A nucleus made of protons and neutrons surrounded by a cloud of electrons equal in number to the protons.

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If an atom is fully ionized by removing all electrons, is it still an atom?

This is a question about terminology. To me, it's clear that the nucleus of an atom is still an atom. But a comment by Willie Wong at Is nature symmetric between particles and antiparticles? raises ...
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482 views

Why can free lithium atoms not take part in an Auger process?

Shouldn't it be possible for an incoming photon to excite one of the 1s electrons to a 2p state (or one of even higher energy) and then for the excited electron to drop back to 1s and kick out the 2s ...
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Why and how, in QED, can excited atoms emit photons?

The quantum mechanics of the structure of atoms as determined by the electromagnetic forces inside them correctly describes the location and coupling of the different energy levels in essentially all ...
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Is Palladium an exception?

I have been taught in school that atoms cannot have more than 8 electrons in the outer shell. Palladium atom's electron configuration is 2,8,18,18. Why isn't it 2,8,18,17,1 like the case of Platinum ...
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Atomic mass of Copper-63?

This URL lists the mass of Copper-63 as 62.9295975(6) and this other URL lists the mass as 62.939598. These values differ by almost exactly 0.01 which seems hard to explain by experimental error. ...
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Electrical neutrality of atoms

How is it that atoms with equal numbers of protons and electrons are described as "electrically neutral" when the proton is 1,800 times more massive than the electron?
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Is there the smallest particle that can be guaranteed to be unable to be broken down into smaller particles?

Is there the smallest particle that can be guaranteed to be unable to be broken down into smaller particles?
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Open shells in Quantum mechanics of multielectron atoms

This question: How do electron configuration microstates map to term symbols? And the discussion of multielectron effects here: Quantum Computing and Animal Navigation Inspired me to try to understand ...
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Is it possible to bind an entangled electron to the outer shell of an atom or just a proton?

Say we start with an entangled electron--positron pair and we separate them. I want to take the entangled electron and bind it to a proton or the outer shell of an atom. Is it possible to do this ...
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Photon hitting an atom with higher energy than needed to ionize

Suppose we have an atom with several energy levels (e.g. an hydrogen), and it is hit by photons. I know that in order to have the atom change energy levels, the photon must have an energy level ...
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What is in the space between a nucleus of an atom and its electrons?

There is a common analogy about the structure of an atom, such as the nucleus is a fly in the centre of a sports stadium and the electrons are tiny tiny gnats circling the stadium (tip of the hat to ...
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Why does amount of protons define how matter is?

My question might sound convoluted but my mind is twisting right now so my apologies in advanced. Why is it that when I have one proton and one electron it is Hydrogen a clear flammable gas, and ...
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Scaled energy output of a hydrogen atom

I'm trying to get a grasp of the power within a single hydrogen atom (e.g. the power released when whatever process happens in a hydrogen bomb)... If we could enlarge a hydrogen atom up to the size of ...
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How does electron excitation relate to atomic orbitals?

Taking off from the Rutherford-Bohr model, Figure 1. Rutherford-Bohr model. when an electron absorbs energy (from light, heat, or otherwise) it jumps to a higher energy level, or shell. Then when ...
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Why is the relationship between atomic number and density not linear?

What are the factors that affect the density of an atom?
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Effect of Cosmological Expansion at the Atomic Level [duplicate]

Possible Duplicate: Why does space expansion not expand matter? Does cosmological expansion have any effects at the atomic level?
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Zero probability of finding an electron in the nucleus

One and the same electron in a p orbital and taking part in a common ¤Ç (pi) bond has two lobes visualized as connecting through the nucleus. There is however zero probability of finding an electron at ...
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How does electron move around nucleus?

I need to get a nice picture about how electron moves around nucleus? I find concept of probability and orbitals quite difficult to understand?
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Is there a [set of] rules/patterns that apply to elements [duplicate]

Possible Duplicate: Do current models of particle physics explain the chemical properties of elements/compounds? Is there a rule/pattern, or multiple rules and/or patterns, which describe ...
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Why does space expansion not expand matter?

REFORMULATED: I have looked at the other questions (ie "why does space expansion affect matter") but can't find the answer I am looking for. My question: There is always mention of space expanding ...
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Turned to steel in the great magnetic field

This is obviously a "fun" question, but I'm sure it still has valid physics in it, so bear with me. How great of a magnetic field would you need to transmute other elements into iron/nickel, if ...
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Which experiments prove atomic theory?

Which experiments prove atomic theory? Sub-atomic theories: atoms have: nuclei; electrons; protons; and neutrons. That the number of electrons atoms have determines their relationship with other ...
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Appearance of atoms

I was watching a documentary entitled "The Atom" and one of the statements made was that Atoms behave differently when we look at them. I wasn't too sure about the reasoning behind this and i'm hoping ...