PHYSICS: MODERN PHYSICS Flashcards
Structure of the atom
-has a nucleus of positively charged protons and uncharged neutrons
-the nucleus is surrounded by negatively charged electrons
-the mass of a nucleus is lighter than all the protons and neutrons that make it up
-this mass difference is known as the mass defect
-the mass defect represents the energy in the bonds holding the nucleus together
Radioactivity
-an atoms nucleus could spontaneously disintegrate while giving off energy in the form of alpha and beta particles and gamma rays
-this phenomenon is known as radioactivity
-this spontaneous change in the nucleus of an atom is known as radioactive decay
Transmutation
Conversion of one element into another element
Nuclear reaction
-when a radioactive nucleus goes through a transmutation there are two main processes of nuclear reactions:
-fusion: the nuclei of several light atoms combine to form a single heavy nucleus with a release of energy
-fission: a heavy nucleus splits into two main pieces with the release of a huge amount of energy
Quantum mechanics
-theory that explains the behavior of light
-asserts that the behavior of light is a combination of particles and waves
-an example that illustrates this wave-particle duality is the photoelectric effect
-when a light wave strikes certain metallic surfaces, electrons are emitted
-this effect, called ionization, means that an atom loses an electron (or several electrons) and becomes an ion
Albert Einstein’s theory of relativity
-devised in 1905
-one of the greatest accomplishments of modern physics
-the identification of the existence of an upper limit on velocity
-this upper limit (c, also known as the speed of light through a vacuum) is the fastest that any particle can travel
-according to the theory, the speed of light is absolute, and material particles can never reach the speed of light
-upper limit (c) also known as speed of light through a vacuum
