4.1 atoms and isotopes

the approximate radius of an atom is

1 x 10^-10 metres

what are the three subatomic particles

protons,neutrons,electrons

where is most of the mass of an atom concentrated

in the nucleus

approx what proportion of the radius of the atom is the nucleus

1/10,000

ways an atoms electron arrangement can be changed

absorbing or emitting electromagnetic radiation

when an atom has absorbed EM radiation, electrons

move further away from the nucleus to a higher energy level

when an atom emits EM radiation, electrons

move closer to the nucleus, they move to a lower energy level

name given to number of protons in an atom

atomic number

what’s an isotope of an atom

an atom of an element that has the same number of protons but a different number of neutrons

what may lead to a scientific model being changed

discovery of new experimental evidence which doesn’t agree with existing theory

in the plum pudding model, the atom

was a sphere of positive embedded with negative electrons throughout

prior to the discovery of electrons, the atom was believed to be

indivisable

the …………………… lead to the plum pudding model being discarded

gold foil/alpha-scattering by rutherford

our current accepted model of the atom is

the Bohr nuclear model

the gold foil experiment concluded thati

most of the mass of the atom is concentrated at the centre in the nucleus, nucleus is positively charged

what reinforces a scientific theory

when experimental results agree with the hypothesised theoretical calculations and theories

James Chadwick’s experiments on the atom proved

the existence of neutrons

if an experiment is reproducible it

has been repeated by a different scientist and got the same results