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History of atomic theory. The current theoretical model of the atom involves a dense nucleus surrounded by a probabilistic "cloud" of electrons. Atomic theory is the scientific theory that matter is composed of particles called atoms. The definition of the word "atom" has changed over the years in response to scientific discoveries.
Electrons and a compact nucleus of protons and neutrons. Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms.
Rutherford's first steps towards the his discovery of the nature of the atom came from his work to understand alpha particles. [21]: 17 [34]: 435 In 1906, Rutherford noticed that alpha particles passing through sheets of mica were deflected by the sheets by as much as 2 degrees. Rutherford placed a radioactive source in a sealed tube ending ...
The history of the periodic table is also a history of the discovery of the chemical elements. The first person in recorded history to discover a new element was Hennig Brand, a bankrupt German merchant. Brand tried to discover the philosopher's stone —a mythical object that was supposed to turn inexpensive base metals into gold.
J. Robert Oppenheimer. J. Robert Oppenheimer (born Julius Robert Oppenheimer; / ˈɒpənhaɪmər / OP-ən-hy-mər; April 22, 1904 – February 18, 1967) was an American theoretical physicist who served as the director of the Manhattan Project 's Los Alamos Laboratory during World War II. He is often called the "father of the atomic bomb " for ...
Ernest Rutherford. Ernest Rutherford, 1st Baron Rutherford of Nelson, OM, FRS, HonFRSE [7] (30 August 1871 – 19 October 1937), was a New Zealand physicist who was a pioneering researcher in both atomic and nuclear physics. He has been described as "the father of nuclear physics", [8] and "the greatest experimentalist since Michael Faraday ". [9]
The discoveries of the 118 chemical elements known to exist as of 2024 are presented here in chronological order. The elements are listed generally in the order in which each was first defined as the pure element, as the exact date of discovery of most elements cannot be accurately determined. There are plans to synthesize more elements, and it ...
Otto Hahn (pronounced [ˈɔtoː ˈhaːn] ⓘ; 8 March 1879 – 28 July 1968) was a German chemist who was a pioneer in the fields of radioactivity and radiochemistry. He is referred to as the father of nuclear chemistry and father of nuclear fission. Hahn and Lise Meitner discovered radioactive isotopes of radium, thorium, protactinium and uranium.