Chapter 5 Review
...the 4th century B.C.
Was the first to suggest the existence of particles, atoms
Believed these structures were indivisible and indestructible.
His ideas were not useful in explaining chemical behavior.
Lacked experimental support
o John Dalton
The modern process of discovery regarding atoms began with him.
Was an English school teacher
Unlike Democritus, Dalton performed experiments to test and correct his atomic theory.
Dalton's atomic theory
All elements are composed of tiny invisible particles called atoms
Atoms of the same element are identical. The atoms of any one element are different from those of any other element.
Atoms of different elements can physically mix together or can chemically combine with one another in simple whole-number ratios to form compounds
Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction.
Much of Daltons theory is accepted today
Except we now know atoms are divisible and can be broken down into even smaller, more fundamental particles.
o Atom
The smallest particle of an element that retains the properties of that element.
Scanning tunneling microscopes provide a visual image of individual atoms.
5.2
Three kinds of subatomic particles
o Elections
o Negatively charged subatomic particles.
o Electrons were discovered by J.J Thompson
o Thompson performed an experiment that resulted with a cathode ray, a glowing beam formed between the electrodes
o Thompson discovered the beam attracted to positive metal plates and repealed negative plates
o He proposed that the cathode ray is a stream of tiny negatively charged particles moving at high speeds.( electrons)
o He...
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