A report on Atom, Proton, Ernest Rutherford and Atomic nucleus

Atoms and molecules as depicted in John Dalton's A New System of Chemical Philosophy vol. 1 (1808)

The quark content of a proton. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons.

A model of the atomic nucleus showing it as a compact bundle of the two types of nucleons: protons (red) and neutrons (blue). In this diagram, protons and neutrons look like little balls stuck together, but an actual nucleus (as understood by modern nuclear physics) cannot be explained like this, but only by using quantum mechanics. In a nucleus that occupies a certain energy level (for example, the ground state), each nucleon can be said to occupy a range of locations.

The Geiger–Marsden experiment:
Left: Expected results: alpha particles passing through the plum pudding model of the atom with negligible deflection.
Right: Observed results: a small portion of the particles were deflected by the concentrated positive charge of the nucleus.

Ernest Rutherford at the first Solvay Conference, 1911

A figurative depiction of the helium-4 atom with the electron cloud in shades of gray. In the nucleus, the two protons and two neutrons are depicted in red and blue. This depiction shows the particles as separate, whereas in an actual helium atom, the protons are superimposed in space and most likely found at the very center of the nucleus, and the same is true of the two neutrons. Thus, all four particles are most likely found in exactly the same space, at the central point. Classical images of separate particles fail to model known charge distributions in very small nuclei. A more accurate image is that the spatial distribution of nucleons in a helium nucleus is much closer to the helium electron cloud shown here, although on a far smaller scale, than to the fanciful nucleus image. Both the helium atom and its nucleus are spherically symmetric.

The Bohr model of the atom, with an electron making instantaneous "quantum leaps" from one orbit to another with gain or loss of energy. This model of electrons in orbits is obsolete.

Proton detected in an isopropanol cloud chamber

The binding energy needed for a nucleon to escape the nucleus, for various isotopes

Protium, the most common isotope of hydrogen, consists of one proton and one electron (it has no neutrons). The term "hydrogen ion" implies that that H-atom has lost its one electron, causing only a proton to remain. Thus, in chemistry, the terms "proton" and "hydrogen ion" (for the protium isotope) are used synonymously

Lord Rutherford's grave in Westminster Abbey

A potential well, showing, according to classical mechanics, the minimum energy V(x) needed to reach each position x. Classically, a particle with energy E is constrained to a range of positions between x1 and x2.

Ernest Rutherford at McGill University in 1905

3D views of some hydrogen-like atomic orbitals showing probability density and phase (g orbitals and higher are not shown)

Top: Expected results: alpha particles passing through the plum pudding model of the atom undisturbed.
Bottom: Observed results: a small portion of the particles were deflected, indicating a small, concentrated charge. Diagram is not to scale; in reality the nucleus is vastly smaller than the electron shell.

This diagram shows the half-life (T½) of various isotopes with Z protons and N neutrons.

A plaque commemorating Rutherford's presence at the University of Manchester

These electron's energy levels (not to scale) are sufficient for ground states of atoms up to cadmium (5s2 4d10) inclusively. Do not forget that even the top of the diagram is lower than an unbound electron state.

An example of absorption lines in a spectrum

A statue of a young Ernest Rutherford at his memorial in Brightwater, New Zealand.

Graphic illustrating the formation of a Bose–Einstein condensate

A Russian postage depicting Scattering diagram

Scanning tunneling microscope image showing the individual atoms making up this gold (100) surface. The surface atoms deviate from the bulk crystal structure and arrange in columns several atoms wide with pits between them (See surface reconstruction).

Radioaktive Substanzen und ihre Strahlungen, 1913

Periodic table showing the origin of each element. Elements from carbon up to sulfur may be made in small stars by the alpha process. Elements beyond iron are made in large stars with slow neutron capture (s-process). Elements heavier than iron may be made in neutron star mergers or supernovae after the r-process.

The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment.

- Atomic nucleus

One or more protons are present in the nucleus of every atom.

- Proton

Every atom is composed of a nucleus and one or more electrons bound to the nucleus.

- Atom

The nucleus is made of one or more protons and a number of neutrons.

- Atom

The word proton is Greek for "first", and this name was given to the hydrogen nucleus by Ernest Rutherford in 1920.

- Proton

In 1911, although he could not prove that it was positive or negative, he theorized that atoms have their charge concentrated in a very small nucleus, and thereby pioneered the Rutherford model of the atom, through his discovery and interpretation of Rutherford scattering by the gold foil experiment of Hans Geiger and Ernest Marsden.

- Ernest Rutherford

As a result, he discovered the emission of a subatomic particle which, in 1919, he called the "hydrogen atom" but, in 1920, he more accurately named the proton.

- Ernest Rutherford

Ernest Rutherford and his colleagues Hans Geiger and Ernest Marsden came to have doubts about the Thomson model after they encountered difficulties when they tried to build an instrument to measure the charge-to-mass ratio of alpha particles (these are positively-charged particles emitted by certain radioactive substances such as radium).

- Atom

3 related topics with Alpha

Electron

2 links

Subatomic particle whose electric charge is negative one elementary charge.

A beam of electrons deflected in a circle by a magnetic field

The Bohr model of the atom, showing states of an electron with energy quantized by the number n. An electron dropping to a lower orbit emits a photon equal to the energy difference between the orbits.

In quantum mechanics, the behavior of an electron in an atom is described by an orbital, which is a probability distribution rather than an orbit. In the figure, the shading indicates the relative probability to "find" the electron, having the energy corresponding to the given quantum numbers, at that point.

Standard Model of elementary particles. The electron (symbol e) is on the left.

Example of an antisymmetric wave function for a quantum state of two identical fermions in a 1-dimensional box. If the particles swap position, the wave function inverts its sign.

A schematic depiction of virtual electron–positron pairs appearing at random near an electron (at lower left)

A particle with charge q (at left) is moving with velocity v through a magnetic field B that is oriented toward the viewer. For an electron, q is negative so it follows a curved trajectory toward the top.

Here, Bremsstrahlung is produced by an electron e deflected by the electric field of an atomic nucleus. The energy change E2 − E1 determines the frequency f of the emitted photon.

Probability densities for the first few hydrogen atom orbitals, seen in cross-section. The energy level of a bound electron determines the orbital it occupies, and the color reflects the probability of finding the electron at a given position.

A lightning discharge consists primarily of a flow of electrons. The electric potential needed for lightning can be generated by a triboelectric effect.

Lorentz factor as a function of velocity. It starts at value 1 and goes to infinity as v approaches c.

Pair production of an electron and positron, caused by the close approach of a photon with an atomic nucleus. The lightning symbol represents an exchange of a virtual photon, thus an electric force acts. The angle between the particles is very small.

An extended air shower generated by an energetic cosmic ray striking the Earth's atmosphere

Aurorae are mostly caused by energetic electrons precipitating into the atmosphere.

During a NASA wind tunnel test, a model of the Space Shuttle is targeted by a beam of electrons, simulating the effect of ionizing gases during re-entry.

The electron's mass is approximately 1836 times smaller than that of the proton.

The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms.

These radioactive materials became the subject of much interest by scientists, including the New Zealand physicist Ernest Rutherford who discovered they emitted particles.

Neutron

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Nuclear fission caused by absorption of a neutron by uranium-235. The heavy nuclide fragments into lighter components and additional neutrons.

Models depicting the nucleus and electron energy levels in hydrogen, helium, lithium, and neon atoms. In reality, the diameter of the nucleus is about 100,000 times smaller than the diameter of the atom.

A schematic of the nucleus of an atom indicating radiation, the emission of a fast electron from the nucleus (the accompanying antineutrino is omitted). In the Rutherford model for the nucleus, red spheres were protons with positive charge and blue spheres were protons tightly bound to an electron with no net charge.
The inset shows beta decay of a free neutron as it is understood today; an electron and antineutrino are created in this process.

The Feynman diagram for beta decay of a neutron into a proton, electron, and electron antineutrino via an intermediate heavy W boson

The leading-order Feynman diagram for decay of a proton into a neutron, positron, and electron neutrino via an intermediate boson.

Institut Laue–Langevin (ILL) in Grenoble, France – a major neutron research facility.

Cold neutron source providing neutrons at about the temperature of liquid hydrogen

The fusion reaction rate increases rapidly with temperature until it maximizes and then gradually drops off. The D–T rate peaks at a lower temperature (about 70 keV, or 800 million kelvins) and at a higher value than other reactions commonly considered for fusion energy.

Transmutation flow in light water reactor, which is a thermal-spectrum reactor

The neutron is a subatomic particle, symbol or, which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton.

Protons and neutrons constitute the nuclei of atoms.

In 1920, Ernest Rutherford suggested that the nucleus consisted of positive protons and neutrally charged particles, suggested to be a proton and an electron bound in some way.

Alpha particle

2 links

Alpha radiation detected in an isopropanol cloud chamber (after injection of an artificial source radon-220).

Example selection of radioactive nuclides with main emitted alpha particle energies plotted against their atomic number. Note that each nuclide has a distinct alpha spectrum.

Alpha radiation consists of helium-4 nucleus and is readily stopped by a sheet of paper. Beta radiation, consisting of electrons, is halted by an aluminium plate. Gamma radiation is eventually absorbed as it penetrates a dense material. Lead is good at absorbing gamma radiation, due to its density.

An alpha particle is deflected by a magnetic field

Dispersing of alpha particles on a thin metal sheet

Energy-loss (Bragg curve) in air for typical alpha particle emitted through radioactive decay.

The trace of a single alpha particle obtained by nuclear physicist Wolfhart Willimczik with his spark chamber specially made for alpha particles.

Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus.

When an atom emits an alpha particle in alpha decay, the atom's mass number decreases by four due to the loss of the four nucleons in the alpha particle.

In 1899, physicists Ernest Rutherford (working in McGill University in Montreal, Canada) and Paul Villard (working in Paris) separated radiation into three types: eventually named alpha, beta, and gamma by Rutherford, based on penetration of objects and deflection by a magnetic field.