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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Placing the atomic mass and number of an element… [on hold]

Why are the atomic and the mass numbers of an element flipped in the textbooks relative to the periodic table?
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What is there in an atom between the nucleus and electrons?

As you can see the atom consists not only of the nucleus and electron but also of "empty space is the space empty or is their something else?
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36 views

Atomic number $Z$

If electrons were spin-$\frac {3}{2}$ instead of spin-$\frac {1}{2}$ , what would be the atomic number $Z$ for the first noble gas ?
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Why does ionization energy increase as we go from left to right in a period?

Why does ionization energy increase as we go from left to right in a period? In my textbook, the explanation is as follows: "This is consistent with the idea that electrons added in the same ...
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Interaction radius of a molecule

What is the most commonly used radius of an atom or molecule to describe the area that must touch another area of another molecule for the two to react. Is there one radius that always works or does ...
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137 views

Usefulness of the outdated Bohr model?

Whilst the Bohr model is incomplete and incorrect, it had limited usage in predicting spectral lines. In the same way, could it possibly with limited accuracy, be used to predict the outcome of ...
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Aluminum foil in copper chloride solution

What is a physical change when Aluminium is put into Copper (II) Chloride. I know it is a chemical change but are there any physical changes
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How was it determined that the electron observed in the cathode ray experiments was the same particle that gave an atom its balancing negative charge?

How was it determined that the electron observed in the cathode ray experiments was the same particle that gave an atom its balancing negative charge? Couldn't there have been an entirely different ...
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38 views

Diatomic Molecules/Elements

What is the difference between diatomic molecules and elements? Also, If oxygen is element of a single atom, then what makes it a diatomic element? But, then I read that a single oxygen atom can ...
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331 views

Why are so many wave functions associated with hydrogen?

According to Wikipedia, there's an infinite set of possible wavefunctions (orbitals) for the hydrogen atom: $$\psi_{n\ell m}(r,\theta,\phi) = \sqrt {{\left ( \frac{2}{n a_0} \right ...
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How do atoms combine? [closed]

Do atoms combine with the nearest atoms possible because of lower delta E (less energy needed to form a stable nucleus)?
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85 views

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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Isn't the mass of a carbon 12 equal to a mass of 6 neutron + 6 proton + 6 electron?

The mass of Carbon 12 is 12u from definition, and is formed with 6 neutron, each with 1.0087u, 6 proton, each with 1.0072u and 6 electron, each with 0.0005u, which all add up to 12.0894u. why is there ...
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Absolute Masses Of Atoms (in Kg)

I understand that true (non-relative) masses of atoms are calculated with a mass spectrometer. using this relationship: Centripetal Force = Force due to magnetic field(B) But i was wondering how ...
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Correlation between crystal structure and underlying atomic properties

Can the crystal structure of an element/metal be explained by any underlying atomic or quantum mechanical properties of the element or is it an intrinsic property by itself (like atomic number)?
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47 views

Can we make Gold in a Lab? [duplicate]

Can we make Gold in a Lab? Is it possible to make changes in metals that will create Gold? and How? I have tried to search something related to this but didn't get any good results. Thanks in Advance
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Does Uranium ore count as a mixture?

I'm doing an assignment where we must research the separation of a mixture to obtain a useful final product. I thought about the separation of Uranium from its ore after it has been mined, but I did ...
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117 views

Do multielectron atoms have nodes?

For hydrogen, other than in the 1s state, the electron wavefunctions have radial and/or angular nodes where the electron probability density is zero. In helium or further atoms with more than one ...
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Density Functional Theory with Generalized Gradient Approxmations (GGA) - What Happens if the Electron Density Shows a “Kink” at the Ion Position?

My question may be stupid, so please correct me if you find anything which is obviously erroneous. In the following I will place a question mark (?) besides points/steps I consider doubtful. My ...
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Signs of Exchange and Correlation Potentials

The exchange and correlation potentials refer to those defined in density functional theory. (See also http://en.wikipedia.org/wiki/Local-density_approximation) Define the exchange potential as ...
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Electron Configuration of an element with no. of electrons > 18

Let's say that we have an element, say $\ce{Ca}$. According to law, the last shell should contain only upto 8 e-. Hence, electronic configuration of $\ce{Ca}$ would be 2,8,8,2. But, according to the ...
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Molecular Assembly Program

I'm not totally sure which Stack Exchange community this would go in, but Chemistry seemed best. I've been thinking for a long time now, that it would be cool to have a program where you could design ...
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Is the atom the smallest particle, which takes part in chemical reactions?

According to modern atomic theory, the atom is the smallest particle which can take part in a chemical reaction. But during the formation of hydronium ion, $\ce{H+}$ ion reacts with $\ce{H2O}$ to form ...
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3answers
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Why do no known atoms have electrons in the g or h subshells?

I'm learning about orbital quantum numbers. While checking several elements on the periodic table I noticed that there aren't any atoms that have electrons in the g or h sub-orbitals. Why is this?
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Atomic mass ratios - Is the problem providing enough info?

1 gram of Hydrogen reacts with exactly (almost) 8 grams of oxygen to produce $\ce{H2O}$. 1 gram of Hydrogen reacts with 16 grams of Oxygen to produce $\ce{H2O2}$ can ratio $m_O/m_H$ be determined from ...
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“Editing” atom nucleus

First of all. I am really bad at chemistry and all that. So this might or more likely will sound at least primitive... But this question has been bothering me for far too long. So, I was reading about ...
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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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Why does ionization violate the stable or lowest energy rule in atoms?

Electrons that fill orbitals always do so in such a way that the resulting structure has the lowest energy state possible, though there are anomalies like chromium and so on. But ionization no ...
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Temperature of an atom

I read somewhere that the temperature of an atom is not defined. The definition of temperature is only for larger systems. Why is this so?
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Why neutrons are neutral?

If electrons have a negative charge and protons have a positive charge then how come neutrons have zero charge without consisting of protons and electrons ? (Excuse my bad English)
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How are nuclei stable?

We all know that the density of the nucleus is very high. Nuclei are made up of protons and neutrons, and while protons have the same charge, they are closely packed in a nucleus. How does the ...
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Electronegativity and HCl and HF molecules

In a book I am reading, it is said In the $\ce{HCl}$ molecule, the shared pair of electrons spend more time nearer the chlorine atom. In the $\ce{HF}$ molecule, the shared electrons spend more ...
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379 views

Would there be a difference if deuterium is embedded instead of protium (regular hydrogen) in acids?

So instead of regular hydrogen, it would be a deuterium (still a Hydrogen). For example, instead of $\ce{HCl}$ it would be $\ce{DCl}$ where D is a deuterium.
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Why is O2 enough to form a mole of Oxygen? [closed]

I understand that this is the most basic knowledge of moles, however I'm still unsure - according to easy research, $\ce{O2}$ forms a mole of Oxygen. As a mole is $6.022*10^{23}$, exactly what on the ...
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electron affinity and electron gain enthalpy

Can anyone help me to clarify the difference between electron affinity and electron gain enthalpy? For example- Why is second electron affinity of oxygen greater than that of sulphur? I think it ...
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It is said that atoms cannot be created. If so, then how did atoms get created after the Big Bang? [closed]

I read somewhere that atoms cannot be created. If this is true, then how did the atoms form after the Big Bang? Also, does this mean that the number of atoms in our universe has remained the same ...
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1answer
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Why should the redox reaction happen between the copper ions and iron atoms?

I know that when $Cu$$^+$$^2$ ions react to $Fe$ atoms, it becomes $Cu$ + $Fe$$^+$$^2$. My question is, why? Copper atoms normally have 29 electrons. These means that in the K-shell there are 2 ...
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Why was atomic mass scale changed from Oxygen - 16 to Carbon - 12?

Why was unified atomic mass scale introduced and why was Oxygen - 16 replaced by carbon - 12 for standardizing atomic scale?
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How was the diatomic nature of many common gaseous elements originally determined?

How did scientists find out that $\ce{Cl2, H2, O2}$ atoms have a two-atomic molecular structure ?
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First ionization energy of hydrogen molecule

If we have the dissociation's energies of hydrogen molecule $H_{2}$($D_{0}$) and the corresponding molecule ion $H_{2}^{+}$ ($D_{1}$) together with the first energy of ionization of hydrogen atom ...
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Is it likely that increased understanding of quantum physics will change our understanding of chemistry?

Reading that the large hadron collider will be up and running with twice as much energy in March 2015, I was curious whether our understanding of subatomic particles has changed our understanding of ...
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Why six C atoms are usually seen in cyclic compounds?

When it gets to Carbon-based molecules, one very possible structure when there are more than six C atoms is the hexagon; though not mostly perfect, it emphasizes that six Carbon atoms tend to bond ...
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What do atoms look like?

A professor of mine noted that when he was in school, microscopes weren't powerful enough to resolve certain things (I forgot what it was). But current microscopes are powerful enough. Extrapolating ...
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What is the reason behind choosing the specific elements used for the synthesis of heavier elements?

Attempts to synthesize still undiscovered elements This is derived from the wiki page: "extended periodic table" and is one of the many examples d or f block elements are used in ...
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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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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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532 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; even in some cases it ...
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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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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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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 ...