# Tag Info

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There is no such thing as classical motion of an electron in an atom. The quantum states electrons in an atom are in are atomic orbitals, which possess a definite energy, but not a definite position. The Bohr model of the electron, in which electrons are thought of as classical particles orbiting the nucleus, is false. The question whether or not two ...

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Why don't electrons collide among themselves Because they aren't anything like billiard balls. Check out the wave nature of matter. And take a look at the Wikipedia atomic orbitals article: "The electrons do not orbit the nucleus in the sense of a planet orbiting the sun, but instead exist as standing waves". The Heisenberg principle states that we ...

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If I understand your questions correctly: Yes, it can be somehow the other way around. But we do "know": There are two sort of particles in here, one of them has a certain charge and is light, the other has the opposite charge and is heavy. You can then claim that the heavy ones rather stay in place and the light ones sprint around and make up the current. ...

0

Generally it is said that current is due to the flow of electrons; how can we make this claim? If the wire is in a magnetic field the moving charges will move in a circle based on the magnetic force. This happens until enough charge imbalance develops on the edges of the wire to produce an equal and opposite electric force. But measuring the voltage ...

1

From classical models, the electron and a proton revolve around their mutual center of mass, which approximately lies on the proton itself, because the proton has a significantly higher mass than the electron. This is why electrons revolve "around" the proton, and hence form the outer layer of an atom. Quantum mechanically, electrons could never form a ...

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The metal plate is typically attached to a circuit which collects the ejected electrons making the system net neutral overall just with a current flowing. Also they are usually more easily ejected because the plate is at a potential attached to a battery. However, if the plate were suspended by an insulator in a vacuum and it continuously lost electrons ...

3

When you say: we can see an individual atom with visible light you need to clarify what you mean by the word see. As you say, there is no problem detecting that an atom is there because we can measure the light it emits, however it will appear as a point source and we cannot use the light to measure its size or shape. To measure the size and shape of ...

2

Oil drop on liquid is about the simplest I think, - take a bowl of still water - dust it with some fine powder - put a small drop of oil of top - The oil spreads out over the surface and generally forms a circle the size of which you can see from the dusting. The thickness of the drop on the liquid can be calculated if you can estimate the volume of your ...

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About the question ,(case 1)Is it that You actually believe that matter is made of atoms in theory and just want to cross check with a simple practical experiment? or (case 2) You actually doubt the existence of atoms itself and want to check it out with an experimental proof. (case 1) Take a flask/container with an attached barometer and fill it with a ...

6

To show kids atoms in action I use Brownian Motion similar to what Robert Brown did with his pollen grains. You need a microscope with at least X400 magnification, some whole milk, a glass slide and cover slip. Place a drop of milk on the slide and a drop of water. Cover the milk-water with a cover slip and view under the microscope. For a whole class it's ...

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Brownian motion would be considered pretty good evidence of atoms. Originally, Brown observed pollen grains moving in water in ways that could not be explained otherwise. 78 years later, Einstein came up with a theoretical model of Brownian motion1 that was later borne out by experiments by Jean Perrin (see this). A translation of Einstein's paper is ...

5

Chemistry. The things we call "atoms" are chemical objects, different of the atoms of the ancients (closer to "elementary particles"). The existence of chemical atoms implies integer proportions in chemical reactions. I'd vote for electrolysis of water. The volume of $H_2$ and $O_2$ increases in integer proportion 2:1. EDIT: from discussion in the ...

0

As stated, helium is inert, so it will not form compounds with other elements. In addition, once it is freely released into the atmosphere, it will quickly rise to very high altitudes, and I assume that it would be stripped away by the solar wind. Despite this, I don't anticipate running out of helium in the near future. Helium is a small constituent of ...

1

I'm no expert in this specific area, but there goes my answer: Helium has neutral net charge and a spherically symmetrical electron distribution. It is in the "noble gases" family in the periodic table, therefore it interact very weakly with other atoms, and it does not bond easily. Due to its charge neutrality, I would guess that Helium suffers almost no ...

4

For a 6 year old, you might want to focus on thickness instead of length, as the numbers get too big with length. A ream of paper (500 sheets) is a bit over an inch thick, say $3.5 \, \text{cm}$, so one sheet is $3.5/50 \, \text{mm}$, or $.07 \, \text{mm}$, which is $7 \times 10^{-5} \text{m}$. An atom has diameter $0.1 \, \text{nm}$ to $0.5 \, \text{nm}$ ...

5

A typical atom is roughly a few times $10^{-10} \text{m}$ wide. A piece of paper is say $(1/4) \text{m}$ wide. Therefore the ratio of the width of an atom to the width of a piece of paper is around $10^9$. A piece of paper is roughly the same width as a human, so $10^9$ is also a rough guess for the ratio of the width of a human to the width of an atom. The ...

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