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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.
Hydrogen was known to be the lightest element, and its nuclei presumably the lightest nuclei. Now, because of all these considerations, Rutherford decided that a hydrogen nucleus was possibly a fundamental building block of all nuclei, and also possibly a new fundamental particle as well, since nothing was known to be lighter than that nucleus.
A schematic of the nucleus of an atom indicating β − radiation, the emission of a fast electron from the nucleus (the accompanying antineutrino is omitted). In the Rutherford model for the nucleus, a red sphere was a proton with positive charge, and a blue sphere was a proton tightly bound to an electron, with no net charge.
The nucleus was the first organelle to be discovered. What is most likely the oldest preserved drawing dates back to the early microscopist Antonie van Leeuwenhoek (1632–1723). He observed a "lumen", the nucleus, in the red blood cells of salmon . [ 97 ]
Scientists eventually discovered that atoms have a positively charged nucleus (with an atomic number of charges) in the center, with a radius of about 1.2 × 10 −15 meters × [atomic mass number] 1 ⁄ 3. Electrons were found to be even smaller.
After the neutron was discovered, scientists realized the helium nucleus in fact contained two protons and two neutrons. Discovery of the neutron Physicists in the 1920s believed that the atomic nucleus contained protons plus a number of "nuclear electrons" that reduced the overall charge.
The reason is that every time you add a neutron, you’re creating a new nucleus that is going to decay. So, you must add the neutrons fast enough to get all eight neutrons into the target nuclei ...
Robert Brown was born in Montrose, Scotland on 21 December 1773, in a house that existed on the site where Montrose Library currently stands. He was the son of James Brown, a minister in the Scottish Episcopal Church with Jacobite convictions so strong that in 1788 he defied his church's decision to give allegiance to George III.