University:
Alliant International University
Course:
BIO15000 | Introduction to General, Organic, and Biological Chemistry
Academic year:

2023
Views:

353

Pages:

1
Author:

Avdullahurq

What the scientists did in chronological order - KEY. Development of the ATOMIC THEORY TIMELINE Democritus 465 BC   Greek philosopher Hypothesized that atoms cannot be destroyed, are always moving, and are invisible John Dalton 1803    Created the first real atomic theory Hypothesized that the atom was a tiny hard sphere Believed that atoms of a given element are identical Dmitri Mendeleev 1869   Suggested future elements would be discovered and fitted into the periodic table Proposed the basis of our modern periodic table JJ Thomson 1897    Discovered the electron Used the cathode ray tube in his discovery Created the “plum pudding” model of the atom Ernest Rutherford 1911    Discovered that the atom is mostly empty space Discovered that the proton had a positive charge Did the gold foil experiment Niels Bohr 1915  Created a model of the atom with electrons moving around the nucleus in fixed orbits Werner Heisenberg 1925   Uncertainty principle: A particle’s position, energy, and time can never be precisely known Worked with the Quantum Theory of the Atomic Model James Chadwick 1932   Discovered the neutron Found the missing mass of the atom’s nucleus