trying to model $\mathrm{p}$ orbitals using a 3D program. What confuses me is that there are 2 shapes of $\mathrm{p}$ orbitals. I'm not sure which one is the accurate model. And what is the ...
Fast Snail's user avatar
4 votes
1 answer
611 views

Lother Mayer curve

While studying about atomic trends, I encountered the Lothar Meyer curve: If the covalent radius decreases across a period, why is the graph of atomic volume reaching local minima halfway in the ...
Shub's user avatar
  • 408
4 votes
1 answer
4k views

In Bohr's model what is angular momentum in the lowest orbital?

Angular momentum is given by: $n\frac{h}{2\pi}$ where $n=1,2,3...$ And angular momentum is also given by: $\sqrt{l(l+1)}\frac{h}{2\pi}$ By the first equation angular momentum should be $\frac{h}{2\...
user avatar
4 votes
1 answer
736 views

Flame Test of Alkali Metals and Alkaline Earth Metals

The flame test colors for alkali metal and alkaline earth metal salts are well known, but what about the metals themselves? Do they also give rise to the same colors (eg, brick red for Ca, pale green ...
Buckbitter Inning's user avatar
4 votes
1 answer
358 views

How do we get g and E values for various levels to calculate electronic partition function

When we calculate electronic partition function using the formula: $$q_\mathrm{elec}=\sum^\infty_{n=1}g_ne^{-E_n/k_BT}$$ How can I get the $g_n$ value and $E_n$ values for $n=0,1,2,3...$ levels? I ...
Fast Alex's user avatar
4 votes
2 answers
2k views

Why did J.J. Thomson observe protons in his cathode ray experiment?

In this MIT lecture, at 7:22, the professor says that when J.J. Thomson added a positively charged plate on one side of the cathode ray and a negatively charged plate on the other side, he observed a ...
Michael Chu's user avatar
4 votes
2 answers
8k views

How do we find the angular, radial nodes and the quantum numbers when the radial probability distribution curve's equation is given?

I am having serious conceptual issues with the Schrödinger equations. Please note that I only have basic school level (11th grade) knowledge of these equations and we are expected to know very little ...
brainst's user avatar
  • 177
4 votes
1 answer
505 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 ...
user avatar
4 votes
1 answer
87 views

Practical to measure topography of a large area (mm-scale) with scanning probe microscopy (SPM)?

I'm currently very new to nanotechnology. I do understand that it is possible to achieve an excellent topography image of a sample by SPM. However, is it possible to do SPM over a large area (for ...
Kanthee Kosolyuthasarn's user avatar
4 votes
1 answer
533 views

Electronic configuration of the actinides

I was reading about actinides and I need some help in understanding this paragraph from Concise Inorganic Chemistry by JD Lee - The electronic structures of the actinides do not follow the simple ...
Anubhab Das's user avatar
4 votes
2 answers
2k views

Why is fluorine a oxidising agent? [closed]

An oxidizing agent pulls the electron cloud of the substance being oxidized towards itself, for example: $$\ce{F2 + 2 X- -> 2F- + X2}\qquad (\ce{X} = \ce{Cl}, \ce{Br}, \ce{I})$$ We also know that ...
Chemist's user avatar
  • 531
4 votes
1 answer
1k views

Volume of orbitals

As I was learning about atomic structure, the lecturer made a seemingly dubious claim: The volume of a p orbital is one-third that of the s orbital. Thus, inter-electronic repulsions are ...
Tan Yong Boon's user avatar
4 votes
1 answer
856 views

Angular momentum of an electron in an atom

The Orbital Angular momentum of an electron in an atom is given by $\hbar \sqrt{l(l+1)}$ and the Spin Angular Momentum is $\hbar \sqrt{s(s+1)}$. So what is the resultant Angular momentum of an ...
Ankit Kumar Misra's user avatar
4 votes
1 answer
269 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 ...
Simone's user avatar
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4 votes
0 answers
692 views

Did JJ Thomson know about Eugen Goldstein’s experiment discovering canal rays?

We learn that JJ Thomson discovered the electron in 1897. Several years EARLIER in 1886, Eugen Goldstein performs the same experiment but with the anode and cathode switched to produce positively ...
suse's user avatar
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4 votes
0 answers
2k views

Why Rutherford was shocked by results of gold foil experiment?

The way Rutherford's classic gold foil experiment has been presented (including by Rutherford himself) doesn't make sense to me. As many of you know, Rutherford famously described himself as being ...
theorist's user avatar
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3 votes
3 answers
6k 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 ...
user avatar
3 votes
2 answers
1k views

Why do subshells and orbitals exist? [closed]

I'm just a curious high school student. Sorry if this sounds dumb. How exactly did the concept of atomic subshells and orbitals come about? And why exactly are there n-1 subshells and 2l+1 orbitals? ...
StackExchange_User_4's user avatar
3 votes
3 answers
378 views

Bohr's model of an atom

This question is not very mighty. But I'm having a problem wrapping my head around the Bohr's atomic structure. The textbook says electrons revolve around the nucleus in fixed energy shells, with each ...
user231094's user avatar
3 votes
1 answer
424 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 ...
Dheeraj Gujrathi's user avatar
3 votes
2 answers
131 views

Atomic weight = expected weight?

The atomic weight of an element, is it accurate to say that another way to think of it is the expected value of that element's weight if we were to sample one at random from the environment? Are man-...
AJJ's user avatar
  • 197
3 votes
2 answers
1k views

For hydrogen like atom, find velocity from potential energy

PE of system is given by $$\mathrm{U(r) = \frac{-Ke²}{r^3}}$$ assume bohr model to be valid Find velocity For this I used $\mathrm{\frac{-PE}{2} =KE}$ and then used $$\frac{mv^2}{2} =\frac{Ke^2}{2r^3}...
user60302's user avatar
3 votes
1 answer
742 views

Do electrons of opposite spin attract each other? [closed]

Electrons of opposite spin create magnetic fields that are opposite to each other. So, is it possible that, 'such electron pairs attract each other' or ' they distract each other less than electron of ...
tara's user avatar
  • 41
3 votes
1 answer
419 views

How did Thomson calculate the momentum of electron when he didn't know the mass of electron?

This was proven in 1903 by J. J. Thomson who calculated that the momentum of the electrons hitting the paddle wheel would only be sufficient to turn the wheel one revolution per minute. source J. J. ...
Tushar's user avatar
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3 votes
2 answers
271 views

Restrictions on transitions in Spectroscopy

Just for the sake of an example, let's assume a transition from one energy state to a higher energy state in atomic absorption spectrum If the energy difference between the ground state and first ...
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