History Of Atoms Flashcards
What idea about the atom did John Dalton come up with?
Substances were made up of atoms that were like tiny, hard spheres. He also suggested that each chemical element had its own atoms that differed from others in their mass. Dalton believed that these atoms could not be divided or split. He suggested that in chemical reactions the atoms re-arranged themselves and combined with other atoms in new ways.
What idea about the atom did J.J. Thomson come up with?
The negatively charged electrons must be embedded in a cloud of positive charge. He knew that the atoms themselves carry no overall charge, so any charges in an atom must balance out. He imagined the electrons as the bits of plum in a plum pudding.
What was the model of the atom J.J. Thomson come up with?
The plum pudding model.
What was Rutherford’s idea about the atom?
The positive charge must be concentrated at a tiny spot in the centre of the atom otherwise the large, positive particles fired at the foil could never be repelled back towards their source. The electrons must be orbiting around this nucleus (centre of the atom), which contains very dense positively charged protons.
What model did Rutherford come up with?
The nuclear model.
What idea about the atom did Bohr come up with?
The electrons must be orbiting the nucleus at set distances, in certain fixed energy levels (or shells). The energy must be given out when excited electrons fall out from a high to a low energy level.
Which scientist gave evidence for neutrons in the nucleus?
James Chadwick in 1932.
