2.1.1 atomic structure and isotopes

isotopes

atoms of the same element with differnt numbers of neutrons and different masses

atoms are small, industructible

dalton's model

experiments shows that the atom must contain smaller, negatively charged particles
positiverly charged sphere with smaller, negatively charged particle

plum pudding model

fired particles at a gold sheet which showes that most of the atom has a positive charge and dense centre with electrons orbit it

geriger-marsden experiment

the atoms was heavier if it only have protons

james chadwick

electrons orbit the nucleus in fixed shells

bohr's model

relative isotopic mass

The mass of an isotope compared with one twelfth of the mass of an atom of carbon-12

relative atomic mass

The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12.

mass spectrometer

an instrument used to find the percentage abundance of the isotopes in a sample of an element

relative atomic mass

(isotope mass x isotope abundance)/total abundance

moles

mass/Mr