CHEM 111 Lecture Notes - Lecture 2: Stoichiometry, Human Body, Evaporation

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14 Sep 2016

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Document Summary

The properties of matter depend on the types and arrangement of atoms and molecules: nomenclature, stoichiometry, physical change vs. chemical change, energy. Matter can be classified as substances and mixtures. Elements are the most basic units of matter. They are composed of only one type of atom. They cannot be broken down into smaller units by chemical means. They are the things on the periodic table. There is a total of 118 elements and 90 of them occur naturally. Earth crust made up of oxygen, silicon, aluminum, iron, and calcium. Human body made up of oxygen, carbon, and hydrogen. Compounds consist of two or more different atoms bonded together in a defined ratio. They can be broken down into smaller units by chemical means. All compounds are molecules but not all molecules are compounds. Atoms are the smallest chemical unit of matter (indivisible unit of an element). Molecules are formed when two or more atoms are chemically joined together.

Related Questions

With some modifications of Dalton's atomic theory, these postulates hold up very well regarding how we view elements, compounds, and chemical reactions today. Answer the following questions concerning Dalton's atomic theory and the modifications made today.

a. The atom can be broken down into smaller parts. What are the smaller parts?

b. How are atoms of hydrogen identical to each other and how can they be different from each other?

c. How are atoms of hydrogen different from atoms of helium? How can H atoms be similar to He atoms?

d. How is water different from hydrogen peroxide, , even though both compounds are composed of only hydrogen and oxygen?

e. What happens in a chemical reaction and why is mass conserved in a chemical reaction?

bronzealligator355

Section 1-5 describes the postulated of Dalton's atomic theory. With some modifications, these postulates hold up very well regarding how we view elements, compounds, and chemical reactions today. Answer the following questions concerning Dalton's atomic theory and the modifications made today.

a. The atom can be broken down into smaller parts. What are the smaller parts?

b. How are atoms of hydrogen identical to each other and how can they be different from each other?

c. How are atoms of hydrogen different from atoms of helium? How can H atoms be similar to He atoms?

d. How is water different from hydrogen peroxide (H₂O₂) even though both compounds are composed of only hydrogen and oxygen?

e. What happens in a chemical reaction and why is mass conserved in a chemical reaction?