atomic theory Flashcards
Who was john dalton known as? What did he do?
The father of the atomic theory?
He was the first to develop an atomic theory based on scientific observation
What did dalton believe about atoms? (4)
- all matter is made of atoms
- atoms can’t be broken down further
- atoms within one element are the same, and atoms within other elements are not
- atoms are rearranged, not lost (law of conservation of mass)
What is the law of multiple proportions?
when two elements combine with each other to form more than one compound, the masses of one element that combine with a fixed mass of the other are in a ratio of small whole numbers.
ex: in CO2, the ratio of carbon to oxygen is 1:2
Atoms and molecules are the smallest particles a substance can be and still retain it’s _______
chemical and physical properties
Who was jj thompson?
The man who discovered the electron and created the plum pudding model of the atom
How did thompson discover electrons?
He built a cathode ray tube using electromagnetic radiation theory to prove that there were negatively charged particles in atoms
What is a cathode ray tube? (like the one thompson used)
a close glass cylinder where most air has been removed, and there are two electrodes, places where electron transfer occurs; a cathode (negative), and an anode (positive)
What is the ratio of electric charge to the mass of a single electron?
-1.76 * 10^8 Coulomb/g
What is the plum pudding model?
A model where all the electrons and protons are just plopped in the atom, sitting around. The negative charges canceled out the positive charges.
Who was Ernest rutherford?
The man who discovered the nucleus
How did rutherford discover the nucleus? What did he notice during his experiment?
He shot alpha particles (made of two neutrons and two protons) through a gold foil, and noticed that some went straight through but others bounced back
What did rutherford theorize after the gold foil experiment?(2)
atoms are mostly made of empty space
atoms have a positively charged center
Who was RA Millikan?
determined the size of the charge of an electron and the mass of an electron
What experiment did Millikan perform?
The oil drop experiment, where a negative charge was put on a drop of oil and then Millikan determined how much electric charge has to be applied to suspend the oil drop in an electronic field between two metal plates
Who was James Chadwick?
The man who discovered the neutron
