Questions tagged [atoms]

Smallest particle still characterizing a chemical element. It consists of a small nucleus charged positively, carrying almost all of the atom's mass, with electrons surrounding it. This tag should be applied to questions that specifically concern atoms or their properties. For the charged particles, please use [ions] instead. If your question is specifically about [protons], [neutrons], or [electrons], use those tags instead.

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261 views

DFT Calculations, Atomic Ionization Potentials -- Which Exchange-Correlation Functional to Use, to Preserve Koopmans Theorem?

I have a program which can perform density-functional calculations for atoms, given a density functional. Of course the simplest form of exchange potential to use is one relevant for a uniform ...
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461 views

Are the rules proposed by Slater for the calculation of effective Z right?

Today I studied Slater's rules for calculating the effective nuclear charge. One particular line, "The shielding power of the d and f orbital is lesser in comparison to the p and s orbitals",...
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How many electrons with l = 1 does Si in its ground state have?

I was solving practice problems for electron configuration and periodic table, and I got stuck through a question: An atom of silicon in its ground state has how many electrons with quantum number $...
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Whats the difference between ionization energy and orbital energy?

If you look at the trend in orbital energies as you go across a period the pattern is clear (orbital energy decreases with increasing effective nuclear charge) and, to my knowledge, it has no ...
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1answer
76 views

What reaction is expectable from the atomized reactants?

Let we have a reaction that starts from some reactants to produce some products. When the activation energy is provided to the reactants they will be atomized and produce a gas of individual atoms. ...
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1answer
911 views

Electron pairing and repulsion [duplicate]

If two electrons that get paired occupy the same orbital, then wouldn't there be a heavy amount of repulsion between the two? As is, since electrostatic force ${\displaystyle \propto }$ $\ce{ 1/ (...
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Is Dalton's Atomic Theory a theory or a postulate?

It is always mentioned that Dalton proposed an Atomic Theory. But when you read it, it consists of the following: The main points of Dalton’s atomic theory, an explanation of the structure of ...
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What are the physical manifestations of radial nodes?

I realize that nodes (both angular and radial) are areas with zero probablility of finding an electron. I realize that plotting the square of the radial eigenfunction for an orbital will give the ...
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2answers
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Why don't the electrons of opposite spins collide in an orbital?

As I was reading through my textbook, I got to know that in an orbital, there are 2 electrons of opposite spins. My question is: Shouldn't they collide whilst they are rotating?
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234 views

Different masses for the same element and isotope?

I am watching this Khan Academy video on mass defect and binding energy, it uses helium-4 as an example to go through the concept. The person finds the predicted mass (protons + neutrons) to be 4....
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Why is it easier to determine the radius of inert/noble gases?

My textbook says it is possible to determine the atomic radius of the inert gases like He, Ne, Ar etc because they roam freely and are incapable of forming bonds. However it is very difficult to find ...
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Are the energies of orbitals that are not filled in an atom, equal?

In a hydrogen atom only 1s orbital is filled. Does this mean that the energies of all other orbitals are equal? If so,why?
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In nuclear chemistry, how does a neutron split to form a proton and an electron?

I'm studying radioisotopes at the moment and balancing nuclear reactions isn't making sense in that more matter is coming out of the equation in negative β⁻ decay equations: $$\ce{_6^{14}C -> _7^{...
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111 views

Lother Mayer curve

While studying about atomic trends, I encountered the Lothar Meyer curve: Similar graph found on internet If the covalent radius decreases across a period, why is the graph of atomic volume ...
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What is 'space'? [closed]

What is in the space between atoms? I understand that molecules are constantly being formed from collisions and such, but what I do not understand, is, on a tiny level, within the level of the atom, ...
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Can you calculate the properties of a substance based solely on its atomic properties?

I'm trying to write some software that I can use to determine, roughly, what the physical properties of a pure substance are. I know I could just use a database of the known properties of each element,...
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747 views

Law of reciprocal proportion

Is it necessary that the valency of an element must have the same valency? For eg. If 2 elements A and B combine with the same mass of C, is it necessary that they will have the same valency as they ...
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673 views

Energy levels in non-hydrogen-like atoms

The energy $E_n$ for a hydrogen like atom is given as $$E_n = -hcR_\ce{H}\frac{Z^2}{n^2}$$ However, aside from on wikipedia where there is $$E_n = -hcR\frac{Z_\text{eff}^2}{n^2},$$ I can't find ...
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Why did the alpha-particles in Rutherford's experiment not collide with the electrons? [duplicate]

In Rutherford's experiment to show the existence of nucleus in an atom, the alpha-particles were exposed on the surface of certain metal i.e. gold. He observed that more than 99% of these particles ...
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1answer
12k views

Is there a relationship between an electron's energy and its distance from the nucleus?

I have read that in Bohr's model of the atom electrons in the same atomic orbital have the same energy, and that this energy (as a result of the electron existing in a fixed atomic orbital) is related ...
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1answer
2k views

Are orbitals always filled in from closest to nucleus to farthest away?

In which orbital, 4f or 6s, would an electron have a greater likelihood of being near the nucleus. I figured that the 6s would be closest, since it is filled in first when using the Aufbau principle. ...
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2answers
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Degeneracy of orbitals?

Why is that in an external magnetic field(uniform) the degeneracy of d,f orbitals is lost but the degeneracy of p orbitals remain intact if the main cause of losing degeneracy is the difference in ...
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1answer
152 views

While calculating the effective nuclear charge, why don't we consider effect of outer electrons on inner ones? [duplicate]

When calculating the effective nuclear charge for an electron, why do we only consider the repulsive effect of the inner electrons on the outer electrons? The outer electrons also repel the inner ones ...
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Does direction matter in breaking a bond?

Im not sure if this question belongs here or in another community. I was wondering if the direction that we apply a force in order to break a bond matters and how it affects strength. Say we have one ...
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Why do principal energy levels in an atom get closer together as n increases?

The title says it all. Reasons that I can supply include: increased nuclear charge increasingly catches up in terms of influence to the increasing shielding and proof by contradiction in that if the ...
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220 views

Ground state term symbol, why is $L = |M_L|$, if L must be a maximum?

I'm trying to understand how to predict ground state term symbol of atoms. After finding the biggest S, why the biggest L will be $L = |M_L|$, where $M_L = \sum m_l$? I know this rule works to ...
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How many atoms are represented in this equation?

$\ce{Pb(NO3)2 + 2KI -> PbI2 + 2KNO3}$ The answer says 26, but shouldn't it be 13? Because actually, the number of atoms involved in the reaction are 13, and once the reaction is completed, again, ...
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The mass of carbon atom [duplicate]

I was reading Silberberg's principles of general chemistry when I noticed that it says that the mass of carbon12 is exactly 12 amu. But when I calculated the total mass of its components (6 protons ...
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How to derive the electron density of Hooke's atom?

Hooke's atom has the following wave function: $$\Psi( \boldsymbol{r_1}, \boldsymbol{r_2}) \propto \left( 1 + \frac{|\boldsymbol{r_1} - \boldsymbol{r_2}|}{2} \right) \exp\left(-\frac{(r_1^2+r_2^2)}{4}\...
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Why are the d-orbitals so named? [duplicate]

Why are the $d$-orbitals so named? The naming of $p$-orbitals is fine. I can easily name any p orbital according to the axis along which it is oriented. But what about $d$- orbitals? Why are there ...
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4answers
1k views

In helium-2, would each electron experience a single positive charge from the nucleus?

If we have an atom of hydrogen-1, we know that there exists one proton with one electron and in helium-2 two protons with two electrons. My question is that do protons get shared equally with ...
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Schrödinger equation for multi-electron atoms

Does the Schrödinger equation alter its form when we apply it for an atom having a configuration other than hydrogen-like? I think it should happen because of difference in nuclear attraction and ...
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2answers
11k views

Does the Bohr model violate the uncertainty principle?

In a book, it is stated that one reason for the failure of Bohr's theory was the fact that it violates the uncertainty principle. Is this fact true? How so?
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Element with No Proton?

On seeing this graph closely I noticed the there a element with no proton. But with no proton there will be no electron too and don't think that an lone neutron would form an element. So is that given ...
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276 views

Atomic Orbitals

I read in a textbook that after an electron jumps to a higher energy level when supplied with high temperatures or current, they again fall back to their respective energy level by losing energy and ...
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1answer
14k views

How do scientists count the exact number of electrons, protons, neutrons in the atom? [duplicate]

An atom is very small so it is probably difficult to focus exactly on a single atom. I wonder how scientists count the exact number of electrons, protons, neutrons in an atom of a certain element. ...
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Why are atom spherical in shape ?

I am learning about structure of atom, in which i saw right from J.J. Thomsom atomic model to modern nuclear atomic model all are spherical in shape. I have seen how different discoveries help to ...
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1answer
595 views

If atoms are mostly empty space then how are we able to interact with things?

Note: This question has come out of curiosity Q: We all have read that atoms are mostly empty, they are generally compared to a football stadium in which a pea is kept in the center (nucleus) and ...
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1answer
1k views

How do we know the number of s and p orbitals in a shell?

How do we know how many s & p orbitals will be in a shell? There is one 2s orbital and three 2p orbitals in shell #2. There is one 3s orbital, three 3p orbitals and five 3d orbitals in shell #3....
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1answer
213 views

How are atoms manipulated?

I was wondering how scientists are able to handle atoms. They are very small, but surely people are able to interact with them somehow? The Large Hadron Collider is one example. Also, they try and ...
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1answer
6k views

Finding orbit radius using the Bohr model and Rydberg equation

To start with its a homework problem, quite lengthy. A particle of mass equal to 208 times the mass of an electron moves in a circular orbit around a nucleus of charge $+3e$. Assuming the Bohr ...
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682 views

Why don't alkaline earth metals lose only one electron when they are ionized?

Why doesn't alkaline earth metals lose only one electron when they are ionized ? I know that magnesium atoms like to have the electronic configuration of neon but I don't understand the reason that we ...
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1answer
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Types of radioactive decay

Besides alpha, beta, and gamma, are there any other types of radioactive decay? If so, what are they? Is there any type of radioactive decay that is more powerful than gamma?
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Calculating nearest neighbor distances

For cubic materials, there are equations in which to calculate nearest neighbor (NN), second nearest neighbor, etc. Can this be done with tetragonal crystal structures? I want to calculate NN, 2NN, ...
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1answer
651 views

Recoil velocity of atom when electron is excited

If an electron is excited from the $n = 1$ level to the $n = 2$ level in a hydrogen atom, how can we find the recoil velocity of the atom?
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Brackets in chemical formulas

When you have brackets such as $\ce{Zn(NO3)2}$, if there is a coefficient around the formula such as $\ce{2Zn(NO3)2}$, how would you read this? Would there be 2 zinc atoms, 4 nitrogen and 12 oxygen ...
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1answer
533 views

The proper explanation for the general formula of the DU? [duplicate]

I found a formula for the degree of unsaturation (DU) in Clayden’s Organic Chemistry. It explains, simply, the unsaturation with the difference in H atoms. Then I stumbled upon the general formula: $$...
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896 views

Bombarding atoms with electron gun?

Just to explain this question in a better way just think about the Rutherford's experiment(the alpha particle bombarded on Gold foil) be conducted using a electron gun in place of the Alpha one.. So ...
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1answer
226 views

Why is the ionic radius of hydride so large?

The order of ionic radii for halides and hydride is apparently as follows: $$\ce{F-} < \ce{Cl-} < \ce{Br-} < \ce{H-} < \ce{I-}$$ Why is the hydride ion so large, even larger than bromide ...
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1answer
76 views

Why do Rydberg atoms have electrons that can transition above the first ionization energy?

Why do Rydberg atoms have electrons that can transition above the first ionization energy? This can only happen in a multi-electron system but I don't see how the Rydberg formula would even work for n ...

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