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A picture of a neutron. The 'u' stands for an up quark, and the 'd' stands for a down quark.

Neutrons, with protons and electrons, make up an atom. Neutrons and protons are found in the nucleus of an atom.[1][2][3] Unlike protons, which have a positive charge, or electrons, which have a negative charge, neutrons have zero charge.[1][4] Neutrons bind with protons with the residual strong force.

Neutrons were predicted by Ernest Rutherford,[5] and discovered by James Chadwick,[6][7] in 1932.[6] Atoms were fired at a thin pane of beryllium. Particles emerged which had no charge, and he called these 'neutrons'.

Neutrons have a mass of 1.675 × 10-24g,[8] which is a little heavier than the proton.[8] Neutrons are 1839 times heavier than electrons.[8]

Like all hadrons, neutrons are made of quarks. A neutron is made of two down quarks and one up quark.[2][3] One up quark has a charge of +2/3, and the two down quarks each have a charge of -1/3. The fact that these charges cancel out is why neutrons have a neutral (0) charge. Quarks are held together by gluons.

Isotopes[change | edit source]

Neutrons can be found in almost all atoms alongside protons and electrons, hydrogen-1 being the single common exception. The number of them in the atom does not change the element, unlike protons. However, it does change some characteristics of the element or ore. The number of them in an atom determines what isotope this compound is.

Atomic reactions[change | edit source]

Neutrons are the key to nuclear chain reactions, nuclear power and nuclear weapons.

References[change | edit source]

  1. 1.0 1.1 Woolley, Steve (2011). Edexcel IGCSE Physics Revision Guide. Pearson Education. p. 20-21. ISBN 9780435046736.
  2. 2.0 2.1 Cox, Brian; Cohen, Andrew (2011). Wonders of the Universe. HarperCollins. p. 79, 108. ISBN 9780007395828.
  3. 3.0 3.1 Nave, R. (2007-01-15). "Protons and neutrons". Retrieved 2011-07-15.
  4. Ryan, Lawrie (2001). Chemistry for you: revised National Curriculum edition for GCSE (Second ed.). Nelson Thornes. p. 29. ISBN 9780748762347.
  6. 6.0 6.1 "Discovery of Neutrons". Helmholtz Zentrum Berlin. 2008-08-23. Retrieved 2011-04-14.
  7. "The Nobel Prize in Physics 1935: James Chadwick". Retrieved 2011-04-15.
  8. 8.0 8.1 8.2 "Neutron (subatomic particle)". Encyclopædia Britannica Online. Encyclopædia Britannica. Retrieved on 14 April 2011. 

Other pages[change | edit source]