Chemistry Chapter 4 Atomic Structure

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4.1

Early Model of the Atom

A. How can you believe in something that you can't see.

B. Democritus's atomic philosophy, 460 BC - 370 BC

1. Atoms were indivisible and indestructible

2. No scientific evidence or support

Dalton's atomic theory

A. John Dalton -1766-1844

1. English chemist and school teacher.

2. Using experimental methods, he transformed Democritus's ideas on the atom into a scientific theory.

The theory:

1. All elements are composed of tiny indivisible particle called atoms

2. Atoms of the same element are identical.

3. Atoms of different elements can physically mix together or can chemically combine in simple whole number ratios

4. Chemical reactions occur when atoms combine, but never change into atoms of another.

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