Model of the Atom Flashcards
Who came first with an idea of the atom?
John Dalton
What sort of experiment did Dalton do to come to the conclusion that everything was made of atoms?
experiments to measure how elements combined
What were Daltons findings about the atom?
- All the atoms in an element are the same
- The atoms in one element are different from the atoms in all other elements
What did Dalton say the atom looked like?
a very small indestructible sphere
Who came second with an idea about the atom?
J.J. Thomson
How did JJ Thomson come to find his model of the atom?
investigating rays given out by hot metals
What exactly did Thomson discover through his experiment?
cathode rays (electrons) are made of particles that have less than one-thousandth of the mass of a hydrogen atom and also found an electron that must come from inside an atom and its charge is negative
What were Thompsons findings of the atom?
- All the atoms in an element are the same
- The atoms in one element are different from the atoms in all other elements
How did JJ Thompson describe his model of the atom?
plum-pudding - a positive mass with negative electrons embedded in it
Who were the 2 scientists that helped Rutherford with his experiment?
Hans Geiger, Ernest Marsden
How did Ernest Rutherford describe his model of the atom?
atom is made of a tiny, positively charged nucleus with electrons around the outside
What were Rutherford’s findings of the atom?
- Almost all of the mass of the atom was in the nucleus
- Most of the atom is empty space
What about Rutherford’s experiment invalidated the plum-pudding model?
some alpha particles passed straight through the gold foil
What was the issue with Rutherford’s model of the atom?
you would expect electrons to spiral into the nucleus
What did Niels Bohr suggest about the atom?
electrons could only move in fixed orbits, called electron shells, around the nucleus
