The Solid Sphere Model
By the early 1800’s, the Law of Definite Composition and the Law of Multiple Proportions were commonly accepted
ideas concerning the behavior of matter.
- Law of Definite Composition states that in any sample of a compound the masses of the
elements are in the same ratio.
- Law of Multiple Proportions states that when two elements combine to form more than one
compound, the fixed amounts of one element will combine with the other in a ratio of small whole numbers
Influenced by these concepts, John Dalton, a Quaker tutor, took these ideas and the work of
others and devised the first atomic model based on empirical evidence.
- All matter consists of tiny, indivisible, indestructible particles called atoms.
- Atoms of the same element have the same size, mass and chemical properties.
- Differences in the properties of elements result from differences in the atoms of the elements.
- The atoms in a compound combine in a definite, simple, whole number ratio.
- A chemical reaction is the result of rearrangement, combination, or separation of atoms.
“We might as well attempt to introduce a new planet into the solar system,
or to annihilate one already in existence, as to create or
destroy a particle of hydrogen.” – John Dalton