In class assignment Draw in your notes the two pie charts in figure 2-3, page 39, of your textbook. Read pages 41 -42 in your textbook. Record in your notes the following terms and their definitions as found in your textbook. Chemical formula pure substance mixture heterogeneous mixture homogeneous mixture immiscible miscible
Chemical Formulas - The chemical symbol and the numbers indicating the atoms contained in a molecule
Pure Substance – matter with a fixed composition and definite properties • Can be an element or a compound • Cannot be broken down by physical actions such as boiling or melting • Ex: Hydrogen, Helium, Carbon, Gold, Silver, Oxygen, Nitrogen, Argon, Calcium, PotassiumEx of compounds: Methane, carbon monoxide, carbon dioxide, pure water and table salt (sodium chloride).
Mixture – a combination of more than one pure substance • Can be broken down by physical actions • Ex: sand and sugar
Ex: Is grape juice a mixture or pure substance? In chemistry grape juice is not a pure substance. It is a mixture of many pure substances like water, sugars, and acids. It can be separated.
Mixture Classification - how thoroughly the substances mix 1. Homogeneous - all parts are the same ex: salt with water brass – mix of copper and zinc 2. Heterogeneous – not all parts are the same ex: sand and water
Miscible vs. Immiscible Pertains to liquid mixtures miscible – 2 or more liquids that dissolve into each other immiscible – liquids that do not dissolve
Chemical formulas show how many atoms of each element are in the basic unit of a substance. • Number of atoms is written as a subscript • Ex: C6H12O6 • means: 6 atoms of C (carbon) • 12 atoms of H (hydrogen) • 6 atoms of O (oxygen) • No subscript means 1 atom present • Ex: H2O not H2O1
Number in front shows the number of molecules. • Ex: 2 AgNO3 (silver nitrate) • 2 molecules of silver nitrate • 2 atoms of Ag (silver) • 2 atoms of N (nitrogen) • 6 atoms of O (oxygen)
Sometimes groups of atoms act as a single atom and they are put in parentheses with a subscript. All elements in the parentheses should be multiplied by that subscript. Fe(OH)3 (iron) 1 atom of Fe 3 atoms of O 3atoms of H
Ex 1: C16H10N2O2 (indigo dye) 1 molecule of indigo 16 atoms of C 10 atoms of H 2 atoms of N 2 atoms of O
Ex 2: 3 C12H22O11 (table sugar) 3 molecules of sugar 36 atoms of C 66 atoms of H 33 atoms of O
Homework: Review pages 38 – 44 Complete problems 1 and 2 on page 43 Complete problems 1-8 on page 44