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understand the Atom
Vocabulary for Understanding the Atom
Question | Answer |
---|---|
atom | smallest particle of an element that still represents that element |
electron | particle with one negative charge |
nucleus | center of the atom where protons and neutrons are located |
proton | particle with one positive charge |
neutron | neutral particle found in the nucleus |
electron cloud | part of the atom outside the nucleus that contains the electrons |
atomic number | the number of protons in an atom of an element |
isotope | an atom of the same element that have different numbers of neutrons |
mass number | is the sum of the number of protons and neutrons in an atom's nucleus |
average atomic mass | the average mass of the element's isotopes |
radioactive | elements that spontaneously emit radiation |
nuclear decay | a process that occurs when an unstable atomic nucleus changes into another more stable nucleus by emitting radiation |
ion | an atom that is no longer neutral because it has gained or lost electrons |
Democritus | said atoms are uncuttable, they are the smallest particle of matter, they are indivisible and not destructible |
Dalton | all matter is made of atoms, atoms can not be created or destroyed, all compounds are combinations of 2 or more atoms |
JJ Thompson | discovered the electron |
Ernest Rutherford | showed most of the mass of the atom is in the nucleus and the rest is empty space |
Niels Bohr | said electrons travel in energy levels around the nucleus |
Chadwick | added the addition of neutrons to the nucleus of the atom |
quark | smaller parts of the protons and neutrons |