Dalton Teacher Sheet

Dalton Teacher Sheet By Henry Roscoe (author), William Henry Worthington (engraver), and Joseph Allen (painter) [Public domain], via Wikimedia Commons


Students should use the resources on the Dalton student esheet to explore the key links, glossaries, and other broader resources on John Dalton. They should answer the questions on the Dalton student sheet. This sheet provides you with answers to the questions.

What is the difference between physical and chemical atomism?
Physical atomism refers to the structural parts, forces, and properties of an atom. Chemical atomism refers to “the manner in which different elements relate and the new substances they form by their union.” Students need to note that Dalton’s work dealt with chemical atomism and that advances in physical atomism came well after his death.

How did Dalton come to develop his chemical atomic theory?
It is believed that he arrived at his theory through his studies and experiments in meteorology, specifically in the areas involving vapor pressure, gas solubility, and gas mixtures.

What did Dalton ultimately wish to determine or prove?
In his experiments, he wanted to prove his hypothesis that “the sizes of particles making up different gases must be different.” Further, he ultimately wanted to determine the sizes, weights, and numbers of all chemical particles involved in any kind of chemical combination (reaction).

What are the four basic ideas of Dalton’s chemical atomic theory?
They are: “(1) chemical elements are made of atoms; (2) the atoms of an element are identical in their masses; (3) atoms of different elements have different masses; and (4) atoms only combine in small, whole number ratios such as 1:1, 1:2, 2:3 and so on.” 

Where, if any, was the work of Dalton proven to be incorrect?
His second idea that all atoms of an element have the same weight was later proven to be incorrect when isotopes were discovered.

What is seen as the “original contribution” of Dalton?
Dalton was the first scientist to devise a system that effectively determined the atomic weights of elements. Students need also be aware that Dalton was the first to use standard symbols for elements.

What is the Law of Conservation of Mass?
An idea credited to Lavoisier, this law holds that “atoms can be neither created nor destroyed. An element's atoms do not change into other element's atoms by chemical reactions.”

What is the significance of Dalton’s work?
His key concepts—“that chemical reactions can be explained by the union and separation of atoms and that these atoms have characteristic properties”—became fundamental principles of modern physical science.

This teacher sheet is a part of the The History of the Atom 2: Dalton lesson.

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