Chemical reactions Chapter 13.2

Standards: GLE 0807.9.4 Distinguish among elements, compounds, and mixtures. GLE 0807.9.8 Interpret the events represented by a chemical equation

Key concepts: Interpret and write simple chemical formulas Identify the reactants and products of a chemical reaction.

Key Vocabulary: Chemical formula Chemical equation Reactant Product

What do you already know? Imagine having to write out ten million, one hundred thousand, two hundred and three plus two! Now imagine having to write out names! Why do you write with numbers (1,2,3, 10,100,203) than writing out their names? In chemistry we use short-hand as well. A chemical formula is a way of writing out what happens in an experiment What is H20? Or CH4 http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/75482.htm http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/75108.htm

Let’s talk compound vs. element: Is it a compound or element? He

Let’s talk compound vs. element: Is it a compound or element? How many atoms? CO2

Let’s talk compound vs. element: Is it a compound or element? How many atoms? NaClO

Let’s talk compound vs. element: Is it a compound or element? How many atoms? Na

Let’s talk compound vs. element: Is it a compound or element? How many atoms? (CH3)2CHOH

So remember this! Bonding Ionic Metal and non-metal Charges have to cancel out when making the compound! Covalent Non-metal bond to non-metal Sharing until the outer ring is full!

Chemical Formula: What does shorthand mean? How many atoms? -H20 -C6H1206 -CH4 A chemical formula is a shorthand way to use chemical symbols and numbers to represent a substance. Also shows how many atoms are in each kind of molecule Important parts: Elements symbol Subscripts Coefficients

Chemical Formula continued: What does shorthand mean? How many atoms? -H20 -C6H1206 -CH4 Read page 339 Important parts: Elements symbol—you know this already! Subscripts Number written below and to the right of the symbol Stands for the number of atoms of that type of element O2 CO2 N2O

Chemical Reaction: Think of this a piece of sheet music... Cheat sheet time! Reactants point to products R  P Chemical equation uses symbols and formulas to describe a chemical reaction. Parts: Reactants—starting materials Products—what you make Yield—this is the arrow sign This usually means that energy is going in or out

H2O(l) + SO2(g)  H2SO3(g) Identify the part: Is it a reactant or product? How did you know? H2O(l) + SO2(g)  H2SO3(g)

Identify the part: Is it a reactant or product? How did you know? How many oxygens on this side?

NaHCO3 + CH3COOH CH3COO-Na+ + H2O + CO2 Identify the part: Is it a reactant or product? How did you know? NaHCO3 + CH3COOH CH3COO-Na+ + H2O + CO2

C3H8 + 5 O2  3 CO2 + 4 H2O Identify the part: Is it a reactant or product? How did you know? C3H8 + 5 O2  3 CO2 + 4 H2O

Pearls of Wisdom: On your small sheet of paper, please list what you learned today. Do you think you can tell me what I wanted you to learn?

Homework: Have a great weekend!

Pancakes!