Learning Guides 7 and 8 Flashcards
The positively charged central mass of an atom where electrons orbit; composed of the nucleons (protons and neutrons)
Nucleus
The ones accounted for the mass of an atom
Nucleons
Each of two or more forms of a chemical element with the same atomic number but different numbers of neutrons
Isotopes
The spontaneous disintegration of the atomic nuclei by subsequent emission of subatomic particles
Radioactivity
Particles in radioactivity
Alpha, beta, electromagnetic rays
Discovered the phenomenon of radioactivity
Antoine Henri Becquerel in 1896
An element that was observed that can blacken a photographic plate
Uranium
A device used to measure the amount of electric charge of an object
Electroscope
Inferred that radioactivity is associated with atoms; carried out experiments using polonium and radium (radioactive elements)
Pierre and Marie Curie
Referred to decay-period
Half-life
Kind of decay that emits a helium atom (alpha particle)
Alpha decay
Involves a conversion of neutron to proton; releases electron (beta particle)
Beta decay
Termed as “relaxation” because it’s only a release of energy that simultaneously accompanies alpha and beta decay.
Gamma emission
These radioactive decays are subtypes of the beta decay.
Positron emission and electron capture
Wherein a proton changes into a neutron and an excess positive charge is emitted
Positron emission
The so called capture of the electron allows a proton to turn into a neutron
Electron capture
Where stability of atoms depend on
Number of neutrons and protons (N, Z)
The pattern of black lines; combinations of neutrons and protons that yield stable nuclei
Belt of stability
The splitting of a nucleus that releases energy
Nuclear fission (“breaking up”)
The combination of atoms that release energy
Nuclear fusion
Devices used to accelerate charged particles at high energies
Particle accelerators
Three parts of particle accelerators:
A source of the particle, tube pumped to a partial vacuum, a mean to speed up the particle
A theory that proposes to combine the four known fundamental forces of nature
Unified Field Theory
Four fundamental forces of nature:
Strong nuclear force, electromagnetic force, weak nuclear force, gravitational force
Defined as a round object in space that orbits a star
Planet
Qualifications of a planet:
Orbits a star, large enough to assume hydrostatic equilibrium (nearly round shape), has “cleared the neighborhood” around its orbit
Mass of gasses in space that generate energy through thermonuclear reactions
Star
An assembly of stars, planets, gas, and dust that forms a unit within the universe
Galaxy
The totality of all masses and energy that exists in the immense space
Universe
Cosmic bodies with high energy output
Quasars
Identified galaxies beyond our own; used telescopes to estimate distances in extragalactic realm
Edwin Hubble
The greater distance to a galaxy, the more its color shifted towards red; a change in a star’s spectrum towards longer wavelengths
Redshift
States that the redshifts in the spectra of distant galaxies are proportional to their distance
Hubble’s Law
Studied stellar structure, stellar dynamics, white dwarfs; Investigation of The Mathematical Theory of Black Holes
Subrahmanyan Chandrasekhar (“Chandra”)
Massive objects that have been completely and violently crunched by extreme gravitational collapse
Black Holes
British theoretical physicist with groundbreaking works on black hole and relativity; “A Brief History of Time”
Stephen Hawkings
Referred to when a star does not have sufficient mass to explode in a supernova
“Dead star” or white dwarf
Producing neutron stars
Supernova
Inert stellar cores that remain after a star has ended all core nuclear fusion
White dwarfs
Stars composed of neutrons; created by the collapse of an iron core in a massive supernova approximately 10 miles in diameter
Neutron stars
A location in space where gravity is so strong that neither particles nor light can escape from it
Black holes
An intrinsic expansion where the scale of space itself changes
The Expanding Universe Theory
One of the “future scenes” that scientists proposed will be the fate of the universe; tells that eventually after much expansion, the universe will eventually collapse
Big Crunch
