Question

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19. Where do particles come from?
20. What are the energy levels of an atom?
21. What is Quantum Mechanic?

Answer 1

19. Particles come from the bonding of 2 or more elementary particles (like quarks). The bond between these particles is maintained by the strong nuclear force. For example, a proton is is made with 2 up quarks and a down quark.
20. The energy levels of an atom correspond the orbitals of electrons that surround that atom. These orbitals are discrete and quantized, meaning that they can only occur at specific energies (as opposed to being able to orbit at any arbitrary energy on a continuum of energy levels) and are always multiples of Plank's constant, h = 6.626*10^{-34} m^2*kg/s.
21. In one sentence, Quantum Mechanics is a mathematical model of the physical universe that posits the nature of the universe is quantized, meaning that properties like energy and angular momentum only come in multiples of a fundamental constant known as Plank's constant. This has far reaching implications, such as particle-wave duality for matter and light and the idea that there is indeed a FUNDAMENTAL limit to the precision with which certain pairs of physical properties can be known.

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