atomic structure

isotope definition

same number of protons but different number of neutrons

why do isotopes have the same chemical properties

same electron configuration

why do isotopes have different physical properties

different mass of atoms

describe how JJ Thompson model of the atom was different from Daltons model

Dalton described atoms as solid spheres whereas Thompson said they were positively charged pudding with negative electrons inside

what experiment did Rutherford do and what did this mean

Gold foil experiment. fired alpha particles at thin sheet of gold. most alpha particles passed straight through - most of the atom is empty space. some deflected backwards suggesting positive nucleus surrounded by a cloud of negative electrons

describe Bohrs model of the atom

• electrons exist in fixed orbitals

• each shell has a fixed energy level

definition of relative atomic mass

the average mass of an atom of an element on a scale where an atom of carbon -12 is exactly 12

definition of relative molecular mass

the average mass of a molecule on a scale where an aytom of carbon-12 is exactly 12

what is a mass spectrometer

a machine used to analyse elements or compounds