Download The Development of the Atomic Theory

The Development of the Atomic Theory
Name _________________________ Date ____________ Period ___________
The philosophic idea of atoms has existed since 4000 BC when Democritus proposed the idea that matter is
made of tiny particles called atoms. The Greek term “atomos” means atom.
Because Aristotle rejected the idea of the atom, it was lost for approximately 2000 years.
Models:
Models help explain the unseen and can be verbal, visual, or mathematical. Using your presentation notes, fill in the
blanks about the development of modern atomic theory.
In the mid to late 1600’s _______________________ defined elements as__________
___________________________________________________________________.
In the early1800’s, ______________________ proposed the atomic theory. This theory had five basic parts:
(A) ___________________________________________________________________
(B) ___________________________________________________________________
(C) ___________________________________________________________________
(D) ___________________________________________________________________
(E) ___________________________________________________________________
Dalton’s model of the atom is known as the _______________________________ model.
By the late1800’s, subatomic particles were being discovered. Using a cathode ray tube, __________________
(1897) discovered that all elements had ______________charged particles termed __________. He
developed the ____________-______________ model that described the atom as having
negatively charged electrons embedded in a ball of positive charges. The discovery of the electron
was a blow to Dalton’s indivisible atom. Why? ___________________________________________
The first periodic table of elements was developed by ________________________ around 1863. In
1865 he noted that every eighth element had similar properties. He called this the
________________________________.
In 1868, __________________________ related the then known 60 + elements in a systematic, logical
fashion on a __________________ _____________ with the elements arranged in
order of increasing _______________ ______________. Interestingly, he left blank
spaces for yet to be discovered elements.
Around 1903, French chemist, ____________________________ observed that uranium
salts created shadows on photographic plates which led to the discovery of radiation by
________________________________. They shared the Nobel Prize for this discovery.
Around 1909, American scientist, _________________________, conducted experiments to
determine the quantity of charge of the ____________________. His most famous experiment is
the __________________________ which also allowed him to accurately calculate the mass of an electron.
In 1911, Ernest Rutherford performed the classic ____________ ____________ experiment
which showed that the atom is _______________________________________________________
_________________________________________The positive charges are called ______________
This model was called the ____________________ model or ________________ model of the atom.
The periodic table we use today is arranged by ________________ _______________ and was
developed by ______________ ______________ around 1913. He determined the number of
____________in the nucleus of an atom by _______________________________________.
Also around 1913, _______________________ introduced his model of the atom which showed the
electrons traveling in orbits around the nucleus. This is known as the _____________ or
_________________________ model.
In 1932, James Chadwick confirmed the existence of the ____________ which had no
_____________ and nearly the same mass as a ______________. It is located in the
__________________ of the atom thus solving the mystery of the “extra mass” in atoms.
Along with Einstein, Planck, ________________________________ and _____________________
contributed to the modern quantum model of the atom with the concept of ____________________________.
In fact, the “wave equation” is named for __________________________ which quantized the energy of electrons.