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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 do I tell what the chemical composition of a rock is? [closed]

I love to look at rocks, they are so fascinating, but I always find myself wondering how many of each kind of atom are in this particular rock, or how many atoms in total. The only thing I can tell is ...
Boo Lightning's user avatar
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88 views

Why isn't the slope in atomic number vs calculated atomic radius graph same for different block elements?

This is a graph of atomic number vs calculated atomic radius for different block elements: Two questions: Why isn't the slope line same? why does the transition metals slope taper off to zero, ...
Coo's user avatar
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Perforated Cathode in Anode Ray Experiment

While studying about the anode ray experiment (E. Goldstein), I had a doubt pop up in my head. In the experiment, a perforated cathode has been used. What is the exact reason behind that? Upon ...
entropy's user avatar
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2 answers
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What does "predicted" mean in an electronic configuration?

I've noticed the term "(predicted)" appearing at the end of electron configurations for heavier elements. Could you explain what it signifies and the reason behind it? I haven't been able to ...
uggupuggu's user avatar
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3 votes
2 answers
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Why aren't there different peaks for different IE in PhotoElectron Spectroscopy (PES)?

The way I understand PES is that you shine a light on a bunch of atoms and measure the kinetic energy of photons to determine ionisation energies (or energies of electrons... is that different?). I ...
Maddy's user avatar
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Why is the concept of penetration power only applied to Be and B, and not to Be and C, N, O, F?

In my book, it is stated that the ionization energy of Be is greater than that of B because the electron removed in Be is in the 2s orbital, while the electron removed in B is in the 2p orbital. This ...
Peter swift's user avatar
3 votes
3 answers
116 views

Challenging Orbital Restrictions

According to the n-l-1 formula for nodal count, wouldn't 1p, 1d, and 1f orbitals be possible since l (angular momentum quantum number) can be 1, 2, and 3 respectively for a principal quantum number (n)...
White knight's user avatar
4 votes
1 answer
139 views

How did early chemists work out the number of protons in the nucleus?

I was reading about the history of the periodic table and the description of an element’s atomic number as its proton number. I couldn’t find the source again but it was stated that they figured out ...
powerful_bob's user avatar
-2 votes
1 answer
55 views

Stability of atoms with 4 valence electrons [closed]

How do atoms with 4 valence electrons stabilize? Do they gain or lose 4 electrons? This might be a bit of a stupid question, but I'm not sure and I can't find anything online.
riesen mihar's user avatar
1 vote
1 answer
158 views

Wave function in Schrodinger's model

I am trying to wrap my head around the Schrodinger's quantum mechanical model of an atom. According to the NCERT$^1$, the Schrodinger's equation is given by: $$\hat{H}\Psi=E\Psi$$ where $\hat{H}$ is ...
Harikrishnan M's user avatar
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On the relativistic contraction of orbitals

In Platinum $\text{Pt}$, why do $\text{s}$ and $\text{p}$ orbitals contract when electrons start travelling at relativistic speeds $|v|\sim c$, while $\text{d}$ orbital expands? The way I reasoned ...
Kutasov's user avatar
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1 answer
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What is the cause of different metal densities? [duplicate]

What causes differing density? Is one metal more dense than another because the atoms are larger (more mass per atom), or because the atoms are closer together? Or both? Example: Aluminum Density: ...
D.W.'s user avatar
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1 vote
1 answer
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Does ionisation change the physical/chemical properties of an atom?

From what I have learned, the number of electrons on the outermost shell (called the valence electrons), determines the chemical properties of an atom, this is why elements in the same group have ...
user144179's user avatar
2 votes
0 answers
93 views

Law of multiple proportion fitting in the notion of an atom

I have been reading about atoms. Currently, I am referring to the book "Atom : Journey across the subatomic cosmos" by Issac Asmov. I believed that if we start dividing something so we can ...
Shekhar Dangi's user avatar
2 votes
0 answers
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how can I tell compton versus coherent scatter apart?

I am trying to get a better understanding of compton and coherent scatting, along with all the other interactions. It has seemed like a lot to memorize and I am trying to find ways to more easily ...
Maddy's user avatar
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1 answer
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Mg2+ ion formation [duplicate]

Why does Mg not form a Mg+1 ion, even though its second ionization energy is much higher than the first ionization energy? (I know that an ion should resemble the noble gas closest to the element from ...
Saar Segen's user avatar
-1 votes
1 answer
76 views

What are the building blocks of matter? [closed]

Question 1: If atoms are made up of fundamental particles, then why we say that atoms are the building blocks of matter? Atom, the basic building block of all matter. (1) Atoms are the basic units ...
Altair25's user avatar
1 vote
1 answer
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How was it known certain materials were elemental (Hydrogen 1766, Phosphorous 1669, ...) before Dalton showed that matter was made of atoms in 1803?

Dalton showed in 1803 that matter was made of atoms rather than continuously distributed. But phosphorous, hydrogen, and other elements were identified before this discovery. How could they have known ...
imrobert's user avatar
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-4 votes
2 answers
143 views

How does the same electron orbit both atoms in covalent bond? [closed]

During elementary school chemistry, when they teach about the covalent bond, they say that both atoms need the electron but they can't lose or gain them so they share it. And for instance they show us ...
Yug Ahuja's user avatar
-1 votes
3 answers
211 views

What are the differences between an alpha-particle and a helium 2+ ion?

What are the differences between the alpha particle and helium 2+ ion? Or are they the same? Do differences arise because of the process by which they are formed?
John Mathew's user avatar
2 votes
1 answer
239 views

Measurement of the number of electrons, protons and neutrons inside an atom

How do we measure the number of protons, electrons, and neutrons inside an atom? What experiments can be conducted to determine, for example, that an iron atom contains 26 protons?
doca's user avatar
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1 vote
3 answers
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Comparing Succesive Ionisation Energies

I am trying to understand successive ionisation energies. In particular, an explanation for why the second ionisation energy is greater than the first ionisation energy. I'm looking for a clear and ...
Charles Dickens's user avatar
7 votes
1 answer
126 views

Confusion about the number of microstates for orbitals

I am very confused about the microstates for a specific orbital. Let's suppose I have an electronic configuration $$ \ce{[\dots] 2p^5} $$ Considering the symmetry of the orbitals and the "...
Kubrik's user avatar
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-4 votes
2 answers
105 views

Mechanism of S2Cl2 and NaHSO3 [closed]

I learned that NaHSO3 reacts with S2Cl2 to give Na2S4O6 as product. After looking up the structure of Na2S4O6, it confuses me that four sulfur atoms connect together. I couldn't figure out the exact ...
Shira's user avatar
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-4 votes
1 answer
229 views

why chemical bond between Na and Cl happens [closed]

We know that if Cl and Na get too close, they produce ionic bonding. Cl has 17 proton and 17 electrons and is considered stable. Na has 11 protons and 11 electrons and is considered stable. I ...
Chemistry's user avatar
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-1 votes
1 answer
62 views

when would copper material have free electrons [closed]

If you imagine a wire of copper(note that I am not talking about electricity at all). Just only a wire of copper or copper metal or whatever full of copper atoms. We know that each copper atom has 1 ...
Chemistry's user avatar
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-4 votes
1 answer
71 views

what happens to electron after beta minus decay [closed]

In the beta minus decay, electron is emitted from the nucleus. It depends on the previous nuclei(that was before beta decay) how much energy emitted electron will have. After this event, Internal ...
Giorgi Lagidze's user avatar
-4 votes
1 answer
71 views

Energy levels for H atom [closed]

Problem Statement: The number of orbitals (for H-atom) which have greater energy than $3p_y$ orbitals: $3s, 3p_z,3d_{z^{2}},3d_{x^{2}-y^{2}},2p_y, 4d_{z^2}, 4p_{y}$ The solution says that energies ...
PurposeHonest's user avatar
-5 votes
1 answer
59 views

Are elements made out of many atoms? [closed]

So im reading a chemistry book right now, and always thought an element is made out of ONE atom, with special properties that make it this element. Amount of Protons, neutrons and electrons. But this ...
Sosse's user avatar
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1 vote
2 answers
667 views

Does effective nuclear charge decrease down the group?

I've read that the effective nuclear charge increases down the group. This seems incorrect. As we go down the group the number of protons increases and the shielding constant also increases. We can ...
James Chadwick's user avatar
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0 answers
65 views

Can someone elaborate what it means when its said that electron shells do not exist in multi electron systems?

I'm an undergraduate student in chemistry. I'm trying to grapple with all the new stuff we're learning and making sense of it. Now I want to know if electron shells really "exist" in multi ...
Stu's user avatar
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-3 votes
2 answers
135 views

Why does atomic radius decrease across periods? [closed]

My textbook says that this happens because the number of protons, and thus the total positive charge, increases - a greater attractive force acts on each electron. The book says that this is despite ...
Sak's user avatar
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-3 votes
1 answer
197 views

Have we ever managed to "add" a proton to a nucleus? [closed]

Have chemists or physicists ever managed to "add" a proton to an atom in order to create a new element? For instance, a hydrogen atom has one proton; has anyone managed to give a proton to a ...
Mailbox's user avatar
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0 answers
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The first electron affinity of an atom

I've read that the first electron affinity is always negative, meaning that energy is always released upon the addition of this first electron. However, I don't think this will apply to noble gases. ...
Quin Gardiner Bax's user avatar
0 votes
1 answer
44 views

Masses of atoms and molecules [duplicate]

This is my understanding so far: Average atomic mass is the mass of an element considering isotopes and is measured in atomic mass units. However relative atomic mass is the average mass of an atom ( ...
Quin Gardiner Bax's user avatar
0 votes
1 answer
357 views

If the effective nuclear charge of Beryllium(Be) is less than Sodium's(Na), how is the ionization energy of Be higher than Na?

According to Slater's rules the effective nuclear charge of Beryllium and Sodium is 1.95 and 2.20 respectively. That means that the outermost electron of Na feels a stronger attraction from the ...
CaptainAmerica Whyso's user avatar
3 votes
1 answer
876 views

How many carbon, hydrogen, oxygen, nitrogen, and phosphorus atoms are there in the observable universe?

If I could somehow reliably count all the carbon, nitrogen, hydrogen, oxygen, and phosphorus atoms in the observable universe, what number would I come up with?
moonman239's user avatar
2 votes
0 answers
38 views

Is determination of nuclidic mass by nuclear reaction currently state of the art for any nuclides?

In Section 4.9 of Linus Pauling's General Chemistry Book (Dover 1988 edition, a copy of the WH Freeman and Company 1970 edition) he describes the principle behind the determination of nuclidic mass by ...
Buck Thorn's user avatar
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-2 votes
1 answer
74 views

If you give an electron in a subshell more energy, does it simply "jump" to the next energy level?

Suppose you have an electron in the $\ce{2s}$ subshell of an atom. If energy is given to it, does it simply jump to the next energy level (into the $\ce{3s}$ subshell), or does it move into $\ce{2p}$?
Shane's user avatar
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-3 votes
1 answer
103 views

Can it be said that an electron transfer between two neutral atoms comes from the neutral atomic electric field? [closed]

Let us consider the example of Na and Cl. Both atoms are called "neutral" simply because they have the same total number of protons as electrons, yet they have a very weak electric field ...
iwab's user avatar
  • 359
-4 votes
2 answers
152 views

Relative atomic mass calculation [closed]

In my textbook it states that relative atomic mass of an element Y is equal to the average mass off one atom of element Y multiplied by 12 divided by the mass of one atom of carbon 12. What is the ...
Jeremy Clarkson's user avatar
-1 votes
3 answers
895 views

How are the number of neutrons changed in an atom? [closed]

I'm studying isotopes in high school and I don't understand how it works. From my understanding, when neutrons are added or removed, an isotope is created. To calculate the number of neutrons, the ...
user128108's user avatar
9 votes
1 answer
715 views

Why does the same electron transition release photons of different frequencies for some elements?

Question: For elements in the same period with different numbers of valance electrons, why does the same electron transition release photons of different frequencies? Example: For valance electrons ...
Bryan351018's user avatar
-2 votes
1 answer
122 views

How can Planck’s equation and the wave equation simultaneously coexist with contradicting each other? [closed]

The equations: E=hf (Planck’s equation, where E is the energy, h is the Planck’s constant and f is the frequency) and V=fλ (where v is the speed (in a vacuum), f is frequency and λ is the wavelength) ...
Kirandk's user avatar
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2 votes
1 answer
205 views

Why are ions in a mass spectrometer accelerated through electric plates? [closed]

I was reading an article on the AP Chemistry course in Khan Academy about mass spectrometry, which had this: ... ions are then accelerated through electric plates and subsequently deflected by a ...
archthegreat's user avatar
-2 votes
2 answers
3k views

Can an element be a single atom or a molecule made up of atoms of the same element?

Some online websites and some books as well suggest that elements are either atoms (e.g. Ne) or molecules (e.g. $\ce{H2}$, $\ce{O2}$). Original source: Tro, Chemistry: A Molecular Approach (2008) ...
Level1's user avatar
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-5 votes
1 answer
72 views

What is the energy difference between inner subshells?

For exemple, in silver the energy difference between the 4d 5s subshells is ≈ 4 eV (in the ultraviolet region, that's why it has no color, etc.), but what is the energy difference between some of its ...
Walter Grosse's user avatar
-5 votes
1 answer
61 views

How do I calculate q/m? [closed]

My chemistry book (Mortimer in German) has the following question: Calculate the value q/m for the following Ions: ("mit Masse" meaning "with mass") How do I calculate q/m? Thanks ...
Clemens's user avatar
6 votes
1 answer
241 views

where could I find the standard atomic orbital energy of all elements?

I am trying to find the standard atomic orbital energy of all elements. Here is the data I found in some old books: I am looking for some more modernized data, I tried to look for the data in the CRC ...
Jack's user avatar
  • 73
-3 votes
1 answer
476 views

What does it mean when we say an atom has infinite energy levels/shells? [closed]

My chemistry teacher told that an atom has infinite energy shells according to Bohr model , where electron reside according to its angular momentum and energy. But in lower classes/ grades I have ...
Shinchan Nohara's user avatar

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