CHEM 121A Lecture Notes - Lecture 1: Oatmeal, Dimensional Analysis, Metric System
Document Summary
Chemistry is the study of matter and the changes that matter undergoes. Matter: anything having mass and taking up space. Elements: matter made up of the same atoms. Molecule: made of two or more atoms of the same specific shape. Compound: made of two or more different elements. *compounds must have at least two kinds of atoms. Gas: not distinct volume or shape, can compress or expand. *at the molecular level spacing and interactions between molecules can dictate their molecules and behavior. Pure substance: has distinct properties and composition. Can"t be decomposed to a simpler substance. Elements arranged in order of increasing atomic numbers. Groups: vertical columns with like elements with similar properties. Elemental composition of a compound is always the same. Percent of mass = mass of part divided by mass of the whole x 100. Contains substances that retain their chemical identities and properties. Observed without change to identify and composition.
