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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69 views

Determining electronic configuration

One writes the electronic configuration in terms of shells, spdf subshells, orbitals, and spin of electrons. There are exceptions to principles we know. How does one confirm that the way of writing is ...
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1answer
30 views

Reason for same frequency of spectral line in infrared and visible region

I encountered this question while trying to understand the basics of spectroscopy and atomic structure. Which electronic transition in Balmer series of hydrogen atom has same frequency as that of n=6 ...
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2answers
96 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? ...
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1answer
48 views

Quantum mechanics electron probability [closed]

Schrödinger's equation yields us the solutions of 90% probability of presence of electrons in orbitals. Hence, the electrons in theory should be able to exist elsewhere in space as well. In that case, ...
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2answers
56 views

Azimuthal Quantum Number and Magnetic Quantum Number

I know that azimuthal quantum numbers and magnetic quantum numbers are used to find the no. of and the orientation of subshells respectively, but why do they have to be called so? I reckon that ...
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1answer
39 views

Lanthanum Electronic Configuration [duplicate]

Lanthanum has electronic configuration [$\ce{Xe}$] $4\mathrm{f}^0$ $5\mathrm{d}^1$ $6\mathrm{s}^2$. Why is the $4\mathrm f$ sub-shell not filled even though we know that $4\mathrm f$ is filled before $...
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2answers
394 views

What does Brightness/ intensity of spectral lines depend on?

My book states that it depends upon "The number of photons of same frequency or wavelength ABSORBED or EMITTED" From what I understood, if many hydrogen atoms within the discharge tube EMIT the same ...
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1answer
73 views

Is Na$^+$ more stable than Na? [duplicate]

I had a question in my textbook:- Na -> Na$^+$ + e$^-$ Cl + e$^-$ -> Cl$^-$ But Na$^+$ and Cl$^-$ have a stable electronic configuration. So, why do they react to form NaCl? So, this is my ...
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2answers
58 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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1answer
47 views

Are atomic mass unit (amu), unified mass unit (u) and Dalton (Da) the same unit but with different names? [duplicate]

I recently read up on some chemistry and found these units of mass: atomic mass unit (amu) unified atomic mass unit (u) Dalton (Da) Are they all the same unit but just with different names or are ...
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1answer
67 views

Is the given statement regarding Radial Probability Distribution Function correct or not?

Radial Distribution Function $(4πr^2R^2(r))$ gives the probability of the electron being present at a distance $r$ from the nucleus. Answer: The given statement is correct. My Query: According to me, ...
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1answer
110 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. ...
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1answer
35 views

Atomic shielding 2s to 1s

How much is the effecting shielding of the 1s electrons from the 2s electrons? . Because the 2s subshell overlaps with the 1s subshell this will cause the 1s electrons to 'feel' less charge than the ...
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20 views

Why does the oxides that form change down the alkali metals? [duplicate]

Why does Li2O primarily form when Li has reacted with O2 but the Na2O2 forms for sodium? Moreover, the primary product for the other alkali metals are superoxides instead of oxides and peroxides. How ...
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3answers
69 views

$\psi$ Represents amplitude of electron wave and $\psi^2$ represents electron density in a given space. How?

The $\psi$ represents amplitude of electron wave. So it's dimension should be $\left[L\right] $. But $\psi^2$ represents density of electrons in a given space. So it's dimension should be $\left[ML^{-...
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0answers
49 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 ...
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1answer
139 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 ...
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1answer
167 views

Maximum number of atoms in the ground state

I was given the following question. A sample contains $100$ identical and hypothetical $H$-like atoms ( $Z$ may be fractional). Out of the given atoms, some are in the ground state, while others are ...
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1answer
50 views

absorption spectrum of hydrogen atom [closed]

In absorption spectrum of hydrogen atom, only one electron is present in its one atom which is in ground state, so it means that all electrons can only absorb energy of photon of wavelength which lies ...
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1answer
832 views

Radial Probability Distribution Curve versus ψ² versus r curve for 1s orbitals

My question is basic, but I have already referred to a couple of books. This is an excerpt from Linus Pauling's book: the most probable distance of the electron from the nucleus, which is the ...
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2answers
61 views

Why is atomic orbital one electron wave function? Why distance from centre is proportional to angular wave function?

Consider the following statements: An atomic orbital is one electron wave function $\psi(r,\theta,\varphi)$ obtained from the solution to the Schrödinger equation. There two electrons in an atomic ...
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2answers
293 views

Strong or weak force between protons and neutrons?

I had learned that what keeps the protons and neutrons bound is the strong force and the weak force has to do with radioactive decay. but today I read an article from Science Daily that contradicts ...
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1answer
117 views

Magnetic moment of trivalent lanthanide cations

The effective magnetic moment $\mu_{\mathrm{eff}}$ of tripositive rare earth elements, is calculated by $$\mu_{\mathrm{eff}}=g_J\sqrt{J(J+1)}\mu_\mathrm{B}$$ Why can't we use normal formula as $\sqrt{...
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1answer
54 views

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 ...
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1answer
24 views

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?
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1answer
48 views

Angular Momentum of an orbital and orbit [closed]

While pursuing forth in Atomic Structure, I encountered the following concepts... According to Bohr, the angular momentum of an orbit remains quantized, i.e $\displaystyle mvr = n\hbar .$ But he ...
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1answer
51 views

What element did Rutherford use to obtain alpha particles in his experiment of gold foil? [closed]

What element did Rutherford use to obtain alpha particles in his experiment of gold foil?
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2answers
620 views

Why is fluorine a oxidising agent?

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 ...
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1answer
30 views

Conversion factor for chemical to physical scale of atomic masses

Before the 1960s chemists and physicists used to have different atomic mass tables. The main difference was that the physicists assigned the $^{16}$O as the O=16 from mass spectrometry. Chemists on ...
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63 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 $...
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46 views

Ratio of Total energy to Kinetic energy in hydrogen atom when the reference is changed

If in the hydrogen atom Potential Energy at $\infty$ is chosen to be $13.6$eV then the ratio of total energy and kinetic energy (with the sign) for $1$st Bohr Orbit is? My Attempt I just simply gave ...
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1answer
57 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 ...
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243 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 ...
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50 views

Term symbols for excited nitrogen (2s2p^4 configuration)

Looking at the NIST levels listing for neutral nitrogen atom, one of the excited configuration is $2s2p^4$ configuration. https://physics.nist.gov/cgi-bin/ASD/energy1.pl?encodedlist=XXT2&de=0&...
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1answer
28 views

Can you determine when the orbtials of an atom will hybridize?

We know that when it comes to C its orbitals hybridize (they become sp3 , sp2 or sp) and the energy levels of an hybridized orbital of this kind is lower than that of the p orbital that formed it but ...
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53 views

Why does ψ^2 ( square of orbital wave function ψ) give the probability of an electron in a given region? [duplicate]

Today I was introduced to the Orbital Wave Function for electrons. $\Psi$ is a mathematical function for coordinate of electrons and has no physical meaning. But $\Psi^2$ gives probability of an ...
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143 views

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 ...
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1answer
385 views

Electron pairing in atoms

A question asks: This question refers to isolated gaseous atoms. In which atom are all electrons paired? Ba, Br, S or Si? I thought it was Ba as its electron configuration is [Xe] 6s2. However, ...
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26 views

Does it exist a transgression to Hund's rule of maximum multiplicity principle in this given electron box notation?

The following question arises from a set of statements from which I'm asked to state whether they are true or false. This is as follows: Indicate which of the following statements are true or ...
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2answers
121 views

Effective nuclear charge and electron repulsion

To the best of my knowledge, the effective nuclear charge $Z_\mathrm{eff}$ is usually defined such that the potential energy of an electron in an atom, $\langle V \rangle$, can be expressed as $$\...
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0answers
104 views

Why is there a big jump in first ionisation energy between sodium and potassium?

I know the trend in group 1 is that ionisation energy decreases down the group due to an increase in atomic radius and more energy levels are added so more shielding, but I'm not sure why there's such ...
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1answer
290 views

What is more stable, Na+ or Na? [closed]

As per noble gas configuration $\ce{Na+}$ should be more stable than $\ce{Na}$. But at the same time $\ce{Na+}$ has a positive charge so it will be easily attracted by negative charge while $\ce{Na}$ ...
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1answer
184 views

Atomic Orbital and Wave Function

I was reading about the atomic orbital in my chemistry textbook. It says that the atomic orbital (psi) is a mathematical wave function that depends on the coordinates of the electron. It is also ...
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1answer
47 views

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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Why $ns^2np^6$configuration so stable? [duplicate]

In my chemistry textbook it is said that noble gases have stable configuration because they have achieved the maximum outermost shell configuration, which corresponds to the $ns^2np^6$ configuration. ...
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1answer
72 views

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 ...
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3answers
321 views

Photoelectric effect (AP Chemistry question)

Which of the following postulates regarding the photoelectric effect is considered to be INCORRECT according to the quantum mechanical model we currently understand? (A) Increasing the intensity of ...
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2answers
255 views

Why is atomic number unique? [closed]

We all know that atomic number of an atom is "unique" just like fingerprint. And no two elements can have same atomic number. But how can we be So sure that no two elements can have same atomic number?...
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1answer
208 views

Diamagnetic vs Paramagnetic

As far as I know, to know whether a substance is paramagnetic or diamagnetic, we check if that particular species has got unpaired electron or not. But my textbook lists- Examples of Diamagnetic ...
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1answer
218 views

To move one electron in one H atom from the ground state to the second excited state, 12.084 eV are needed

How much energy is needed to cause 1 mole of H atoms to undergo this transition Assume Bohr's model of quantisation The energy for transition is $$1312\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)$$ ...