lesson 7 alpha scattering experiment Flashcards
1000 years ago, the ancient Greeks believed everything was made from of
atoms
ancient Greeks believed atoms are what
tiny spheres that cannot be divided
how long was the ancient Greeks idea of atoms accepted for
hundereds of years
in 1897 what did scientists discover
atoms contain tiny negative particles
in 1897 what did the scientists call the tiny negative particles
electrons
what did the discovery of electrons tell scientists
that atoms are not tiny spheres that cannot be divided
scientists believed what after concluding atoms are not tiny spheres that cannot be divided
instead the believed atoms must have an internal structure
scientists suggested a new model for the structure of atoms, called what
the plum pudding model
in the plum pudding model, the atom is what
a ball of positive charge, with negative electrons embedded in it
which experiment was carried out to figure out if the plum pudding model was correct
the alpha scattering experiment
why is the alpha scattering experiment one of the most important in science
because it radically changed the way we think about atoms
what was the first step of the alpha scattering experiment (step 1)
scientists took a piece of gold foil
why did scientists use a ‘gold’ foil for the alpha scattering experiment
-how many atoms thick
as we can hammer gold into a very thin foil
-just a few atoms thick
scientists then did what after taking a piece of gold foil (step 2)
fired tiny particles at the gold foil
what are the tiny particles called that were fired at the gold foil
alpha particles
which charge are alpha particles
positive charge
scientists found most of the alpha particles pass through the gold foil in what way
they passed through the gold foil, without changing direction
sometimes what would happen to the alpha particle as it would pass its way through the gold foil
it would deflect
(change direction)
sometimes the alpha particle would do what
bounce straight off the gold foil
the fact that most of the alpha particles went straight through the gold foil interpreted what
that atoms are mainly empty space
the fact that the scientists interpreted that atoms were mainly empty spaced made them realise what
that the plum pudding model had to be wrong
secondly because some of the alpha particles were deflected, interpreted what
that the centre of the atom must have a positive charge
alpha particles are positive, so any alpha particle that comes close to the positive centre of the atom would what
repel and change direction
Finally because some alpha particles bounced straight back interpreted what
that the centre of an atom must contain a great deal of mass
we now call the central part of the atom the what
nucleus
From the results of the alpha scattering experiment, scientists replaced the plum pudding model with what
the nuclear model
in the nuclear model, most the atom is what
simply empty space
in the centre of the atom in the nuclear model, what do we have
a tiny positive nucleus, containing most the mass of an atom
around the edge of an atom in the nuclear model, what do we have
negative electrons
new experimental evidence, led the change of a plum pudding model to a wat
nuclear model
