physics- reviison test

Models of the atom

Thomson's plum pudding model of the atom is based on the concept that an atom's structure is similar in structure to a plum pudding. IT was thought that the very small negatively chargwd electrons were embedded in the atom like raisons in plum pudding, which had an overall positive charge. it was lacking anucleus, neutrons and outer shell of electrons.

Experiment- geiger and Marsden- alpha particles would be fired at thin sheet of metal and see outcomes

diagram

The alpha particles were detected as bright tiny flashes of light on a screen of zinc sulphide.

The particles were expected to go through the foil. Most alpha particles went trhough gold undeflected, detected.

Small minority of particles bounced off at an unusual angle (deflected)

most of the alpha particles went through the sheet easily. 1 particle in a million hit a small dent which caused it to deflect at a wider angle or back where it came from. Explained how atom has nucleus containing most of mass of atom, hardlya ny alpha particles hit nucleus so nucleus must be small, surrounded by shell of light electrons

rutherford model of the atom- lots of empty space, occupied by negatively charged electrons, tiny nucleus at centre, made of neutrons and protons. nucleus-small, mass concentrated, nucleus positively charged- centre of atom.

compared to football stadium, nucleus is a pea

Rutherfor studied the structure of the nucleus and discovered the proton. Chedwick proposed existance of neutron…