History of Atomic Theories - History of Atomic Theories 1...

This preview shows page 1 - 4 out of 11 pages.

History of Atomic Theories 1History of Atomic TheoriesJohn-Douglas McGregorSCH4USomayeh NikoudadAugust 14th, 2014
History of Atomic Theories 2History of Atomic TheoriesThis essay is an analysis of the significant Atomic Theories that lead to the ModernAtomic Theory, the basis of chemistry (Barron's E-Z chemistry, 2009). The following pages willexamine five different philosophers, theories: Democritus, John Dalton, J.J. Thompson, ErnestRutherford, Neils Bohr, ErwinSchrödinger and James Chadwick.Democritus Atomic Theory:The main idea of philosopher Democritus, who lived more than 2000 years ago, was thatan atom is an invisible and indestructible particle. Democritus was a man of Greek origin, so herelated his work back to his origins. For example the wordatomosin ancient Greek means “thatwhich cannot be further broken down into smaller pieces.” (Lista, 2006) Democritus made 6basic assumptions, known as theparticle theory of matter.Particle theory of matter(Lista, 2010):1.Matter is made up of tiny particles (Atoms & Molecules)2.Particles of Matter are in constant motion.3.Particles of Matter are held together by very strong electric forces4.There are empty spaces between the particles of matter that are very large compared tothe particles themselves.5.Each substance has unique particles that are different from the particles of othersubstances6.Temperature affects the speed of the particles. The higher the temperature, the faster thespeed of the particles.Democritus theory like most philosophers of his time was not based on scientificexamination/experiments. It was based on reasoning and assumptions.Some shortcomings/problems with Democritus theory are that it does not give a specificview of the atom only a theoretical definition and that it does not discuss subatomic particles(electrons, neutrons, and protons).Democritus short comings left the way open for furtherdevelopment on his theory.John Dalton Atomic Theory:
History of Atomic Theories 3Theories based on non-experimental trials continued until the eighteenth century. Duringthe eighteenth century scientific experimentation was on the rise and in 1805, John Dalton madesome of his own assumptions about atoms. The difference between Dalton and Democritusassumptions is that, Dalton had experimental data to support his assumptions, and for this reasonis often identified as the father of modern atomic theory (Francis, 2002).Dalton’s theory makes 5 main assumptions, known as the theory of simple multiple proportions(Francis, 2002).Dalton’s Atomic Theory (Theory of Simple Multiple Proportions):1.All matter is made from tiny hidden particles, called Atoms.2.All Atoms of a specific element are the same in weight and has a unique weight whencompared to other atoms.

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 11 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Fall
Professor
N/A
Tags
History, Atom, Electron, atomic theories

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture