Post on 13-Dec-2015
Atomic TheoryGrade 9 Science
Theories and Laws
What’s the difference between a theory and a law??
LawsDescriptions of events or patterns that have been observed over long periods of time
Do not involve an explanation, simply state what happens
Theories
Explain observations that are supported by experimental evidence
Can change if new evidence becomes available
Development of the Atomic Theory
Men and women from different countries have contributed to our understanding of the atom
Early Greeks contributed to the Atomic Theory
Empedocles: http://en.wikipedia.org/wiki/Empedocles
Democritus:http://www.timelineindex.com/content/view/1228
Aristotle: http://cstl-csm.semo.edu/mcgowan/ch181/atomhist.htm
John Dalton1766 - 1844
Dalton Atomic Theory
State the 4 points of Daltons Atomic Theory:1
2
3
4
JJ Thomson1856 - 1940
Atoms composed of small particles
Atoms contain negatively charged particles called electrons
Raisin bun model
Ernest Rutherford1871 - 1937
Conducted “Gold Foil Experiment”
Realized large space within atoms
Discovered the nucleus of the atom
Established that the nucleus had 2 types of particles: proton (+) and neutron (0)
Gold Foil Experiment
Positive particles
Neils Bohr1885 - 1962
Studied the area around the nucleus
Area around nucleus contained electrons (-)
Ran electric current through gas and observed the gas glowing brightly
Proposed electrons surround nucleus in specific energy levels
Bohr’s Model Glowing Neon Gas
Study the structure of the Atom with its three sub-atomic particles