What is Atomic structure: Definition and 54 Discussions

An atom is the smallest unit of ordinary matter that forms a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small, typically around 100 picometers across. They are so small that accurately predicting their behavior using classical physics—as if they were tennis balls, for example—is not possible due to quantum effects.
Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. More than 99.94% of an atom's mass is in the nucleus. The protons have a positive electric charge, the electrons have a negative electric charge, and the neutrons have no electric charge. If the number of protons and electrons are equal, then the atom is electrically neutral. If an atom has more or fewer electrons than protons, then it has an overall negative or positive charge, respectively – such atoms are called ions.
The electrons of an atom are attracted to the protons in an atomic nucleus by the electromagnetic force. The protons and neutrons in the nucleus are attracted to each other by the nuclear force. This force is usually stronger than the electromagnetic force that repels the positively charged protons from one another. Under certain circumstances, the repelling electromagnetic force becomes stronger than the nuclear force. In this case, the nucleus splits and leaves behind different elements. This is a form of nuclear decay.
The number of protons in the nucleus is the atomic number and it defines to which chemical element the atom belongs. For example, any atom that contains 29 protons is copper. The number of neutrons defines the isotope of the element. Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals. The ability of atoms to associate and dissociate is responsible for most of the physical changes observed in nature. Chemistry is the discipline that studies these changes.

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  1. H

    I Structural difference between soft and hard ferromagnets

    In the ferromagnetic materials not only the atoms have magnetic dipoles but also the dipoles are aligned well in different domains. However, what is the differnce berween atomic structure of a soft ferromagnet like iron and a hard ferromagnet like a bar magnet? My first guess is that the atomic...
  2. Biele

    Reactivity in Different Groups

    ik this is basic knowledge, that all groups go up in reactivity the further down you go in the group, except for group 7, where this is reversed. however i don't understand why, because in group 7, the electron shielding still increases the further down the group you go, like with all the other...
  3. M

    Seeking books to help me understand the structure of the Hydrogen Atom

    TL;DR Summary: How to learn about the Hydrogen Atom from Level 2 OU Degree I am copleting the second year of the OU physics degree and "understand" what is taught about the Hydrogen atom there, energy levels et al. I am not yet competent in calculus here. I seek a means, buy a book....view...
  4. tbn032

    B Exploring the Alpha Particle-Electron Interaction in Gold Foil Experiments

    My current understanding: The mass of alpha particle is approximately 7340.6 times higher than the mass of electron.in the gold foil scattering experiment the deflection of alpha particle due to electron is approximately zero. The reason that is given is that since the electron is much lighter...
  5. A

    I Atomic Structure: Why Does Energy Decrease with Orbit Number?

    I have read that an electron requires certain minimum energy of threshold frequency to move an orbit However the energy needed decreases with increase in shell number The transition energy is reduced with each orbit For example The energy to shift an electron from 1st to 2nd orbit is much...
  6. Sanborn Chase

    B What Fills the Space Between the Nucleus and Electron Shells in an Atom?

    Summary: The Space Between the Nucleus and Electron Shells? What composes the space between an atom's nucleus and its electron shells?
  7. coolul007

    Magnetism and atomic structure

    Does atomic structure require a magnetic force? I understand that in the world of people it is most appreciated, however, it doesn't seem to have a purpose in the atomic structure.
  8. rxy152

    Atomic Structure problem regarding interatomic spacing

    Homework Statement In a gas of hydrogen under normal conditions, the interatomic spacing is 1.56 × 10^−8 m . Assume the gas is made of atomic, not molecular, hydrogen. For what n-value of the hydrogen atoms is the size of the atom comparable to the interatomic spacing?The value of h bar is...
  9. rxy152

    Atomic Structure- Energy diff between levels

    Homework Statement Consider the NaCl molecule, in which the atomic weights of Na and Cl are 23 and 37, respectively. The internuclear separation is 0.236 nm, and the ”spring constant” for vibrations is k = Mred ω^2 = 1 × 10^9 J/m^2 . Calculate the energy difference between adjacent vibrational...
  10. S

    Free Electrons: Causes of Release Explained

    So, as far as I know free electrons are just electrons that have been 'released' from the shell of an atom and can now move. If this is true, what is it that causes the electron to become free in the first place? Thanks in advance to any answers ☺
  11. Bloopy

    B Doubt regarding Rutherford's Alpha Scattering Experiment and Impact Parameter

    It is mentioned in my Textbook that if alpha-particle has large impact parameter, it gets scattered through small angles and vice versa. I understand that impact parameter is defined as the perpendicular distance between the path of a projectile and the center of the nucleus. I am unsure how...
  12. P

    Ionization Energy of Helium Atom | 24.6 eV

    Homework Statement The energy required to ionize a helium atom is 24.6 eV. The energy required to remove both the electrons from He atom would be?The Attempt at a Solution My textbook says- IP1= 24.6 eV IP 2= IP1*Z2 How can they relate the first ionization energy to the second one? The Bohr's...
  13. W

    B Atomic Structure: Why Don't Protons Repel Each Other?

    If like charges repel each other, what keeps the protons clustered in the nucleus of the atom from separating ? and why wouldn't the electrons with a negative charge pull them out from the nucleus ?
  14. Chaitanya V

    B Atomic Structure: Theory vs Observation

    Does atom really looks and behaves like as that explained in quantum mechanical model? Or is it just a Mathematical Tool to express the observations? Is it like that that scientist were unable to find any clue about real atomic structure and just created a mathematical tools following the...
  15. epenguin

    Elements of truth - Moseley, Bohr, recognition and teaching.

    There is no longer a history section in PDF, but this is not suitable for any speciality forum. Just yesterday*, as usual a step ahead and with uncanny prescience, I was recommending a student to familiarise himself with Moseley's law as reinforcement and more in the learning of atomic physics...
  16. ira

    Modern physics: Atomic Structure

    Homework Statement If we take the average radius of the electron wave function in the ground state of hydrogen to be the Bohr radius, calculate the average potential energy of the electron due to the Coulomb interaction with the nucleus. State answer in eV. Homework Equations I think the...
  17. Ankhen

    B Atomic Structure: Does an Atom Have Matter and Charge?

    Simpel question: does an atom consists of matter and charge? Yes/no?? If no Then what?
  18. eis3nheim

    What is the best referece book to study atomic structure?

    what is the best referece book to study atomic structure and electronic structure of atoms ?
  19. S

    Gold Atom Count in O-Ring: 10.4x10^21

    Homework Statement A golf O-ring is used to form a gastight seal in a high-vacuum chamber. The ring is formed from a 100-mm length of 1.5-mm-diameter wire. Calculate the number of gold atoms in the O-ring. Homework Equations Volume of cylinder = PI*h*r^2 The Attempt at a Solution I got the...
  20. S

    Books on Atomic Structure, Chemical Bonding, Quantum for Beginners

    Hi all! I would like to ask your help! I am a rookie in the subject. I have to admit i don't exactly interested in the mathematical way. I really don't have the "basic" advanced math which would needed it. :) Look at me if i would be a high school physics and chemistry teacher whose imaginary...
  21. S

    Can One Electron Make Two Transitions in a Row?

    Homework Statement Three photons coming from excited atomic hydrogen sample are picked up. Their energies are 12.1 eV, 10.2 eV and 1.9 eV. These photons must come from? A)two or three atoms B)single atom C)three atoms D)two atoms The Attempt at a Solution By solving it i got single...
  22. T

    Question about the atomic structure of insulators

    I'm an apprentice electrician taking night courses. My question isn't a specific mathematical problem. It's a query about a concept. Please let me know if there's a better way/place I can ask it. My text say that atoms can have a max of 32 electrons per shell, with 1-3 being ideal for...
  23. R

    Geometry of the atomic structure

    Hey guys, I was looking at both the time-dependent and time-independent schrodinger equations, and I notice that we often choose to solve these in spherical coordinates. I understand that we do this because they are convenient for problems with azimuthal symmetry. However, how do we know that...
  24. S

    Atomic Structure of Wet Oxidized Silicon

    Hello everyone, I would like to buy some Si wafer with SiO2 layer on it. The manufacturer told me that they obtain the SiO2 with a wet oxidation process. My question is, would this layer be amorphous or crystalline or polycrystalline? Thanks!
  25. P

    General question about atomic structure

    the product of velocity of an electron and the principal quantum number is independent of which variable ? options given : a) velocity b) principal quantum number c) speed of revolution d ) energy of electron I wrote c, is it correct ?
  26. D

    Conceptual question from Atomic Structure

    It is well known that, "Neil bohr failed in his model in which he described an electron as a charged particle moving in well defined circular orbits about the nucleus." However he failed because of the two major reasons.. a) It didn't consider the wave nature of the electrons b) contradicts the...
  27. Jadaav

    Atomic Structure: Uncovering the Nucleon of Chlorine 35.5

    I got a question : Why is the nucleon of Chlorine 35.5 ? Why is is not a whole number ?
  28. Saitama

    How Is the Radius r Related to Quantum Number n in Bohr's Model?

    Homework Statement A small particle of mass m moves in such a way that P.E.=-1/2mk(r)^2, where k is a constant and r is the distance of the particle from the origin. Assuming Bohr's model of quantization of angular momentum and circular orbit, r is directly proportional to: (a)n2 (b)n...
  29. mnb96

    Limits of classical views of the atomic structure

    Hello, this might be a trivial question for many of you. I would like to know what are the simplest phenomena/experiments, if any, (and perhaps the first historically) that contradict the assumption that subatomic particles like electrons, protons, neutrons..., can be thought of as "small...
  30. L

    How does atomic structure relate to how well things share energy.

    Like, let's say substance A, in the sun, is very hot. After the sun goes down, it stays hot, but after awhile it becomes cold. Element B, in the sun, is also very hot, but after the sun goes out, it basically becomes cold immediately. Why is this?
  31. K

    Can gas density be permanently altered and what influences it?

    Can the density of gas be changed for good, or is the change just temporary? And what increases density in gases?
  32. T

    Atomic Structure: Is It Necessary to Assume Orbits Are Circular?

    Please help me in clearing my basic doubt We all know that positive charges are concentrated at the centre of the atom , known as nucleus and electrons revolves around the nucleus in orbits. Is it necessary to assume that orbits are circular ?
  33. J

    PLEASE Help - interpreting an Atomic Structure question

    Homework Statement It commonly happens that the hyperfine structure in a transition is dominated by the contribution of an s-electron in one of the levels. What property of s-electrons could be responsible for this? A transition of this kind occurs at 494nm in singly ionised 133Cs between a...
  34. M

    Electrons' Angular Velocity in Atomic Structure: Examining the Same V?

    In special relativity the clock hands velocity is represented by: V = v0*(1-v2/c2)^1/2 then: What happen with electrons angular velocity in atomic structure? It may be the same?: V = v0*(1-v2/c2)^1/2 if this could be true what happen with matter?
  35. S

    How to find the Atomic Structure of a Constituent

    For a project/idea I'm working on, I need to find the charge density of tap water. I've read that this can be determined by simply subtracting total protons minus total electrons. I've got a list of elements that are in the water, but I'm not 100% sure how to find the exact number of electrons...
  36. J

    Unlocking the Mystery of Atomic Structure

    let me see if I got this one right: By solving the S E for bound system u got the quantum number n l and ml. each set of numbers corresponds to a curtain wave function and electron. One gots fine structure when adding the spin up 1/2 and down 1/2. so every electron in the atom has a set of...
  37. S

    Crazy idea about atomic structure

    Is it generally assumed that there is a smallest building block of matter? Or is it assumed that there is always a smaller particle within any particle? because i was thinking in my calc 2 class the other day... If you have, say, a water bottle on a table, and you assume that there is always...
  38. S

    Optical Spectroscopy and Atomic Structure

    Homework Statement Calculate the energy and radius for each of the five lowest (n = 1,2,3,4,5) electron orbits in a Helium atom with only one electron. Enter the energy as a positive value in units of "eV" and the radius in units of "nm". Hint: The Helium nucleus has 2 protons so Z = 2 and...
  39. S

    Ground state energy in Optical Spectroscopy & Atomic Structure

    Homework Statement I just want to know if there is a relationship between the ground state of Hydrogen which is 13.6 eV and the ground state of Helium. The problem is asking me to find the ground state of Helium, but I am not sure how to go about it. Any advice? Homework Equations...
  40. J

    Atomic structure and determing effective nuclear charge

    Homework Statement The 3s state of Na has an energy of -5.14 eV. Determine the effective nuclear charge. Homework Equations Zeffective = Z - S (not listed in textbook, found this online when trying to figure out the problem) The Attempt at a Solution Nothing in the textbook in...
  41. A

    Atomic Structure: Impact of 663nm Photon on Excited Hydrogen Atom

    If a photon of wavelength 663nm is incident on a hydrogen atom in its fourth excited state(n=5),then A.the atom doesn't absorb the photon B.the atom absorbs the photon but is not ionized C.the atom absorbs the photon and is ionized,with the electron having zero kinetic energy after ionization...
  42. M

    Few simple questions about atomic structure and properties

    Homework Statement a)what property of graphite is the result of the presence of delocalized electrons? b)what is the reason for the generally low melting point of group I A metals as compared with the high melting points of metals in the center of the transition series? The Attempt at...
  43. K

    Optimizing Material Strength: Fact or Fiction?

    Dear experts - I'm writing a novel in my spare time, and would appreciate some help with a little bit of research. Some of the story is set in the distant future, where super strong materials are available. My problem is that I don’t know how to describe these super materials. I want to...
  44. L

    Atomic Structure - help needed

    I need help with these two questions: 1. Electron diffraction can be used to investigate both the arrangement of atoms and the dimensions of nuclei. Explain how changing the energy of the electrons can be used to achieve this. And... 2. Uranium has atomic number 92. Two of its common...
  45. Z

    Atomic structure and classification studies

    Kindly give me a link to some place I can study about Atomic Structure and Periodicity/Classification for IIT-JEE
  46. G

    Atomic spectra and atomic structure by Gerhard Herzberg

    Hi! to everyone on the forum. I am new and did not really know where i should of posted this thread its not homework its just a question i have. A friend of mine asked me a question about a book he read about (atomic spectra and atomic structure by Gerhard Herzberg). Gerhard Herzberg said...
  47. S

    Is Hilbert space an isomorphism with the field of n-dimensional complex numbers?

    I recently made a post here asking questions that where clearly rediculous. I guess I need to be more obtuse. The reason I asked it here is that I'm looking for any possible way in which the 'tornado-like' rotation of galaxies could be explained by any kind of possible atomic structure in 3D...
  48. S

    Question regarding Atomic Structure (orbits)

    I have my doubt,solution and question in the attachment that followed.Thanks for anybody that spend some time on this question.
  49. A

    Understanding 3d Sublevel Filling: Help Needed!

    i still don't understand why when the 3d sublevel is half-filled or completely filled we get : 3d5 4s1 or 3d10 4s1.. I need a real expert to clarify it for me.. Please its urgent. Thanks Joe
  50. T

    Atomic Structure: "Long Range" and "Short Range" Translation

    Hi everyone I missed some content in my lecture about atomic structure of atoms. In the lecture, the lecturer talked something about "slipping" , "easy directions" and "slip systems"...I don't really catch these stuff in this lecture. But I could find these in textbook. What makes me most...