Presentation on theme: "Cook. At the end of the 19 th Century, scientists began to probe the submicroscopic world of atoms Development of atomic models John Dalton: Thought."— Presentation transcript:
At the end of the 19 th Century, scientists began to probe the submicroscopic world of atoms Development of atomic models John Dalton: Thought the atom was to be considered to be a solid indestructable mass. He developed the Atomic Theory
All atoms are composed of tiny indivisible particles called atoms Atoms of the same element are identical. The atoms of any one element are different from those of any other atom Atoms of different elements can combine with one another in simple whole number ratios Chemical reactions occur when atoms are separated, joined or rearranged
Discovered the electron using cathode ray experiment Electron e - 1 - 9.11x10 -23 Proton p + 1 + 1.67x10 -24 Neutron n + 0 1.67x10 -24 http://www-outreach.phy.cam.ac.uk/camphy/electron/electron4_1.htm This lead to the discovery of atomic models Plumb pudding model
The discovery of the electron lead to many different models of the atom Plum Pudding model Negatively charged electrons stuck in a lump of positively charged protons. Didn’t explain neutron Rutherford’s Model Nuclear atom in which electrons surround a dense nucleus, and the rest of the atom is empty space Bohr’s Model Electrons are arranged in concentric circular paths, sort of like the planets
See Page 246 Be able to differentiate between the following: Thompson model Rutherford’s Model Bohr Model Quantum Mechanical Model
Refer to Bohr’s model (it’s the most commonly accepted) All electrons have fixed energy They do not lose energy and fall into the nucleus Energy Level: Is the region around the nucleus where it is likely to be moving. Like rungs on a ladder Lowest rung has the lowest energy level Energy levels increase as u move up the ladder
The amount of energy gained or lost by every electron is not the same Unlike rungs on a ladder, the energy levels in an atom are not equally spaced Quantum: Is the amount of energy required to move an electron from it present energy level to the next
Erwin Schrodinger took atomic models a step further He used the quantum theory to write and solve mechanical equations describing the location of the electron Quantum Theory Quantum theory is the theoretical basis of modern physics that explains the nature and behavior of matter and energy on the atomic and subatomic level.
A modern description of electrons in atoms. It is based on mathematical equations.