Chapter 1: Essential Ideas

Chapter 1. Essential Ideas. Section 1. Chemistry in Context Chemistry-study of the composition, properties & interactions of mutter The Scientific Method 1) Observe & formulate a question. 2) Hypothesize. hypothesis-a testable explanation of an observation 3) Experiment & observe some more.. 4) If results are consistent with prediction, make a note & continue testing. 5a) If additional testing constant observation, you have a law. law-a statement that summarizes almost any observation & describes/predicts. any fuct of the natural world. 5b) If additional testing satisfied hypothesis, you have a theory. theory (scientific) - comprehensive, testable explanations that can be medified if new duta become available macroscopic domain-the une seen with the naked eye microscopic domain-the one that can only be accessed through microscopes (& sometimes only through the imagination) Symbolic domain-the specialized language used to represent components of hith domains (chemical symbols/formulae/equations/etc.) Section 2: Phases and Classification of Matter matter-anything that has mass & takes up space solid-rnigid structure of matter that possesses a definile shape. liquid- matter that flows & takes the shape of its container gas-matter that takes both the shape & volume of its container plasma-gaseous state of matter that is electrically charged mass-the amount of matter in a particular object weight-the force that gravity exerts on a particular object law of conservation of matter; matter is neither created nur destroyed just converted to a different state (or states) ene thut pure substance-hus a constant composition throughont element-pure substances that cannot be broken down further compounds-pure substances that CAN be broken down by chemical changes (into elements) mixture-composed of two of mere types of matter that can be present in varying amounts & can be separated by physical changes. heterogenous-describes a mixture one whose composition varies from print to point →homogenens-describes a mixture that exhibits uniform composition thronghant (AKA solution) atom -the smallest particle of an element that has properties of that element 5th century BC: Greek philosophers Leucippus & BDemocritus suggested. mutter was composed of smaller particles (atom) Early 19th century AD: Juhn Dalton, British schoolteacher, suppusted the hyputhesis of the existence of atums molecule-two or more atoms joined by chemical bands Section 3: Physical and Chemical Properties. physical property-characteristic of matter not associated with chemical composition (EX: boiling/melting point, density, color) chemical property-change of one type of matter into another type (Ex: Flammability, toxicity, acidity, reactivity) physical change-change inttestate of matter w/o changing chemical identities. (Ex. ice melting, suger dissolving in cuffer, grinding solids into powders) chemical change -produces une or more types of matter different from the initial une. (EX: explosion of nitroglycerin, food rutting, electrolysis) extensive property-those that depend on the cate amount of matter present (EX, muss & volume) + heat transfer intensive property - those that do not depend on amount of matter present (EX. temperature) Would molecular muss count as an intensive property or not? intensive Chapter 2: Atoms, Molecules, and Ions Section 1 5th century BC: Greek philosophers Lencippus and Democritus pustulated that all matter was composed of small, finite particles 1807 AD: Juhn Dalton (uf England) publishes his Atumic Theory- Dalton's Atomic Theory: - Matter is composed of atoms, which are the smallest possible units of an element. -An element unly consists of one type of atom, and that une types of atom hos a muss particular to its element.. - Moms of une element differ in properties from atoms of all elements. - A compound consists of atoms of toro or more elements combined in a whole-number ratiu. In a given compound, its atoms are always present in that same ralia. -Atoms ure neither created nor destroyed during chemical changes Law of Definite Proportions; all samples of a pure compound contain the same. elements in the same prepuction by mass Law of Multiple Proportions when two elements react to form miele than une compound, a fixed mass of une element will. react with the mass of the other in small, whole-number ratios.