p1.1+2 the particle model Flashcards
atoms
in science what is a model?
a way of visualising or representing a scientific idea to help us understand it
why might a model be updated?
when new scientific evidence cannot be explained by the original model
facts about john Dalton in 1808
-developed one of the first models of the atom
-each atom was a small indestructible sphere
-all the atoms in an element are the same
-the atoms in one element are different to ones in another
why is Daltons model of an atom different and similar compared to the modern model?
because Daltons model did not include protons, neutrons and electrons or an outer shell.
because they are both a small sphere and all the elements in an atom are the same also atoms in one element are different to ones in another
facts about J.J. Thomson in 1897
discovered the electron
it was much smaller than the atom so in 1904 he came up with a new model, plum pudding model
an atom was a positive mass
throughout it were negative charges
why did Thomson change the model of the atom?
so it would include other parts of the model he discovered
why is Thomson’s model of the atom closer to the modern model than Daltons?
it included negative charges and a positive area
what are the differences between Thomson’s model and the modern model?
in the modern model there is no positive mass but positive charges instead
the modern model also has more of a layout instead of atoms being scattered everywhere unlike Thomson’s model
why did Thomson make the atom positive?
to cancel out negative charge of the electrons
what is the approximate size of an atom?
1x10^-10m
facts about Ernst Rutherford in 1909
he developed his model of an atom by scattering alpha particles from gold foil
each atom consists of a tiny positively charged nucleus containing the mass of the atom
most of the atom is empty space
what shows the atom is mostly empty space?
when most of the alpha particles pass through the atom
what happens to the particles?
some are deflected slightly but other particles bounce back
what are positive alpha particles being repelled by?
the positive nucleus
what do atoms have a small amount of?
a small positively charged nucleus
