development of the model of the atom. Flashcards
what were atoms originally thought to be?
tiny spheres that could not be divided.
who discovered the electron and when?
J. J. Thompson in 1897.
what did J. J. Thompson’s discovery of the electron lead to?
plum pudding model of the atom.
what is the plum pudding model?
(describe what it look like and contains.)
depicts the atom as a ball of positive charge with electrons embedded in it ( like plums in a pudding.)
balance the charge of the electrons.
mass and charge uniformly distributed.
what did Rutherford and Marsden do in 1905 that lead to the finding an knowledge of the presence of the nucleus?
bombarded/ fired thing gold foil with alpha particles.
just because some particles got deflected away how did they work out there was a nucleus in the middle?
if the plum pudding model had been correct the heavy positively charged alpha particles would have been able to pass straight through which most particles did but not all.
must have come close to a concentration of charge .
what did it mean by the alpha particles being reflected back?
must have been repelled by the same charge that the alpha particles carried.
repelling charge must have been much heavier than the alpha particle or it would have passed through.
what was Rutherford and Marsden’s conclusion on the findings of their experiment?
mass of an atom was concentrated in a central nucleus, which was positively charged.
the electrons surround this nucleus.
how did Niels Bohr adapt this model?
suggested that electrons orbit the nucleus at specific distances.
what did later experiments after Niels Bohr lead to?
idea that the positive charge of the nucleus can be divided into a whole number of smaller, each with the same amount of positive charge.
what did the later experiments after Neil Bohr that showed the idea that : the positive charge of the nucleus can be divided into a whole number of smaller, each with the same amount of positive charge: be called?
proton.
in 1932 James Chadwick carried out experiments that provided evidence for what?
there was another sub-atomic particle in the nucleus called the neutron.
when describing the movement of electrons what shouldn’t you say and what should you say instead?
reflect.
rebound or recoil.
what is peer review?
scientific claims from new research that is published in journals must be peer reviewed that is evaluated by other scientists who are experts in that area of science.
when another scientist is peer reviewing someone’s work what are they looking for?
valid: was the experiment done correctly?
original: is the work new?
significant: are the results important?
