John Dalton (1766 – 1844) proposed a basic model of the atom that helped establish many scientific concepts and also created the foundation for more modern models. His model suggested that atoms are the smallest particle of an element, that atoms of different elements have different masses, and that they are solid, indestructible units - much like a billiard ball .He called his model the " Billiard Ball model" because he thought that atoms looked like billiard balls from pool. Dalton’s Atomic Theory included five main points. Atoms:
Make up all matter.
Cannot be subdivided, created, nor can they be destroyed. They can simply be rearranged into different groups.
Of a given element are identical, while atoms of different elements vary and can be distinguished from one another using their respective weights.
Combine with or separate from other atoms to form compounds in chemical reactions.
Of different elements form compounds in whole number ratios Dalton’s Theory also supported three physics concepts:
His theory stated that in chemical reactions, atoms are neither created nor are they destroyed, which clearly enforces the Law of Conservation of Matter. Dalton also provided evidence that a pure compound is always composed of identical elements and always has the same mass. This corresponds to the Law of Definite Composition. Lastly, Dalton's theory explains the Law of Multiple Proportions: Atoms combine in whole number ratios to form compounds and if these proportions differ, so will the compound. However, the modern Atomic Theory provides evidence that disproves some of Dalton's Theory: 1.
Atoms of the same element can differ (isotopes and ions). 2.
Atoms are divisible.
we know atoms are made of smaller parts, and you can break them down in nuclear (not chemical) reactions, but overall Dalton set up a great base of knowledge for the next group of atomic scientists to build on.
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