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37 Cards in this Set

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J. J Thomson

studied the properties of cathode rays

Wilhelm Roentgen

discovered x-rays

Henri Becquerel

dsicovered natural radioactivity in Uranium

Ernest Rutherford

discovered alpha, beta, and gamma radiation

Enrico Fermi

produced the first controlled fission reaction

Albert Einstein

developed the special theory of reletivity

Max Planck

developed the quantum theory of matter and energy

Arthur Compton

showed that cosmic rays are charged particles

J. Robert Oppenheimer

directed project to build first atomic bomb

cathode rays

streams of high- speed electrons emitted from a high-voltage discharge tube

x-rays

electromagnetic waves released when electrons strike a metal target

radioactive elements emit

1. high speed particles


2. energetic electromagnetic waves

alpha particle

high-speed helium nucleus emitted from the nucleus of a radioactive element

beta particle

high- speed electron emitted from the nucleus of a radioactive element

gamma ray

high- speed electromagnetic wave emitted from the nucleus of a radioactive element

cosmic rays

high- speed charged particles that strike earths atmosphere from outer space

3 kinds of spectra discovered by Gustav Kirchoff and Robert Bunsen

1. continuos


2. emission


3. absorption

photoelectric effect

the emission of electrons caused by light falling upon the surface of certain metals

photon

discrete bundle of light energy

which properties of light determine the number of photons and their energy levels

brightness


frequency

quantum

discrete bundle of energy

3 ideas and discoveries made in physics between 1895 and 1905

1. electrons


2. x-rays


3. radioactive elements

difference between modern physics and classical physics

modern takes the quantum theory into account


classical does not use the quantum theory

what determines physical properties?

the number of protons and nuetrons in an atom

physical properties are determined by

the number of protons and nuetrons in an atom

chemical properties are determined by

the number of electrons in each atom and their placement in orbitals

atomic number of an atom is determined by

the number of protons in its nucleus

atomic number

identifies elements exactly

isotopes

atoms with the same number of protons but different number of nuetrons

radioactivity

the emission of particles or rays from the nucleus of an atom


radioactivity decay can make what three kinds of fundamental changes in atoms?

1. in atomic mass


2. in atomic number


3. in energy content

half-life

the amount of time required for half of a given sample of a radioactive element to undergo radioactive decay

fission

the splitting of a heavy nucleus into 2 nuclei of medium weight

chain reaction

any process in which the material that starts the reaction is also one of the products

fusion

a nuclear reaction in which two light weight nuclei combine to form a massive nucleus with the simultaneous release of energy

special theory of relativity concludes that

energy and mass are interchangeable

formulas