Chapter 4 and %

An atom is the smallest particle of an element that retains its identity in a chemical reaction.

How did Democritius describe atoms?

He believed that atoms were indivisible and indestructable.

His ideas agreed with later scientific theory, they lacked support of chemical behavior.

How did John Dalton further Democritis's ideas on atoms?

By using experimental methods, Dalton transformed his friends ideas into a scientific theory.

The result was Dalton's Atomic Theory.

Idea #1

All elements are composed of tiny things called atoms.

Idea #2

Atoms of the same element are identical. The atoms of any one element are different from those of any other element.

Idea #3

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

Idea #4

Chemical reactions occur when atoms are separated, joined or rearranged. Atoms of one element are never changed into atoms of another element as a result of a chemical reaction.

Three kinds of subatomic particles are electrons, protons and neutrons.