Atoms Flashcards
how was the alpha-scattering experiment carried out?
scientists fired tiny alpha particles at some gold foil
what did they notice during the alpha- scattering experiment?
what did this tell them?
- some particles went straight through the gold foil
atoms are mainly empty space
- some deflected (changed direction) as it passed through the gold foil
centre of the atom must have a positive charge because the positive alpha particles repelled
- some bounced back
centre of the atom must contain a great deal of mass
what did the plum pudding model say an atom was?
a ball of positive charge with negative electrons within it
what did the nuclear model say an atom was? (3)
- most of it was empty space
- it had a positive nucleus in the centre which contained most of the mass of the atom
- around the edge are negative electrons
who created the plum pudding model?
jj thomson
who created the nuclear model?
ernest rutherford
what did neils bohr discover?
‘electrons orbit the nucleus at specific/ different distances’
what did james chadwick discover?
nucleus contains neutral particles
what is the radius of an atom?
what is the radius of a nucleus?
1 x 10 -10
1 x 10 -14
what is atomic mass?
the top number (protons and neutrons added together)
what is atomic number?
bottom number (protons and therefore electrons)
define isotope
atoms of the same element but with a different number of neutron
define ion
an atom that has an overall charge because it has lost or gained electrons
how to calculate relative atomic mass?
(mass of isotope 1 x percentage abundance of isotope 1) + (mass of isotope 2 x percentage abundance of isotope 2)
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100
what did john newlands do?
arranged the elements in order of increasing atomic mass
