History of the Atom - scientists/philosophers Flashcards
what concept did Democritus come up with
Greek philosopher Democritus came up with the concept of the atom, the simplest, indivisible unit of matter.
what does “atomos” in greek mean
invisisible
did Aristotle agree with Democritus
no, thus setting back scientific thinking for 2000 years
what did Aristotle believe
Greek philosopher Aristotle believed that all matter was made up of four elements: fire, water, earth, air. he believed that various types of matter existed due to different mixtures of these elements, which had different balances of hot, cold, wet, and dry. Aristotle’s elements led alchemists to attempt to turn metal into gold
did John Dalton agree with Democritus’s beliefs?
yes, he ultimately revived Democritus’s theories of atoms and strengthened it by conducting experiments
why is alchemists’ belief that metal can be turned into gold untrue
it is not physically possible because atoms cannot be made nor destroyed, therefore gold cannot be derived from metal because it is not the same elements.
which philosopher believed that all matter was made up of four elements: fire, water, earth, air.
Aristotle
what were John Dalton’s five postulates
1 - all matter is made up of small, indivisible particles called atoms
2 - all atoms of a given element are the same, and atoms of different elements are different
3 - different atoms can combine as definite whole-number ratios to form molecules/compounds (aligned with law of definite proportions)
4 - the same combination of elements can combine in more than one ratio to form different compounds (Aligned with law of multiple proportions)
5 - in chemical reactions, atoms can not be created, destroyed, or changed (Aligned with law of conservation of mass)
which of John Dalton’s postulates have been proven false
1 - all matter is made up of small, indivisible particles called atoms
2 - all atoms of a given element are the same, and atoms of different elements are different
what experiment did English scientist JJ Thomson conduct
did research with a cathode ray tube and discovered electrons
what did these results of Rutherford’s Gold Foil Experiment show
1 - most alpha particles traveled throughout undeflected
2 - some alpha particles are deflected by small angles
3 - occasionally, an alpha particle travels back from the foil
1 - most of the space in the atom is empty (where the electrons are)
2 - there is a positive nucleus charge within the atom
3 - there is a centralized area of mass in the atoms (the nucleus was all mass and is very dense)
what happened when JJ Thomson put a magnet near the cathode ray
the rays bent
what did Thomson discover
discovered the electron first.
what did Thomson believe an atom looked like
believed that electrons were distributed randomly throughout (Plum Pudding/Chocolate Chip Cookie model) (mass and charge evenly distributed)
what experiment did English Scientist Ernest Rutherford conduct
the gold foil experiment. believed that the alpha particles would not be affected because he thought the mass and charge was evenly distributed.
