What is Atomic model: Definition and 30 Discussions

Atomic theory is the scientific theory that matter is composed of particles called atoms. Atomic theory traces its origins to an ancient philosophical tradition known as atomism. According to this idea, if one were to take a lump of matter and cut it into ever smaller pieces, one would eventually reach a point where the pieces could not be further cut into anything smaller. Ancient Greek philosophers called these hypothetical ultimate particles of matter atomos, a word which meant "uncut".
In the early 1800s, the scientist John Dalton noticed that chemical substances seemed to combine and break down into other substances by weight in proportions that suggested that each chemical element is ultimately made up of tiny indivisible particles of consistent weight. Shortly after 1850, certain physicists developed the kinetic theory of gases and of heat, which mathematically modelled the behavior of gases by assuming that they were made of particles. In the early 20th century, Albert Einstein and Jean Perrin proved that Brownian motion (the erratic motion of pollen grains in water) is caused by the action of water molecules; this third line of evidence silenced remaining doubts among scientists as to whether atoms and molecules were real. Throughout the nineteenth century, some scientists had cautioned that the evidence for atoms was indirect, and therefore atoms might not actually be real, but only seem to be real.
By the early 20th century, scientists had developed fairly detailed and precise models for the structure of matter, which led to more rigorously-defined classifications for the tiny invisible particles that make up ordinary matter. An atom is now defined as the basic particle that composes a chemical element. Around the turn of the 20th century, physicists discovered that the particles that chemists called "atoms" are in fact agglomerations of even smaller particles (subatomic particles), but scientists kept the name out of convention. The term elementary particle is now used to refer to particles that are actually indivisible.

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  1. R

    B What happens to excess energy when an electron gets excited by light?

    Hello, I am struggerling with this very basic physics problem. I understand that an electron can get excited if the energy of an incident photon is enough to jump to a higher band. If I understand correctly, this will only use up exactely the required energy. What I do not understand is what...
  2. scythe327

    B Can a hypothetical atom be made out of positrons and electrons ?

    I am a Computer Science Engineering student at a local university in India and I was really moved by the CERN youtube channel and it got me curious about the particles like electrons and protons, I love symmetry in nature and was not a huge fan of proton being nearly 2000 times the mass of...
  3. Gabrielmonteiro

    I On the Rydberg Constant and the Emission Lines

    With regard to Rutherford's atomic model, and Rydberg's discovery in general for the hydrogen distribution lines, what does Rydberg's constant physically mean? Its unit is m ^ -1, as if it were a rate, but it was not clear to me its physical meaning. And why does it grow with atomic mass...
  4. JackFyre

    B Clarification about Bohr's atomic model

    Hey guys! Not a brain scratcher as such, just a clarification. When we talk about Bohr's postulates for his atomic model, would the Bohr-Bury scheme be involved in it? like in his postulates?
  5. J

    I am here to get more clarity on the current atomic model

    For work I am a technical support engineer, who solves all sorts of customer problems. I do physics for fun, not for living. From J.J Thomson 1904, to Rutherford 1911, Bohr 1913 and Mulliken 1932 the atomic model underwent four major changes (including its creation) The more I read and learn...
  6. M

    Studying Learn Quantum Physics: Bohr's Atomic Model

    I am trying to learn quantum physics on my own and while doing this I came across bohr's atomic model. What parts should I focus on the bohr's atomic model so advancing to schrodinger's equation will be easy?
  7. P

    B Question on the Bohr atomic model and energy

    Let's say there are three states ofor energym, E1, E2 and E3, and the electron is at E1, what happens if a photon has energy E > E2-E1 ? Does it interact to the electron anD take it to E2 and the photon loose energy E2-E1 or it doesn't interact at ALL? I mean, the electron can't have an energy...
  8. B

    B Why are there only two colorful metals?

    I think there are only two metals, Copper and Gold , that exhibits some color other than silver or gray. I went to a science exhibition where samples of almost all metals where kept, I think I could only see Copper and Gold having different colors. Why is it so ? why not other metals show colors ?
  9. N

    Bohr's atomic model and Bohr and Rydberg equations

    Hello, well, I am totally new to this section of physics so my question may sound ridiculous, but here it is: When I was reading about the Bohr's atomic model, I learned about the Bohr and Rydberg equations (E=-2,18*10^18*Z^2/n^2 J and 1/λ=RZ^2(1/n1^2-1/n2^2) as well as their proofs. Then I...
  10. C

    Atomic Model of Hadrons mass of excited particles

    So in a lecture I'm reading up on we are given questions to answer during the lectures with no answers, and for this particular lecture the answer has been omitted and it is in none of our textbooks. But basically it says that a proton and a sigma plus, both have the same quark composition...
  11. adoion

    Exploring Niels Bohr's Atomic Model

    hi, ive got a really simple question. niels bohr proposed a model of the atom in witch the electron cannot fall into any energy state but must fall be in certain discreet values and this helps explain why the electron doesn't clumb with the nucleus almost instantly. not the atom needed to...
  12. J

    Atomic Models: Overlapping N Levels & Possible Alternatives

    Have atomic models been proposed that do not have overlapping N levels?
  13. J

    Free-fall atomic model: Bohr with magnetic corrections

    We still often meet Bohr classical atomic model, e.g. for nearly classical Rydberg atoms. However, this model ignores the fact that electron has very strong magnetic moment: is tiny magnet (it wasn't known when Bohr introduced his model). To understand why there are needed corrections, let us...
  14. D

    Question regarding Rutherford's atomic model

    Homework Statement I am basically wondering how they got to the assumption that the Ve = 2Vα. I've tried it a few times and I keep on getting that based off of their other assumptions, Ve should =0, even though I know that this cannot possibly be the case. Homework Equations Conservation of...
  15. D

    Rutherford's atomic model 's limitation

    In Rutherford's atomic model, electrons are in circular orbit around nucleus. My teacher said, "It has limitation. According to classical electromagnetic theory, the electrons are acceration and they will emit radiation and lose energy. And finally spiral into nucleus. Th atom will collapse if...
  16. P

    First Bohr Radius - Quantum and Atomic Model

    Homework Statement Suppose an electron was bound to a proton, as in the hydrogen atom, but by the gravitational force rather than by the electric force. What would be the radius of the first Bohr orbit? Homework Equations r = h^2 / 4∏^2*mke^2 The Attempt at a Solution I'm not...
  17. M

    How does Rutherford's Atomic Model explain energy loss in revolving electrons?

    I studied it in a book that Rutherfords Atomic Model was Unsatisfactory bcz the revolving electrons in his model would lose energy.How would they lose energy as far as I know they are kept in rotation by the centripetal force and work done by centripetal force is 0.NO work done no energy...
  18. S

    Nuclear Atomic Model: Definition & Overview

    What is meant by nuclear atomic model?
  19. T

    Question about Rutherford atomic model

    Rutherford postulated that the electrons are moving around the nucleus of the atom in circular trajectories, right? My professor said that or I believe in it or there is no more chemistry to study, because this does not agree with some law of Maxwell's theory of electromagnetism. He said...
  20. Shackleford

    How Do We Calculate Electron Speed and Radial Acceleration in Atomic Models?

    Calculate the speed and radial acceleration for an electron in the hydrogen atom. Do the same for the Li++ ion. v = e (4pie0mr)^(-1/2) ar = (v^2)/r r ~ 10^-10 m v = 2.24 x 10^6 The book makes note that we can allow a nonrelativistic treatment since the velocity ~ .007c. And for the lithium...
  21. F

    Understanding the Atomic Model: Exploring the Size and Structure of Atoms

    Hi, I always heard the textbook presenting the idea that atom is mostly compose of space by giving the analogy that if the whole atom is the size of a stadium then the nucleus would be the size of an eraser in the middle of a stadium, and the electrons flying around the stadium but if this...
  22. W

    Why J.J Thomson use gold in his experiment for atomic model?

    any can answer this? that why J.J Thomson strike gold by alpha particles in his experiment by which he propose model for atomic structure?
  23. R

    Explaining Hydrogen Atom's Line Spectra: The Rutherford Atomic Model

    Why the rutherford atomic model can't explain the line spectra of the hydrogen atom?
  24. O

    How Does Bohr's Atomic Model Address Electron Energy Loss?

    [b]1[ Now in the 2nd year of b.tech I, since was in class 9th not understanding how Bohr modified the earlier Rutherford atomic model.It is known to me that Rutherford atomic model was failed because it could not satisfy the electromegnetic principle,according to which an elecltron continue to...
  25. B

    Problems with Bohrs atomic model

    May someone please explain what were some problems with the Bohr model of the atom. I found a few things on Wikipedia, but I being a beginner in the Physics curriculum do not fully understand how it all ties together. If there is a link to this topic in the forums, please do tell. Thanks.
  26. G

    How Do Electrons Avoid Spiraling into the Nucleus in Rutherford's Atomic Model?

    Ok, I just posted this in the advanced forum, but looking at some of the topics on there my question might belong in here instead.. I understand Rutherford proposed that electrons orbit around a central nucleus. However, since accelerating charges produce electromagnetic radiation, the...
  27. G

    The instability of Rutherford's atomic model

    I understand Rutherford proposed that electrons orbit around a central nucleus. However, since accelerating charges produce electromagnetic radiation, the orbiting electron should lose energy via E&M and spiral into the nucleus. But my question is: How do I calculate the time it takes for the...
  28. P

    Exploring the Atomic Model Since Quantum Revolution

    Hello, I have a few questions concerning what the atomic model currently "looks like" since the quantum revolution. I know that, since the wavefunction, electrons are in probability "clouds" and I know they are standing waves. So this would mean, technically speaking, that the electron...
  29. T

    Bohr's Atomic Model: Magnetic vs Gravitational Force

    My physics teacher told me that one of the innacuracies of Bohr's Atomic Model is that the nucleus (positive) would attract the electron (negative) making it move as a spiral until it collapses with the nucleus. What I don't get is why the same thing doesn't happen with a planetary system. How...
  30. O

    Bohr's Atomic Model: Exploring Differences & Effects on Spectra

    I need help with these 3 questions: 1. Describe the Bohr model of the atom. How does it differ from a planetary model based on classical physics? ======================== 2. In terms of the Bohr theory why is that electrons don't spiral into the nucleus? ======================== 3. If...