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Smallest particle of an element that retains its identity in a chemical reaction
atom
Negatively charged subatomic particle
electron
Positively charged subatomic particle
proton
Neutral atoms have the same number of
protons and electrons
Type of radiation that doesn't change mass or atomic number
gamma
First person documented as believing in the existence of atoms
Democritus
Discovered the electron
J.J. Thomson
Discovered the proton
H. Moseley
Determines the identity of the atom
mass number and atomic number of element with 6 protons, 6 electrons, and 7 neutrons
mass number = 13
atomic number = 6
Theory that transformed Democritus' ideas about the atom.
Dalton's Atomic Theory
Instrument used to discover the electron
cathode ray tube
Number of protons is the same as
atomic number
Elements with the same number of protons, but different number of neutrons
isotopes
unstable nuclei undergo ____________ to become stable
radioactive decay
Avogadro's number
6.02 x 1023
Location of the negatively charged subatomic particle
electron cloud
Discovered the neutron
Chadwick
Protons plus neutron
mass number
Type of decay that doesn't change the mass, but changes the atomic number
beta
Law that states matter cannot be created or destroyed
Law of conservation of mass
Unit of measure that allow us to weigh and count arms and other very tiny particles
Chemical mole
Proposed the plum pudding model of the atom
J.J. Thomson
Highest penetrating ability of all types of radiation
gamma
Particle emitted during beta decay
electron