Rutherford scattering is a phenomenon that was explained by Ernest Rutherford in 1911, and led to the development of the orbital theory of the atom. It is now exploited by the materials analytical technique Rutherford backscattering. Rutherford scattering is also sometimes referred to as Coulomb scattering because it relies on static electric (Coulomb) forces. A similar process probed the insides of nuclei in the 1960s, called Deep Inelastic Scattering. Ernest Rutherford, 1st Baron Rutherford of Nelson, OM, FRS (August 30, 1871 - October 19, 1937), called father of nuclear physics, pioneered the orbital theory of the atom notably in his discovery of rutherford scattering off the nucleus with his gold foil experiment. ... Jump to: navigation, search 1911 was a common year starting on Sunday (click on link for calendar). ... Properties For alternative meanings see atom (disambiguation). ... Rutherford backscattering (or RBS, for Rutherford Backscattering Spectrometry) is an analytical technique in materials science. ... Static electricity is a class of phenomena involving the net charge present on an object; typically referring to charged object with voltages of sufficient magnitude to produce visible attraction, repulsion, and sparks. ... The coulomb (symbol: C) is the SI unit of electric charge. ... In physics, a force is an external cause responsible for any change of a physical system. ... Deep Inelastic Scattering is the name given to a process used to probe the insides of hadrons (particularly the baryons, such as protons and neutrons), using electrons. ...

The discovery was made by Hans Geiger and Ernest Marsden in 1909 when they performed the Gold foil experiment under the direction of Rutherford, in which they fired a beam of alpha particles (helium nuclei) at layers of gold leaf only a few atoms thick. At the time of the experiment, the atom was thought to be analogous to a plum pudding (as proposed by J.J. Thomson), with the negative charges (the plums) found throughout a positive sphere (the pudding). If the plum-pudding model were correct, the positive “pudding”, being more spread out than in the current model of a concentrated nucleus, would not be able to exert such large coulombic forces, and the alpha particles should only be deflected by small angles as they pass through. Johannes ( Hans ) Wilhelm Geiger (September 30, 1882 – September 24, 1945) was a German physicist. ... Sir Ernest Marsden (1888 - 1970), was a British-New Zealand physicist. ... 1909 was a common year starting on Friday (see link for calendar). ... Top: Expected results: alpha particles passing through the plum pudding model of the atom undisturbed. ... An alpha particle is deflected by a magnetic field Alpha particles or alpha rays (named after the first letter in the greek alphabet) are a form of particle radiation which are highly ionizing and have low penetration. ... Jump to: navigation, search General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... General Name, Symbol, Number gold, Au, 79 Chemical series transition metals Group, Period, Block 11, 6, d Appearance metallic yellow Atomic mass 196. ... Sir Joseph John Thomson, OM , FRS (December 18, 1856 – August 30, 1940) often known as J. J. Thomson, was an English physicist, the discoverer of the electron. ... Plural: nuclei In chemistry and physics, the nucleus (atomic nucleus) is the collection of protons and neutrons in the center of an atom that carries the bulk of the atoms mass and positive charge. ...

However, the intriguing results showed that around 1 in 8000 alpha particles were deflected by very large angles (over 90°). From this, Rutherford concluded that the majority of the mass was concentrated in a minute, positively charged region (the nucleus) surrounded by electrons. When a (positive) alpha particle approached sufficiently close to the nucleus, it was repelled strongly enough to rebound at high angles. The small size of the nucleus explained the small number of alpha particles that were repelled in this way. Rutherford showed, using the method below, that the size of the nucleus was about 10⁻¹⁴ m. Mass is a property of physical objects that, roughly speaking, measures the amount of matter they contain. ...

Details of calculating nuclear size

For head on collisions between alpha particles and the nucleus, all the kinetic energy () of the alpha particle is turned into potential energy and the particle is at rest. The distance from the centre of the alpha particle to the centre of the nucleus (b) at this point is a maximum value for the radius, if it is evident from the experiment that the particles have not hit the nucleus. Jump to: navigation, search Kinetic energy is energy that a body has as a result of its speed. ... Potential energy is stored energy. ...

Applying the inverse-square law between the charges on the electron and nucleus, one can write: This diagram shows how the law works. ...

Rearranging:

For an alpha particle:

• m (mass) = 6.7×10⁻²⁷ kg
• q₁ = 2×(1.6×10⁻¹⁹) C
• q₂ (for gold) = 79×(1.6×10⁻¹⁹) C
• v (initial velocity) = 2×10⁷ m/s

Substituting these in gives the value of about 2.7×10⁻¹⁴ m. (The true radius is about 5.6×10⁻¹⁵ m.)

See also:

Coulomb collision A Coulomb collision is a collision between two particles when the force between them is given by Coulombs Law. ...

References

• The Scattering of α and β Particles by Matter and the Structure of the Atom, E. Rutherford, Philosophical Magazine. Series 6, vol. 21. May 1911
• On a Diffuse Reflection of the α-Particles, H. Geiger and E. Marsden, Proceedings of the Royal Society, 1909 A vol. 82, p. 495-500