Smallest particle still characterizing a chemical element. It consists of a nucleus of a positive charge, carrying almost all its mass and electrons determining its size. This tag should be applied to questions that specifically concern these particles and their properties.

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Doubt about Rutherford's experiment

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
34 views

Spin of electrons about it's own axis, release of energy & COLLAPSE of atom?

An electron spins about it's own axis. So it has rotational accln. Thus, according to Maxwell's Electromagnetic Theory , Rotational Kinetic energy must be released. Thus, at some pt. of time , ...
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2answers
63 views

What is the reason why protons and electrons do not collide?

can someone give me an intuitive picture of why electrons don't collide with protons? I know that electrons move in a sort of cloud, which is our 'orbital', and that they mainly behave like ...
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0answers
32 views

Why are Alkali Metal Ions Soluble?

I think the question needs no elaboration. Why are salts containing Group 1A cations extremely soluble in water? I speculate that the reason involves the low charge density of those ions in a given ...
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0answers
22 views

Size of Germanium compared to Silicon

Gallium has a smaller atomic radius than Aluminum because of the poor shielding effect in Gallium due to the presence of 3d orbital. However why does this not happen with Germanium and Silicon, ...
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0answers
23 views

Extra-stability of half & fully-filled orbitals + release of exchange energy [closed]

I read that half-filled or fully-filled orbitals are extra-stable bcz exchange energy,due to symmetry of spin, is released . Thus, due to such release of energy of the system, shouldn't the atom ...
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0answers
22 views

table of expanded electronic structures of atoms

Where can I find the table containing expanded electronic configurations for atoms in periodic table, showing how outer electrons are distributed between different atomic orbitals? Well, i need just ...
0
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1answer
18 views

What is generally meant by distinct line spectrum?

In a single hydrogen atom the electron is excited to 6th orbit. The book says maximum 5 distinct spectral lines are possible when the electron comes to the ground state. Looks like they have only ...
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1answer
39 views

Why most of the atoms with fully filled outer orbits are gaseous?

Most of the elements with fully filled outer orbits are gaseous in nature (He, Ne, Ar, Kr, Xe, Rn) with exception of Uuo (as per Wikipedia its solid). Why these fully filled outer orbit elements are ...
0
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1answer
41 views

A problem on rate of diffusion

At a particular temperature and pressure it takes just 8.256 minutes for a 4.893 liter sample of Neon (Ne) to diffuse through a porous membrane. How long will iodine diffuse in similar conditions? ...
2
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0answers
63 views

Is a substance's band gap related to it's flame test colour?

This is really not my field at all, but I am intruiged by the cause of different metals emitting different wavelengths of light. To my knowledge, the more energy needed to "excite" an electron, the ...
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0answers
30 views

Difference in properties between a substitutional and an interstitial alloy?

What I know is, that in a substitutional alloy, the atoms of the solute metal take positions normally occupied by the solvent metal atoms, as they are more or less the same size. In an interstitial ...
6
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2answers
260 views

The effects of adding neutrons to an atom

So neutrons are neutral in terms of charge, and adding neutrons to an atom affects its atomic mass. But when neutrons are added to the nucleus, the nuclear radius would be affected. Couldn't that ...
0
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1answer
74 views

What are the height and width of the large and small nodes of the sp3 hybridized orbitals of carbon and silicon?

I will make an effort to interpret answers based on wave functions, but I am a senior pursuing a bachelor's degree in Biology, so I don't have the background in quantum physics for a purely ...
1
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1answer
34 views

Find the amount of atoms for a given mass

The atomic mass of two elements A and B is 40 and 80 respectively. If x g of A contains y atoms, how many atoms are present in 2x g of B? I have tried to solve by assuming that x g of A has y atoms ...
0
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1answer
41 views

Numerical value of mole

Why is the numerical value of a mole of atoms equal to the atomic weight? For example, hydrogen has an atomic weight of 1.008, so 1 mole of hydrogen atoms has a molar mass of 1.008 g/mol. Why?
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2answers
712 views

Can we recycle garbage with the principles of mass spectrometry?

'Mass Spectrometry (MS) is an analytical technique that sorts ions based on their mass (or "weight"). Mass spectrometry is used for many chemical analyses, ranging from the analysis of a complex ...
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2answers
94 views

Is nucleus at the centre of the atom? If so why?

In postulates of Bohr's model of the atom, it is said that the nucleus is at the centre of the atom. In Rutherford’s α scattering experiment he said that out of 20,000 alpha particles only 1 ...
0
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1answer
63 views

How can I search molecules by constituent atoms

Given a set of atoms, I would like to find (some / the most common) molecules that include only (some/all) atoms of the set. Is there any online search engine that can do this? E.g. Atoms={C,H} ...
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1answer
74 views

How to calculate Madelung's constant for NaCl?

Madelung's constant for $\ce{NaCl}$ is $1.748$. What I tried to so is sum up all the individual interactions into $1$ component where the $X$s are the nucleus and the electron if it was a $2$ atom ...
0
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0answers
68 views

Why does the electronic distribution of Calcium is 2,8,8,2 when 3rd shell(M shell) can hold 18 electrons?

I know by the formula 2n^2, the total no. of electrons in K, L, M, N shells are 2, 8, 18, 32 respectively. But here electronic configuration of Calcium is not correct if we go solely by this formula. ...
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1answer
33 views

Alternative to a proton [closed]

I know I might sound terribly stupid but the idea just hit me. We define elements on the periodic table as "lumps" of matter with specific amount of specific particles (electrons neutrons and protons) ...
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0answers
45 views

Anomalous Electronic Configuration of Thorium

The electronic configuration of thorium ($Z=90$) is $5\mathrm f^0 6\mathrm d^2 7\mathrm s^2$. But, according to the aufbau principle, the electrons should first enter the $\mathrm f$ subshell and not ...
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0answers
20 views

How do I calculate the valence(y) of an element, knowing it's valence electrons [duplicate]

How do I calculate the valence(y) of an transition metal or just any element in the periodic table? I know it has something to do with valence electrons(The electrons in the outer most shell, right?), ...
0
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1answer
45 views

How to find electronic configuration of an atom? [closed]

I would like to know how to find the electronic configuration of an atom such as Potassium without using the 1s2, 2s2, 2p6 ... method to explain as I don't get it at all. Try to orientate the answer ...
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1answer
32 views

Why does ionization increase from Li to Be? [duplicate]

If ionization energy decreases from $\ce{N}$ to $\ce{O}$ due to the pairing of electrons (causing electric repulsion and greater potential energy) in the $\mathrm{2p}$ orbital in the $\ce{O}$ atom, ...
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0answers
49 views

Use of statistics in this field

I am currently pursuing a statistics course and I an interested in knowing how can statistics help this field in future. (I am interested because I love chemistry very much) Specifically, are there ...
0
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1answer
116 views

Which statement is correct about electron orbitals and energy levels?

Which statement is correct about electron orbitals and energy levels? A. Yttrium, $\ce{Y}$ ($Z = 39$) is the first element in the periodic table with an electron in a f sub-level. B. The ...
2
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1answer
54 views

What is the significance of Law of Multiple Proportions?

I cannot understand how the Law of Multiple Proportions is significant, or how does it further improve over Law of Conservation of Mass or Law of Definite Proportions. From Wikipedia: If two ...
0
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1answer
74 views

Ionization energy comparison between K+ and Cl-

So I have encountered a question which looks very suspicious to me. If you have $\ce{Cl-}$ and $\ce{K+}$, Can you say that $\ce{K+}$ has more ionization energy than $\ce{Cl-}$? We know for a fact ...
3
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1answer
113 views

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 ...
5
votes
1answer
305 views

Is NaCl crystal always going to have even number of atoms?

I just read: In $\ce{NaCl}$, atoms don't aggregate so as to form discrete molecules but they are held together in a network structure. The ratio of the $\ce{Na}$ to $\ce{Cl}$ atoms in a sodium ...
8
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1answer
281 views

Existence of orbitals

Do orbitals exist even when they are not occupied? For example: $\ce{Cr^{+3}}$ has the configuration $\ce{[Ar]}\mathrm{3d^3}$ with the other two $\mathrm{3d}$ orbitals empty. We know the other two ...
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2answers
2k views

Is iron the most stable element in the periodic table?

According to the binding energy per nucleon vs mass number graph, it is observed that iron-56 has the maximum value of binding energy per nucleon (8.75 MeV).It means that Iron-56 is the most ...
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1answer
78 views

Can we add an electron to an atom?

Say that we have an atom which is inert, or stable. How would one go about adding one electron. Is it possible?
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1answer
248 views

If the reactivity of group 1 elements increases down the group, why is this not the case for halogens?

I was wondering, as you go down a group, the atoms get bigger... This means that the electrons in the outer shell are further away from the nucleus, and so the attraction decreases and it is easier ...
5
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1answer
94 views

What is the electron configuration for Uuo with a charge of 2-?

I was writing a cool program that determines the electron configuration of elements for me, and I wondered what would happen if you went over 118 — the "limit" of my program. So, what is the ...
3
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1answer
3k views

How many valence electrons does an atom of Cu have? [duplicate]

$\ce{Cu}$ electron configuration: $\mathrm{4s^1 3d^{10}}$. Ok so the answer is $11$, shouldn't it be $1$ since the $\mathrm{d}$ shell is already filled up?
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1answer
76 views

How is Molecular mass is the molecular weight? [closed]

Wikipedia says molecular weight is the mass!! I can't get it the weight is the mass times 10 so we cannot neglect that, because 10 amu is not equal to 1 amu
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2answers
57 views

Is water a heterogeneous molecule? [closed]

My question is based upon the statement found here: an element may be homogeneous on a larger scale, compared to being heterogeneous on a smaller scale. This is known as an effective medium ...
12
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2answers
891 views

Protons and the Heisenberg principle

The Heisenberg uncertainty principle implies that it is not possible to calculate the position and velocity of a body at the same time accurately. Electrons follow this principle since their orbitals ...
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1answer
75 views

Can anyone give me detailed logical solution to my questions? [closed]

What is 1 amu? From where it is derived? Why it is compared with carbon-12? Why it was once compared with hydrogen-1? and now its not? Can anyone please explain me logically? And what would have ...
0
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0answers
20 views

How octet configuration of atoms make them stable? [duplicate]

How the octet configuration of atoms making the atoms stable? How it helps them?
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0answers
77 views

Why are the d-orbitals so named?

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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0answers
65 views

Mass number, (relative) atomic mass, average mass

What is the difference between mass number, atomic mass and average atomic mass? I know the mass number is the amount of protons + the amount of neutrons. The average mass is the weighed average of ...
0
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1answer
118 views
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1answer
211 views

Why is there no neutron in protium?

My chemistry teacher told me once that every atom should have at least as many neutrons as protons, to keep the electrons from crashing into the nucleus. Protium, however, does not have any neutrons ...
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1answer
195 views

How many atoms of helium are in the chamber?

A $22.7 \,\mathrm{L}$ helium-filled chamber at $298\,\mathrm{K}$ has a tiny hole of area $1.63 \times 10^{-5}\,\mathrm{mm^2}$ punched in it through which is leaking helium at a rate of $2.25 \times ...
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1answer
29 views

Do you refer to a bonded atom as an “ion”?

Take H2O, would you call the H a hydrogen ion? Or just a hydrogen atom?
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1answer
524 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 ...