A basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons.

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What defines an element's taste?

A useful post by @Martin indicated that probably the naming of Sweetwater town is because of the sweet tasting lead compounds in it's water. Then my question arose. I know that the taste of any ...
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1answer
24 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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42 views

Why is Graphene So Strong?

There has been a lot of news about Graphene since its discovery in 2004. And as we are all told it is a revolutionary material which is very strong, conductive and transparent. But what is it about ...
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59 views

Which sample contains the greatest number of atoms?

Which has the greatest number of atoms from the following samples, given 1 gram of each: 1) sodium phosphate ($\ce{Na3PO4}$) (MM : 163.94) 2) sodium phosphide ($\ce{Na3P}$) (MM:99.94) 3) potassium ...
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75 views

Does radioactivity affect chemical reactions

Do compounds of radioactive elements show a bit different behaviour, and what happens when the radioactive part of the given compound decays, e.g, Radium Chloride, what happens to it when radium ...
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1answer
13 views

Does STED microscopy allow us to see reactions happening on a substrate

This years nobel prize for chemistry went to nanoscopy using STED as a control mechanism. I have seen the atoms/molecules of a lattice vibrating as shown by Stefan W Hell in a presentation at some ...
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1answer
726 views

If radium has such a long half-life, how can radon possibly be a threat to us?

If the probability is so low that a radium atom will decay into radon at any given time (the half-life is over 1600 years), then there will be a low amount of radon produced, granted it will be ...
4
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1answer
52 views

Why is water transparent?

Some substances like Copper Sulfate for example have vivid colors. But why is water transparent? Does it not emit any visual light from the electromagnetic spectrum?
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1answer
12 views

definition of relative atomic mass

I found out there are 2 definitions of relative atomic mass. First definition is Ar is the mass of 1 atom of an element relative to 1/12 the mass of carbon-12 atom. It can be found in any chemistry ...
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37 views

Which group does germanium belong to?

$\mathrm{Z= 32}$ $\mathrm{1s^2\ 2s^2p^6\ 3s^2p^6d^{10}\ 4s^2p^2}$ According to me it belongs the $\mathrm{IV\ B}$ group since it has the $\mathrm{d}$ completed, but it belongs to $\mathrm{IV\ A}$. ...
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2answers
28 views

How can we confirm the number of protons in an atom?

The periodic table tells us that there are 6 protons in a carbon atom. Is there a way to verify this first-hand? Or are we just expected to believe it unquestioned?
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1answer
38 views

How to interpret a luminescence intensity vs wavelength graph?

Luminescence is defined as the amount of light emitted by a atom. But what confounds me of this graph is the fact that all the peaks are of the same height. In addition, there are no peaks in ...
3
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56 views

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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1answer
35 views

Why is Electrostatic Potential Energy positive when the charges are like?

We know that in an atom charge of an electron at infinity is zero. As it approaches the nucleus it become more and more negatively charged. We also know that E.P.E is positive when charges are like ...
6
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1answer
122 views

How does the radial distribution function of Vanadium differ from that of Calcium and how does this affect the ionic electron configurations?

When Vanadium is ionised it loses the 4s electron first, meaning that it's 3+ ion has a different electron configuration to Calcium despite it being isoelectronic. Can it be explained in terms of ...
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0answers
23 views

Using knowledge of radial distribution functions, how is it possible to explain the different electron configurations of V3+ and Calcium [duplicate]

I recognize that the 3d orbital decreases in energy to lower than the 4s once it becomes occupied (even if I don't completely understand why?!). However, how is the difference in electron ...
3
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1answer
82 views

Why are all the orbitals that have the same principal number in Hydrogen degenerate?

In hydrogen, all orbitals with the same principal quantum number 'n' (1,2,3...) are degenerate, regardless of the orbital angular momentum quantum number'l' (0,1...n-1 or s,p,d..). However, in atoms ...
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53 views

Doubt on Photoelectric effect

In the experiment to conduct photoelectric effect a clean metal was irradiated by monochromatic light of proper frequency, electrons are emitted. Why was monochromatic light used in the experiment? ...
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1answer
33 views

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

Today, I studied Slater's rules for calculating the effective nuclear charge. But, 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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1answer
631 views

What holds atoms together?

1.I know atoms are held together by Ionic and Covalent bonds and i understand the ionically bonded atoms are held together by electrostatic forces. What about covalent bonds? 2.How are molecules of ...
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1answer
45 views

What is the structure of the Nucleus? [closed]

The structure of an atom is well known to me as something like this: But what is the accurate structure of the Nucleus ? What is the arrangement of the Protons and the Neutrons or any of the other ...
5
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2answers
142 views

Conversion of one atom to another to get the element of the latter atom in abundance

One child who is in 9th standard has claimed to have find a solution to all practical physical problems. On asking for details, he said that all periodic elements has common components, i.e. ...
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1answer
37 views

Can the electron configuration of Te be written that way?

Normally, the electron configuration of Te is known as: $$\begin{aligned} {[Kr]} 5s^2 \ce{4d^10} 5p^4 \end{aligned}$$ Then, one day I was asked in a exam if this can be written also as: ...
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1answer
324 views

An atom of silicon in its ground state has how many electrons with quantum number l = 1?

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 l ...
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Why do atoms “want” to have a full outer shell?

Okay, so I know that this is about filling the orbitals of the atom, and I understand that. What I don't understand is why? For example, an Oxygen atom has 8 protons and 8 electrons spinning around ...
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134 views

Converting from Grams to Molecules

I was doing some problems from the textbook on converting between units using dimensional analysis and I came across this problem. A vat of Hydrogen Peroxide ($\ce{H2O2}$) contains 455 grams of ...
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1answer
74 views

Which atoms in a given amino acid are able to form hydrogen bonds with water?

Can anyone help me with this question I have tried everything. I know hydrogen bonding is with F,O, or N but every time I select those is says it's wrong. Any help is appreciated
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Why there are different elements in nature? [closed]

Why there are different elements in nature with different chemical properties while all atoms are made from three subatomic particles? Are these different elements have been created accidentally, or ...
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3answers
944 views

Is a single atom stable?

It is well known that single atom of oxygen is not stable, and it forms $\ce{O2}$ molecule. But elements like carbon form a network of repeated bonds. As answered in another question, last atoms in ...
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144 views

What actually is the Wavefunction?

I am aware that the square of the Wavefunction gives the probability density of finding an electron at a particular point in space. I have also heard that it's a complex number but since it's a ...
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1answer
42 views

atomic mass chemistry chang

there are two stable isotopes of iridium Ir (190.96) and Ir (192.96) if you randomly pick an iridium atom from a large collection of iridium atoms which isotope are you more likely to select ??
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1answer
74 views

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
48 views

Potassium Atom can act as reducing agent, yet ion cannot?

I am currently looking through a revision sheet, however it has caught me on a question 'Explain why a potassium atom can act as a reducing agent yet a potassium ion cannot'. I have done brief ...
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101 views

How can two orbitals constructively and destructively interfere simultaneously?

The molecular orbital theory dictates that when two atomic orbitals form molecular orbitals, then two molecular orbitals must form (i.e number of atomic orbitals = number of molecular orbitals). For ...
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73 views

Which is the bigger ion, F- or O-?

Well, according to the proton-electron ratio $\ce{O-}$ should be bigger than $\ce{F-}$ What about the charge/electron density in $\ce{F}$? Will it not affect the size of the atom of $\ce{F-}$?
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1answer
63 views

Can you calculate the properties of a substance based soley 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 ...
5
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1answer
192 views

How can we measure atomic radius of atom?

The definition of atomic radius is ha;f the average internuclear distance of a atom. But many times it have been told to me that it is not possible to handle single atom, then how can we measure the ...
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1answer
32 views

How does the vacuum in atoms persist?

From very elementary chemistry I understand that atoms are mostly empty space, with a few tiny little objects whizzing around. There must then be a vacuum in between these particles. I always thought ...
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1answer
201 views

Explaining Ionization to kids

I have a quest to explain a physical, chemical theory to kids of age 8-12. The topic is "Ionization". We all understand from early experiments of Physics and Chemistry (the Millikan oil drop ...
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1answer
153 views

Why can't light pass through a gold foil, but alpha particles can?

Rutherfords experiment showed that most of the alpha particles passed through a thin gold foil undeflected. So why can't light pass through the foil, which is supposedly thinner than the heavy alpha ...
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How can two electrons lie together in an orbital?

Two electron of opposite spin can lie in a single orbital.. But what about the electron-electron repulsion. Okay! I got that the nuclear charge rather the large Z-effective overcome this repulsion by ...
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640 views

Difference between actual position of electron and Radial Distribution Probability

Its known that the radius of maximum probability of 2s orbitals is more than that of 2p orbitals. It means that the maximum probability of finding an electron in an 2s is further away from electron ...
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1answer
78 views

Why did Dalton assume that atoms are spherical?

One of the primary components of Dalton's theory is to "express" an atom as an unbreakable spherical shape filled with whatever. The question is, why didn't he suggest any other shape, like for ...
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66 views

Find n and the wavelength too

To start with its a homework problem, quite lengthy. A particle of mass equal to 208 times the mass of electron moves in a circular orbit around a nucleus of charge +3e. Assuming the BOHRs model of ...
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1answer
55 views

Protons or electrons are responsible for chemistry of an atom?

Is the question in a correct form? I can't add anything as a comment. Thank you.
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69 views

Atomic radii of Sc,Ti and Fe,Co

The atomic radii of Sc is 162pm , Ti is 147pm , Fe is 126pm and that of Co is 125pm. Electronic configuration of Fe is (Ar)3d6 4s2 and that of Co is (Ar) 3d7 4s2. Difference of Z between them is 1 ...
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1answer
123 views

Why Aren't Chlorides Of The Noble Gases As Prevalent As Their Fluorides?

I can't find the answer to this question on this SE website, and I apologize for the repetition if it has been answered before. It is my understanding that compound formation has only been observed ...
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2answers
96 views

What happens when we heat an atom?

Question is simple.. If we take an atom of any element and then supply heat energy to it then what will happen? Acc to me in beginning energy[quanta(due to excitement of electron and then moving ...
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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
192 views

The definition of formal Charge

Ok, most people including me know that formal charge is just a book-keeping tool. I know how to calculate it, apply it to Lewis structures etc etc. But I am confused in its very basic definition which ...