CHARACTERISTICS OF ATOMS

Fundamentals of Chemistry DOE-HDBK-1015/1-93 CHARACTERISTICS OF ATOMS Rev. 0 CH-01 Page 1 CHARACTERISTICS OF ATOMS Chemistry is defined as the systematic investigation of the properties, structure, and behavior of matter and the changes matter undergoes. This general definition raises many questions. These questions are answered in the study of chemistry. Terms and basic concepts that help in understanding chemistry will be discussed in this chapter. EO 1.1 DEFINE the following terms: a. States of matter d. Mole b. Atomic weight e. Gram atomic weight c. Molecular weight f. Gram molecular weight EO 1.2 LIST the components of an atom, their relative sizes, and charges. EO 1.3 STATE the criterion used to classify an atom chemically. Characteristics of Matter The term states of matter refers to the physical forms in which matter exists: solid, liquid, and gas. Solids are characterized as having both a definite shape and a definite volume. In a solid, the forces that keep the molecules or atoms together are strong. Therefore, a solid does not require outside support to maintain its shape. Liquids have definite volumes but indefinite shapes and are slightly compressible. Liquids take the shape of their containers. The forces that keep a liquid's molecules or atoms together are weaker than in the solids. Gases are readily compressible and capable of infinite expansion. They have indefinite shape and indefinite volume. Of the three states, gases have the weakest forces holding their molecules or atoms together. The different states of matter have one thing in common; they can all be broken down into fundamental units called atoms.