Atoms Definition and 880 Threads

What's up everybody, I have a curiosity that struck me today and I figure some people here could probably provide some insight on. Today I was reading the book Broca's brain by Carl Sagan, and in it he pegs the number of atoms in a grain of salt to be around 1018. However, in the same...

As the title states, if I go to space and detect several atoms per square meter of space, does this suggest that the space between these atoms is essentially void of all forms of matter? Thus is this a perfect vacuum?

A balloon contains 0.40 mol of helium at 300K. calculate 1/ The number of Helium atoms in the balloon 2/ The average kinetic energy of the helium atom in the balloon 3/ The total kinetic energy of the helium atoms in the balloon I am having a lot of difficulties to manage the ideal...

Just for fun, I'm wondering if anyone knows what compound has the greatest number of different atoms. Even something as complex as DNA only seems to have five. But in theory you could have a molecule that includes the whole table! Seems like there's not much diversity in ordinary molecules...

I guess I'll take pot luck and ask another question here. I think I read somewhere that the current thinking is that the electron remains as a point or particle, even when it "orbits" an atomic nucleus. Yet I thought that deBroglie's contribution was that the electron is some sort of standing...

I was looking at sulfur hexafluoride and noticed that the sulfur forms 6 bonds with fluorine. Wouldn't 2 bonds put it at 8 valence electrons? How does it form so many extra bonds when it only needs 2? Edit: I should word this as "How does sulfur form 6 bonds with fluorine? Wouldn't that give it...

What happens to the atoms when they collide in CERN? They break down into their smaller parts I believe like glueons and other pieces, but do they stay that way or do they then recombine or what? Also do the same atoms, like 2 gold atoms, when smashed together always produce they same...

I would like to see how far I can get writing some novel & simplified simulator code for molecular modeling based on QM. ------ Background follows ---- skip to next post to get to the details of the project & starter QM question.. My son took chemistry this last semester (High-school...

Hi, Would anyone be able to explain the main differences between the effect of electrons and photons colliding with atoms in the ground state. As far as I understand they are very similar as both cause excitation and in some cases ionization. Any help would be greatly appreciated. Dave

The diagram (see attached) represents some of the energy levels for an atom of a gas. White light passes through the gas and absorption lines are observed in the spectrum. Which electron transition produces the absorption line corresponding to the lowest frequency; A. E3 to E2 B. E2 to E3 C...

Hi all,well my first questions, such a huge community, thanks to the admin/staffs for this making this forum :) How did the Hydrogen Atoms formed from the energy in the early universe ? like our DNA determines how we are built (just a sample approach), was there in the energy any...

According to my knowledge and understanding of things, mirrors reflect light perfectly because they are almost perfectly flat, or at least uniformly flat at most places. (\ and / are light rays) __\/__ But if all matter is composed of atoms, then a mirror would not be flat and would...

Do physicists say that atoms behave as waves just because they can't look at them directly so they have to use math to predict probable areas where they could be? or do atoms literally behave as waves?

Homework Statement How many atoms are contained in 15 litres of Ar at STP Homework Equations The Attempt at a Solution I just did 15/22.4 = 0.669642 0.669642 x 6.022x1023 =4.0325x1023 Is this correct. Thanks so much for your helo

Homework Statement 1. Homework Statement The temperature of the surface of a certain star is 8000 K. Most hydrogen atoms at the surface of the star are in the electronic ground state. What is the approximate fraction of the hydrogen atoms that are in the first excited state (and therefore...

musings on penning traps and geonium atoms ... so, last night at the bar, i got into a long, unwanted conversation with somebody about their plan to create an "antigravity" machine. to gauge his intelligence about *actual* physics, i asked him if his antigravity machine was also a perpetual...

I have a question which may seem stupid, but I think I missing something here. I see 2 equations describing allowed energies for electrons in hydrogenic atoms, being: E = -\frac{hcRZ^2}{n^2} And E = -\frac{RZ^2}{n^2} I assume that both are correct, but what makes the difference? Is it the...

I wonder if there is any theoretical knowledge how to predict which atoms will decay first in given radioactive substance? I was asking about this in school and teacher said it is not possible to predict this...i doubt this process is random... Thanks

Hi People all know that a neutral atom has no net charge. Well, does that mean that it neither creates an electric field nor is affected by any electric field? I wonder whether it's correct or not, because the distance between a test charge outside this atom is closer to its electrons...

Help with a debate on atoms at work? Hey all, For the last few hours we have been debating whether our bodies in reality are 99.999999999999% and so on empty space. I have studied physics at GCSE, A-level and University so I'm well aware that atomic nuclei are roughly 10^-15 meters and an...

I have a surface (paraffin) and a vapor of atoms (alkali). When atom get the wall, it is sticked for some time, exchange it energy and momentum with wall and then release. I want to know the atomic velocity distribution (both in directions orthogonal and parallel to the surface) after atom...

This thread is intended to ask the question about potential future sources of energy to experts, explain a few things and generate discussion about the future of energy and it's possible uses. Nuclear power is great. But it requires a bulky apparatus and very specific materials. Perhaps...

Question: A hydrogen atom has one electron. If we heat hydrogen gas up enough, we will completely separate each electron from each hydrogen atom (called "ionization"). What will the spectrum of ionized hydrogen look like ("ionized" means that the electron has already been taken away)? Here's...

Hello, does hydrogen atom with a single electron have p orbitals? when the single electron of the hydrogen atom is excited, can it go to the 2p orbital? are "p orbitals" consequence of electrons interacting with nucleus ( protons ) ? or are "p orbitals" consequence of electrons interacting...

Hello. I have a non-stoichiometric reaction that balances out to: C12H23.4 + 12.265(O2) ---> 11.7(H2O) + 6.415(CO2) + 5.585(C) The problem started with the compound C12H23.4 which is the published formula for a high-grade kerosene of the form CnH1.95n. So, in the beginning, there...

Homework Statement The atoms in a gas can be treated as classical particles if their de Broglie wavelength is much smaller than the average separation between the particles. Compare the average de Broglie wavelength and the average separation between atoms in a container of (monoatomic) helium...

I have been reading about the Stern–Gerlach experiment and found that the atoms leaving the oven in the experiment have an average energy of 2kT, rather than an energy of 3kT/2 for a gas. I can not find a reason for this higher energy myself and would like suggestions on why this seems to be...

Homework Statement Calculate the total number of atoms in 2g of oxygen gas Homework Equations molar mass no of mole The Attempt at a Solution I try to solve that by following steps but i don't know correct or not. in fact, i am so confused with mole no of mole: 2 / 16x2 mol...

Could someone please explain to me as to why the binding energy per nucleon is lower for atoms of low mass number as compared to the atoms in the middle zone of the binding energy per nucleon versus mass number graph? My conceptual issue lies in the fact that when the mass number is low the...

Homework Statement 1.If protons and two neutrons are removed from the nucleus of an oxygen-16 atom, a nucleus of which element remains? electron 2. If an atom has 43 electrons, 56 neutrons and 43 protons what is its approximate atoms mass? What is the name of this element? Technetium, 99...

Could anybody explain to me why it is that atoms desire (sorry about the personification) a lower energy state? It just occurred to me as I was studying enthalpy changes at school...

Could anyone give me a couple of sentences to what it is?

Straight forward question. What would prevent the process of a giant lump of neutrons from forming a stable nucleus?

Homework Statement If you were to count the number of carbon atoms at the rate of four each second, how long would it take you to count 6.0 grams of Carbon atoms? Homework Equations ---- The Attempt at a Solution 6.0 g Carbon x [1 mole carbon atom / (6.02 x 10^23 grams )] = 9.97x10^-24...

Homework Statement A cubic centimeter of water has a mass of 1.00g. How many molecules does it contain? How many atoms are in 1.00g ice cube? Homework Equations 1 mole=6.02 x 10^23 molecules(or atoms) 1 mole of H20= 18g The Attempt at a Solution The answers are: 3.3 x10^22...

I encountered a question in my book: a)An electron is trapped in a solid between a group of atoms where the potential is +2.8V The de Broglie wavelength of this electron is 1.2nm. Calculate i) its speed ii) its kinetic energy iii) the sum of its kinetic energy and its potential energy b)i)...

In wikipedia, I read about BEC. so I just wonder in that articles, so I write in this page. Adopt that article, " They did this by cooling a dilute vapor consisting of approximately two thousand rubidium-87 atoms to below 170nK using a combination of laser cooling and magnetic evaporative...

Why is it that when two hydrogen atoms combine together, their combined energy is less than the energy of one hydrogen atom by itself? Why wouldn't the combined energy be twice as much?

"verify that the number of atoms..." Avagadro's constant Homework Statement One mole of a substance is defined as an amount, in grams, numerically equal to its molecular mass expressed in amu. (when we refer to a chemical element and not a compound, we use the atomic mass.) Verify that the...

Isn't the distance between two atoms where nothing exists, no atoms or subatomic particles, absolute vacuum? a place where nothing exists?? I am not too educated in such physics, so please do explain what you say

Homework Statement An oxygen atom is four times as massive as a helium atom. In an experiment, a helium atom and an oxygen atom have the same kinetic energy. What is the ratio vHe /vO of their speeds? Homework Equations K=.5mv2 The Attempt at a Solution...

Hi guys i have a rather weak concept on circular motion so i wish you guys can help me. As you know when something goes round in circle, there is a net force towards the center right? If that is the case, why this force doesn't push the particle to the center causing it to spiral towards the...

Hey. I got a locked configuration of atoms, that is there positions are fixed. I would like to calculate the energy of this configuration and also the electron density. I've looked around on the internet and in some books and found that maybe Density Functional Theory (DFT) is the answer. If...

I know this question is fairly easy, but I'm completely flabbergasted by it. I'm sure it has to do with the Ionization energy, I'm just really confused by the negative values for the binding energies. Anyway here is the question. The absolute value of the binding energy of the outermost...

Homework Statement The dissociation energy of a hypothetical molecule AB (composed of A+ and B- ions) is 5.24 eV, and the equilibrium separation of AB is 0.216 nm. The electron affinity of a B atom is 3.36 eV and the ionization energy of element A is 4.00 eV. Determine the core-repulsion...

Homework Statement Consider two different two-dimensional arrangements, (a) and (b), of four atoms (just four!) defined as follows: (a) in which the centres of the four atoms form a square of side a_0 (b) in which the centres of the atoms form an equilateral diamond shape with angles...

I only have one example that I can find, and that's finding the diameter of a copper atom. Do most elements follow these steps? 1.) Make sure density is in kg/m^3 2.) find number of copper atoms in a 1 meter by 1 meter cube. 3.) find number of atoms in one edge(row?) of said cube. 4.)...

1. Calculate the velocity dispersion for hydrogen atoms in the solar photosphere, which has a temperature of 5800 K. 2. I know no equations to solve the problem. 3. I have no idea any method of going about solving for velocity dispersion. I would appreciate any guidance. Thanks

Homework Statement For the molecule ICl3 I) How many lone pairs of electrons are on the central atom? II) How many other atoms is the central atom bonded to ? III) What is the molecular geometry of the molecule? IV) What is the electron-pair geometry? a) triangular planar b)...

Why are all atoms in constant motion? It is just a fundamental phenomena of our world? Can someone explain the theory behind this? Why does decreasing/increasing the "temperature" affect the speed (kinetic energy) of atoms? Again, can someone explain the fundamental theory behind this?