History of Atoms Flashcards
who was Democritus?
a greek philosopher
what was Democritus’s theory?
that all substances contained a tiny indestructible particles called atoms
when did Democritus suggest this?
400 BC
what was John Dalton’s theory?
all matter consisted of tiny particles called atoms
atoms could not be divided into smaller particles
atoms of the same element were alike
atoms combined in simple whole number ratios
when was John Daltons theory propsed?
1808
who was J.J. Thompson?
an english scientist
what did J.J. Thompson theory suggest?
atoms contained negatively charged particles called electrons
what was J.J. Thompsons theory called?
Plum Pudding Model
what was his theory called the “Plum Pudding Model”?
he suggested that atoms were positively charges spheres with negavetily charged electrons emended in them like fruit in plum pudding
when did the Plum Pudding Model arise?
1897
What was Lord Rutherford’s theory?
atom consisted mostly f empty space with a dense nucleus with positively charges particles in the center and negatively charged electrons orbited around then nucleus
what was the Lord Rutherford experiment called?
gold foil experiment
what was Lord Rutherford theory’s flaw?
he couldn’t explain electrons orbited around the nuclues
when was the gold experiment proposed?
1911
Who was Neils Bohr?
a scientist who studied Rutherford and modified his theory
what did Bohr’s theory suggest?
electrons orbited the nucleus at different energy levels and that electrons could move from ne level to another by gaining or losing packets of enegry
what was the flaw of Borh’s theory?
it didn’t explain the known properties of all the known properties
when did Niels Bohr theory arise?
1913
what did Erwin Schrodinger’s theory suggested?
that electrons do not move in paths around the nucleus but in waves.
is it possible to know the exact location of an electron?
no its impossible
what is the cloud of probability?
they are orbitals that are more likely to find an electron
when did Erwin Schrodinger’s theory arise?
1926
what did James Chadwick discover?
the nucleus contained particles called nuetrons and protons. Nuetrons has no charge and a mass about the same of a proton
what was the other name for John Daltons theory?
Soild sphere model
what was an another name for Ernest Rutherford’s model?
nuclear model
what was another name for Niels Bohr’s theory?
Planetary Model
what is an another name for Erwin Schoridingers model?
quantum model
