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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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31 views

Effective nuclear charge and electron repulsion

To the best of my knowledge, the effective nuclear charge $Z_{eff}$ is usually defined such that the potential energy of an electron in an atom, $⟨V⟩$, can be expressed as $⟨V⟩= -Z_{eff}⟨ψ|\frac{1}{|...
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how is mass of nucleus in carbon-12 more than 12u [duplicate]

The mass of proton on atomic unit scale is 1.00727 amu. The mass of neutron on atomic unit scale is 1.00866 amu. Carbon-12 has 6 protons and 6 neutrons, right? So its atomic mass should be 12....
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33 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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how does the nucleus of an atom remains compact? [duplicate]

If the nucleus of an atom is stable and can’t be change by everyday chemical reaction. How does it keep itself compact if it is all positive and for example when an atom turns negative, what happened ...
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1answer
54 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
68 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
195 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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29 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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2answers
172 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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152 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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3answers
218 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 ...
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1answer
59 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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1answer
90 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 $$1312\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)$$ ...
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220 views

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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1answer
76 views

Do different oxidation states of the same element have the same emission spectrum?

I looked at the flames of copper (I) chloride and of copper (II) chloride through a spectroscope and they looked the same. The flame colour is the same too. But since they have different oxidation ...
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1answer
97 views

Molecular dynamics (Mac OSX user): what software can I use to plot RDFs for NPT simulations? VMD only works for NVT (constant volume)

I would be very grateful if someone could recommend a way to plot RDFs for NPT ensemble molecular dynamics simulation results. I use CP2K to run NVT simulations and usually use VMD to process ...
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1answer
161 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 ...
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28 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
74 views

Doubt in a question related to electronic transitions in Bohr's orbits

Question In Bohr series of lines of hydrogen spectrum, the third line from the red end corresponds to which one of the following inner-orbit jumps of the electron for Bohr orbits in an atom of ...
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1answer
52 views

Why potential energy is neglected in this problem for calculating the energy difference between two stationary Bohr Orbits? [closed]

Question An electron in a hydrogen like atom makes a transition from a state in which its de-Broglie wavelength is $\lambda_1$ to a state in which its de-Broglie wavelength is $\lambda_2$, then ...
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39 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." This is a ...
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45 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....
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1answer
114 views

Why does zinc sulfide glow when hit by electrons? [duplicate]

In cathode ray tube experiment in order to check the direction of flow of electrons a hole was made in a note and behind it phosphorescent material zinc sulfide it was coated. Why does zinc sulfide ...
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53 views

What will happen if electron as a wave undergo destructive interference while travelling in its Orbit?

Today I came across a justification of Bohr's angular momentum quantization using the De- Broglie's hypothesis. The justification said that since the electrons are having wave nature also then while ...
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2answers
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Finding atomic number given energies of emitted photons

A hydrogen-like atom (atomic number $Z$) is in a higher excited state of quantum number $n$. This excited atom can make a transition to the first excited state by successively emitting two photons of ...
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1answer
393 views

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 ...
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1answer
448 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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1answer
213 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.
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32 views

How did Planck reach the conclusion that energy comes in packets based on black body curves? [closed]

I understand that if wavelength continues to decrease energy emitted by an atom would get to infinite, but how does the max wavelength at a particular temperature translate to discrete energy packets. ...
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3answers
106 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 ...
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2answers
149 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
103 views

What is the unit of the Rydberg Constant? [duplicate]

In the image, the Rydberg constant seems to have two units. How is that possible?
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1answer
117 views

What are orbitals actually? [closed]

If s, p, d and f subshells have these kinds of boundary surface diagram, then why don't they include the probability of finding electrons in their preceding shells? As in, if d subshells have ...
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1answer
254 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 ...
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0answers
71 views

How can the potential energy at the infinite energy level in an atom be zero?

I have recently learnt about atomic structure and the Bohr model of the atom and have observed a discrepancy between it and my previous knowledge based on physics. For simplicity, assume the atom is ...
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31 views

Strongest overlap among s–s, p–p, s–p [duplicate]

So, I was wondering, when overlap of orbitals takes place, among s–s, s–p, p–p which type of overlapping is stronger? Because in s–s more volume is being used in overlap, but the electron density is ...
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2answers
435 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?
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262 views

Which principle goes against the concept of Bohr's fixed orbits? [closed]

Can you also state the principle which goes against it?
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1answer
121 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 ...
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1answer
209 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 ...
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1answer
50 views

Deducing the shell when transition occurs such that two photons are discharged

Find $n$ (quantum number) corresponding to the excited state of $\ce{He+}$ ion if on transition to ground state the ion emits two photons in succession with wavelengths $\pu{108.5 nm}$ and $\pu{30.4 ...
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1answer
217 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 ...
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1answer
50 views

Identifying orbital given electron probability density plot

Being a high-school student, I only have a qualitative understanding of the wave mechanical model of atom. Below are my inferences regarding the plot shown in the above picture: The concerned ...
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1answer
56 views

Does one atom of an element show the properties of a bulk of that element? [duplicate]

For example, does one atom of gold have a golden color?
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1answer
256 views

Why is a carbon to iodine pi-bond less stable than a carbon to fluorine pi-bond?

This question comes from a second semester undergraduate organic chemistry course. Please refer to the image below with regard to the question. My understanding of the trend in section 4a is that "...
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3answers
1k views

What are the possible magnetic quantum numbers of silver? [closed]

What are all the possible quantum numbers ml and ms of the electrons in the outermost s orbital of silver? I'm new to this concept. Can anyone walk me through this?
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2answers
435 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 ...
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1answer
110 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
241 views

Slope of Graph of Wave Number vs inverse square of the principal quantum number(1/n^2) in Hydrogen Emission spectrum

What is the final expression we get for wave number in a hydrogen emission spectrum? Let us say for example from 6 to an orbit $n$. Considering that it is an emission spectrum, I think it would be ...