Warm-Up Name one physical change and one chemical change that can happen to a book. Complete sentences! DON’T TURN IN YESTERDAY’S WORKSHEET!

Agenda Review Physical and Chemical properties worksheet Collect WS Safety Video: https://www.youtube.com/watch?v=V-fNpaOX0-g Identify unsafe behaviors Lab Safety Questions (quiz Thursday) Notes: Elements and Compounds HW: Elements and compound naming

Elements & Compounds

Elements Pure substance One kind of atom 118 elements 91 exist naturally 27 are synthetic (manmade), most of which are radioactive Cannot be chemically broken down

Element Symbols All can be found in the Periodic Table Some elements are diatomic molecules in their natural state, meaning they contain 2 atoms. H2, F2, Cl2, Br2, I2 Cu Ag Au Ne N2 O2 Ca Al

Compounds Pure substance Molecules that contain 2 or more different elements Can be chemically broken down Properties are vastly different than the properties of the elements that make it up H2O C12H22O11 C2H5OH NaCl

Compound Formulas Subscript – gives the number of atoms of each element in the compound Practice: HCl Na3PO4 Ba(OH)2 Al2(SO4)3 (NH4)2Cr2O7 CH3COOH

Compound Formulas H2O H2O2 Changing the ratio of atoms in a specific compound forms a new compound with completely different properties. H2O H2O2 Water Clear & colorless Necessary for life Boiling point = 100oC Density = 1 g/mL Hydrogen peroxide Clear & colorless Toxic if ingested Boiling point = 150oC Density = 1.11 g/mL