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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How to make the Radius of an Atom Larger? [closed]

Let us say I take 1000 electrons into an atom. How much will it increase the radius of the Atom? Is there a formula I can use to determine this? Is it possible to insert an electron with a proton to ...
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Why is atomic mass unit/unified atomic mass defined against Carbon 12?

I have searched the web all over this question and I have not really found an answer to my satisfaction. From my understanding of the topic so far, I understand that reason why concept of unified ...
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When is the n+l rule followed when working with energy of different orbitals?

While going through my book, I came across a problem which gave some options about the order of energy of 3s, 3p and 3d orbitals of hydrogen atom. The correct answer was given as: 3s, 3p and 3d ...
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D block elements electronic configuration

We have found the electronic configuration of d block elements.As we move from left to right in the periodic table the energy of the 3d subshell is decreased and it becomes smaller than the energy of ...
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1answer
43 views

Atoms vs molecule when talking about the avogadro's number? [duplicate]

By far, my understanding is that a molecule is made up of atoms bonded together. For example, a molecule of water ($\ce{H2O}$) has 2 hydrogen atoms and one oxygen atom. However, when it comes to ...
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Why electrons do not distribute evenly among the atoms in a molecule? [closed]

I was wondering why the state where electrons are evenly (or the closest to being evenly) distributed among the atoms in a molecule is not the lowest energy state? For example, in a water molecule it ...
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37 views

Rutherford's Alpha Ray Scattering Experiment & Plum-Pudding Model

My teacher said, "Rutherford thought that all the Alpha particles would directly go through the gold foil without any collision if the plum pudding model was right. Because, as said in plum ...
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1answer
65 views

Schrodinger's Equation and Wave Function

So I understand that there exists the shrodinger's equation, which on solving,gives the wave function of an electron. The wave function as I understand, gives all possible information about an ...
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1answer
87 views

Is this bond Ionic or Covalent, and why? AlBr [closed]

We know a compound could form between NaCl because they are +1 and -1 ions which make them both into a complete valence set. Could a compound form between Al and Br, for example, and what type of bond ...
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35 views

Does the electron in a neutral hydrogen atom ever exist in the p, d or f sublevels?

I learned that the electron in a neutral hydrogen atom can be excited to higher levels. But there are different sublevels in the levels. For example s, p, d and f. Does the electron only jump from s ...
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Why do electrons jump back after absorbing energy and moving to a higher energy level?

Electrons in a shell absorb energy and move to higher energy levels, but they release their energy and jump back to the shell they originally were in. Why do they jump back? Why can they not keep ...
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118 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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What does orbital mean, exactly? [duplicate]

My teacher told me that orbital is the probability distribution data of the electron around nucleus which is amplitude data in a way. An example of how my teacher actually told what it means involves ...
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1answer
68 views

Why is the atomic mass unit less than the mass of both a neutron and a proton? [duplicate]

The atomic mass unit is $1.6605 \times 10^{-27}$ kg. This is less than the mean of the masses of 6 protons and 6 neutrons. How do we account for the lower mass ? My understanding is that some of the ...
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3answers
347 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 ...
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How is this possible in mole concept? [closed]

L = $6.022*10^{23}$ If I have one atom of oxygen , it has exactly L value. Now 2 atoms of a oxygen have 2L value.(Note that I mean 2O and not $O_2$here) Well , if we take a molecule made up of 2atoms ...
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1answer
81 views

What does Pauli’s exclusion principle mean in atomic or fundamental way? [closed]

It means is that no electron can have same n , l and $m_l$ but can have two different spin quantum number. I want to know why is this rule valid?Means there must be some other things happening also ...
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152 views

Is this diagram correct for difference between 2N and N2

There is 1 $\ce{N2}$ molecule formed with 2 atoms of nitrogen. 2N is 2 separate nitrogen atoms which have not formed any bond.Reasons could be that they didn’t get enough energy to form bond so they ...
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1answer
71 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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Why hydrogen gas tube produce hydrogen atomic spectrum

To measure the atomic hydrogen spectrum people often uses hydrogen gas tubes as light source. Since the gas in the tube is the molecule $H_2$ , why we obtain the spectrum of atomic hydrogen? My guess ...
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1answer
65 views

Why does matter have spaces between them? [closed]

If you mix sugar Crystal in a glass of water and mix it well, the level of water will not rise.The reason they say is that matter have spaces between them.If matter have spaces between them , How ...
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69 views

“Isotopes” in a molecule?

I just learned that atoms of the same element can have different mass because of they are isotopes. If there are two isotopes in which each reacts to form the same thing. Would the mass differ in each ...
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Hydrogen and Hydrogen ion

Is it correct that a hydrogen atom only has 1 electron and 1 proton since the atomic mass is 1? Also, is the hydrogen ion composed of a single proton and no electrons? In an ionization process we know ...
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Reason for needing multiple radii for the same atom [duplicate]

Why do we need different types of atomic radii? Why can't there be just one radii for an atom?
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109 views

In metallic bonding, what causes a metal to lose its outer electrons and become an ion? [duplicate]

In metallic bonding, what causes a metal to lose its outer electrons and become an ion? I am trying to understand metallic bonding, atoms and ions.
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54 views

Why does covalent bonding not break down if observer effect can be applied to atomic electrons? [closed]

The observer effect in quantum mechanics states that when unobserved, quantum particles such as electrons can simultaneously occupy two different states. In an atom of any element, where there are ...
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325 views

Does the 4s orbital really have a higher energy level compared to 3d? [duplicate]

For writing the electronic configuration of the $\ce{Fe^2+}$ ion, you need to remove two electrons (as it is an ion) which are from the highest energy level. Apparently, this would be $\mathrm{4s}$ ...
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1answer
43 views

Could observer effect cause electrons in one orbital to be found in another?

The observer effect states [1] that when unobserved, absolutely small particles like electrons can simultaneously be in two different states at the same time. If we look at an atom of any element, ...
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171 views

Rules to follow while writing a chemical formula for polyatomic ions

In Science, textbook for class IX, chapter $3$ [1,p.38], it states: The rules that you have to follow while writing a chemical formula are as follows: in compounds formed with polyatomic ions, the ...
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Illustrating moles with sand grains, Are there more moles of SiO2 in a grain than moles of sand on the earth

I have been trying to understand the scale of atoms, thinking about sand grains as an example. With approximately $7.5\times10^{18}$ grains of sand on the earth that is $1.25\times10^{-5}$ moles of ...
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1answer
485 views

How did Mendeleev know elements from compounds or mixtures?

I read that Mendeleev initially thought didymium was an element, but it was actually a mixture. How did he know the rest of the chemicals in the periodic table were elements and not compounds, ...
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Confusion with definitions of mass [duplicate]

What is the difference between: atomic mass relative atomic weight relative isotopic weight standard atomic weight atomic weight relative atomic mass I am told by Wikipedia that: relative atomic ...
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422 views

What is the dimension of Avogadro's constant?

What is the dimension of Avogadro's constant ($N_\mathrm{A}$). On Wikipedia it says it is dimensionless, but in Nigel Wheatley's article (pdf) On the dimensionality of the Avogadro constant and the ...
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1answer
114 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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1answer
201 views

What were the expectations of Rutherford's gold foil experiment? [closed]

At the time when Rutherford's gold foil experiment was performed, Thomson's plum pudding model was believed to be true (at least by Rutherford himself and his students). With this model in mind ...
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1answer
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How do orbitals overlap in difluorosilane? [closed]

In $\ce{SiH2F2}$ four orbitals of silicon $(\mathrm{3s},$ $\mathrm{3p}_x,$ $\mathrm{3p}_y,$ $\mathrm{3p}_z)$ overlap with two hydrogen $(\mathrm{1s})$ and two fluorine $(\mathrm{2p}).$ I want to know ...
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207 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
694 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
579 views

Trend in atomic volume across a period [closed]

"Atomic volume decreases along a period, reaches a minimum at the middle, and then increases for the rest of the period" Why does the atomic volume, along a period, initially decrease, ...
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Why doesn't core charge increase down a group? [closed]

Atomic radius increases down a group because the electrons feel a lesser attraction to the positive nucleus (due to shielding from inner shells). Why then, doesn't core charge decrease seeing as core ...
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50 views

Atoms and their vibration [closed]

We all know that the atoms in any solid matter vibrate about their mean position but why do they do so?? What will happen if they stop vibrating??
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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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483 views

Ground state term symbol for Cerium (Ce)

I need to calculate the term symbol of the ground state configuration of Cerium. The electron configuration is: $[Xe] 4f^1 5d^1 6s^2$ Since the d and f electrons are in different subshelles, they are ...
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1answer
67 views

Why is the amu of chlorine-35 less than 35? [duplicate]

My book says that a proton weighs 1.0073u, a neutron weighs 1.0087u, and an electron weighs 0.00055u. Now, why is the mass of chlorine-35 equal to 34.969? Are there not 17 protons, 18 neutrons, and ...
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The meaning of magnetic quantum numbers' values

The $\mathrm{m_l}$ values in quantum mechanics, $1, 0, -1$ for p orbitals for example, do they refer to specific orbitals? Like, does $\mathrm{m_l} = 1$ refer specifically to $\mathrm{p_x, m_l} = 0$ ...
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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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What is the general or ideal equation for the radial wave function?

I came across this question on the internet: What is the value of $(n + l + r)$ in a given wave function, where $n =$ principle quantum number and $l =$ azimuthal quantum number and $r =$ total ...
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265 views

Why we need the average atomic mass? [closed]

I know , Average Atomic Mass of an element is - the sum of the Masses of its isotopes,each multiplied by its Relative Abundance percentage (in decimal notation). But what confusing me is, what is ...
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What is the empirical formula of a compound where the mass ratio of sulphur and oxygen is 2:3?

This is how I tried to solve it: $$\frac{2}{3} = \frac{0.67}{1}$$ $$\frac{32.06}{16} = \frac{2.00}{1}$$ $$\frac{0.66}{2.00} = \frac{0.33}{1}$$ I assumed by the result that if for every $\pu{1g}$ ...
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395 views

Why are moles of compounds have only 6.022x10 23 atoms? [closed]

I am a bit stuck on a basic chemistry concept. I understand that the Avogadro number indicates the number of chemical entities it has (ion, molecule or atom) What I don't understand is that when you ...

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