Summary
Highlights
To understand element synthesis, it's crucial to grasp essential vocabulary and concepts about atoms and nuclear reactions. This segment uses a game show format to test knowledge on alpha particles, mass number, atomic number, and types of radioactive decay.
Professor Nucleon discusses the historical discoveries of the atom. J.J. Thomson discovered electrons in 1897. Ernest Rutherford's gold foil experiment in 1911 led to the discovery of the nucleus and the understanding that atoms are mostly empty space. Rutherford later discovered protons, and James Chadwick discovered neutrons in 1932.
Teacher Eman introduces the episode, focusing on how elements are synthesized in laboratories, building upon previous discussions about element formation in extreme environments. The episode will also cover the concept of atomic number.
The periodic table has changed significantly since Mendeleev's time. Early versions had missing elements, symbolized by placeholders like UUt and UUp. Mendeleev left gaps for undiscovered elements, and the heaviest known element then was uranium. Today, many missing elements have been discovered or synthesized in laboratories.
The video explains that an atom consists of a nucleus with protons and neutrons, orbited by electrons. The combined number of protons and neutrons is the mass number. Mendeleev initially arranged elements by atomic mass, leading to inconsistencies. Henry Moseley later proved that atomic number (number of protons) determines an element's properties, resolving these issues. This established that alchemy failed because it focused on chemical mixing rather than changing the atomic number through nuclear reactions.
Professor Barrion takes over to explain how elements were synthesized. Before WWII, the periodic table had gaps for elements 43, 61, 85, and 87, with uranium as the heaviest known element. Technetium (element 43) was the first element synthesized in the laboratory in 1937 by bombarding molybdenum with deuterons. Astatine (element 85) was discovered in 1940 by colliding alpha particles with bismuth using a cyclotron.
Edwin McMillan and Philip Abelson discovered the first transuranium element, Neptunium (element 93), which is heavier than uranium. This involved uranium-238 capturing a neutron, followed by a beta decay that converted a neutron into a proton. Plutonium (element 94) was synthesized by bombarding uranium with deuterons. Later elements (95-101) were synthesized through neutron capture and alpha particle bombardment. Elements 99 and 100 were famously found in hydrogen bomb debris. The video concludes by discussing superheavy elements, which are synthesized by bombarding heavy nuclear targets with heavy projectiles, citing tennessine (element 117) and oganesson (element 118) as examples.
Teacher Eman summarizes the episode, reiterating the learned concepts of element synthesis, nuclear processes, and atomic structure. He emphasizes the constant nature of change, offering encouragement during challenging times, and introduces the next episode, which will cover the polarity of molecules with Teacher Leia.