Developing ideas of the atom Flashcards
What did people used to think before the idea that matter was made of up of atoms was taken seriously?
a single contrinous substance that produced four elements
earth, fire, water, air
How did the idea of the atom develop?
Dalton suggested in 1803 that elements were composed of indivisible atom, each element had a different mass number
although he thought atoms could not be broken down
How were the first sub-atomic particles discovered?
the discovery of radioactivity in 1896 showed that particles could come from inside the atom
the following year, electrons were discovered, which suggested there were more sub-atomic particles due to the electrons small mass and negative charge
What was Thompson’s theory?
he suggested that electrons were located within the positively charged atom is circular arrays, like negative plums in a pudding of positive charge
What was Rutherford’s discovery?
all the positive charge of an atom was in a tiny central nucleus
What is the relative mass of an electronic?
1 / 1800