Do Now: Take out notebook, homework, and pencil Why is Na an element and NaCl a molecule?

Macaroni Salad Engagement Video What is the smallest part of matter? What are molecules made of?

Glue the notes page onto page 51

Molecules A group of atoms bonded together, representing the smallest unit of a chemical compound Made up of two or more atoms The atoms can be the same or different Examples of molecules: O2 – oxygen gas O3 – ozone gas H2O - water molecule CO2 – carbon dioxide H2SO4 – sulfuric acid Notice how some molecules are more complex than others

Compound A chemical compound is a chemical substance formed when two or more different elements bond The elements lose their individual chemical properties and the compound has new properties. Chemical bonds are a result of the sharing or exchange of electrons among the atoms 2 Hydrogen atoms 1 Oxygen atom Water Molecule

Quick INB Action – Molecules Practice Element Molecules Compounds 1. Quickly sketch the 3 circles 2. Draw each object in the correct circle. © KeslerScience.com

Quick Action – Molecules Practice Grab a partner and let’s practice. Is it a molecule or a compound? Formula Molecule Compound Element Both Compound and Molecule O2 NaCl CH4 H2 H https://www.youtube.com/watch?v=VOQzWLeZoEc Atoms elements and compounds This would be a good short video to show at this time. Write a rule that you can follow for determining the difference in a compound and a molecule? Here is a hint… All ___________ can be ___________, but….. © KeslerScience.com

Chemical Formula The recipe for a chemical substance Tells the number of atoms of each element in a compound or molecule Uses symbols for the elements present as well as how many there are in the form of subscripts Chemical formula for water: H2O (circle the subscript)

Chemical Equation A chemical equation is a shorthand way scientists use to describe a chemical reaction In writing chemical equations the large number in front of a molecule’s symbol indicates the number of molecules participating in the reaction. This number is called the coefficient If no coefficient appears then only one molecule is present 2 H2 + O2 → 2H2O Number of hydrogen molecules: 2 Number of oxygen molecules : 1 Number of water molecules: 2

Quick Action – Molecules Practice Grab a partner and let’s practice. Count the molecules in each balanced equation. 1. CH4 + 2O2 CO2 + 2H20 _____ CH4 _______ O2 _______ CO2 _________H20 2. 2Fe +3Cl2 2FeCl3 _____ Fe _____ Cl2 _____ FeCl3 3. P4O10 + H2O 4H3PO4 _____ P4O10 ______ H2O _____ H3PO4 1 2 1 2 2 3 2 1 1 4 © KeslerScience.com