History of the Atom Flashcards
Leucippus
Had a theory that atoms were industructible little particles that made up everything
Democritus
Student of Leucippus & gets credit for the idea of the atom
What “science” occurred during the dark ages
Alchemy
What did we get out of Alchemy
Tansmutation: Changing one substance into another
-Elements: Hg, S, Sb were discovered
-Learned how to prepare acids
-Developed several alloys
Antoine Lavoisier
Law of Conservation of Mass
What is Law of Conservation of Mass
Mass cannot be created or destroyed in ordinary chemical reactions. Mass of reactants = mass of products
What is the Law of Definite Proportions
Compounds contain the same elements in exactly the same proportions regardless of sample size or sample source
What is the Law of Multiple Proportions
If 2 or more different compounds are made of the same elements, the ration of the mass is always a small whole # ratio
John Dalton
Proposed an Atomic theory
What was Dalton’s Atomic theory
-Everything is made of indivisible particles called atoms (F: subatomic particles like p+, e-, & n0)
-Atoms of the same element are exactly alike; they have same mass (F: Isotopes)
-Compounds form from whole-number ratios of atoms: When elements combine to form compounds, they do so in simple whole-number ratios (T)
J.J Thomson
-*Discovery of the electron using a cathode ray tube
-Developed the plum pudding model
Ernest Rutherford
-Gold-foil experiment
-Led to the *discovery of the nucleus
What is the gold-foil experiment
The experiment involved firing positively charged alpha particles at a thin sheet of gold foil and observing how the particles scattered
(Atoms are mostly empty space with a small, dense, positively charged nucleus at the center)
Niels Bohr
Proposed the planetary model (Bohr model): electrons travel around nucleus of an atom & orbits it
James Chadwick
-Realized the atomic mass of most elements was double the # of p+, which led to the *discovery of the neutron
-Worked on the Manhattan Project
