Compare and contrast CO2 and O2 Do now: Compare and contrast CO2 and O2 Use the following words: element compound molecule atom Source: Region 4 Warm Up to Science

Compare and contrast CO2 and O2 Are alike in that both molecules are made of elements CO2 is a compound because it contains more than one type of atom while O2 is an element because it is made of only one type of atom CO2 is made of 3 atoms chemically joined together while O2 is made of 2 atoms chemically joined together Source: Region 4 Warm Up to Science

How do we know if we have a chemical reaction???? Chemical Reactions How do we know if we have a chemical reaction????

Signs of a chemical REACTION Has a formula explaining what is happening. Gives off a gas – look for bubbles! Gives off light - Fireworks! Gives off heat - What’s this called? Makes a precipitate – a solid at the bottom! Changes color Can’t change back easily original material

Two Words to KNOW When talking about chemical reactions Endothermic – gets colder ( heat goes in – enter) Exothermic – gets hotter ( heat goes out – exit) Have students draw a picture to remind them of endo and exo as enter and exit of heat!

Coefficients 2Mg + O2  2MgO Reactant Product Subscript We use chemical equations to show what is happening with a chemical reaction Coefficients 2Mg + O2  2MgO Reactant Product Subscript Label their papers with vocabulary words

Chemistry Terms to Know Reactants – chemicals on the left side that we are mixing together Products – chemicals that we create Coefficient – Big number in front – tells us how many molecules I have of a chemical. Subscript – small number below tells us how many atoms of just one element I have. Yield – the arrow Write down definitions to use later

Figure out the number of atoms in these formulas Example CaCl2 1 Ca 2 Cl Focus on using vocabulary words Subscript is 2 tells how many atoms of Cl there are If there is no number present Ca that means there is one!

Now lets add in Coefficients Example: 3H2O The 3 in front says we have 3 molecules of water So we have 6 H and 3 O Coefficient is the number in front. They work like math 3 times the whole thing 3 x 2 = 6 H 3 x 1 = 3 O

Using what you know, determine if these chemical equations are balanced or not. A balanced equation should have the same number of chemicals on both sides.

Source: TAKS 8 Study Guide, pg. 64

NaCl CO2 H3PO4 Fill in the chart: Chemical Formula Total # of Elements in the Formula Total # of Atoms in the Formula NaCl CO2 H3PO4 Source: Region 4 Warm Up to Science

Is this a balanced equation? Study the following chemical equation and then fill in the chart: 2Ag + H2S  Ag2S + H2 Products Reactants 2 silver (Ag) atoms 1 sulfur (S) atom 2 hydrogen (H) atoms Is this a balanced equation? Source: Region 4 Warm Up to Science

Source: TAKS 8 Study Guide, pg. 65

Work problems to determine if they are balanced or not.