Theories on Atomic Structure
Greeks were the first to think that all things were made of atoms
Solid Particles without internal structure
Bohr's Theory
J.J. Thomson theory
Dalton's Theory
Came in variety of shapes and sizes
atoms are small indivisible particles
all atoms of one element are identical
totally different from those that make up other elements
believed electrons revolved the nucleus like planets revolve the sun
"constant energy." When these particles absorb energy and transition into a higher orbit excited electrons
When the electrons return to their original orbit, they give off this energy as electromagnetic radiation
Rutherford's Theory
proposed a nuclear model of the atom, in which a nucleus exists
he thought that an atom had a positively charged sphere in the center with studded with negatively charged particles he called "corpuscles"
He further postulated that the number of protons in an atom equals that of the electrons
He also hypothesized that more neutral particles exist. These have come to be known as neutrons
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Quark Theory
He thought that the charge of the positive center sphere is equal to the negative charges of the electrons
they discovered that the protons and neutrons that made up the nucleus were in turn made of even smaller particles, quarks
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Quarks come in varieties such as "up," "down," "top" and "bottom."
Protons and neutrons are formed from bundles of three quarks each: "up," "down" and "up" and "down," "up" and "down," respectively