Use the following words:–element–compound–molecule –atom

Source: Region 4 Warm Up to Science

Compare and contrast CO2 and O2

Do now:

• 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

Compare and contrast CO2 and O2

Chemical ReactionsHow 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 KNOWWhen talking about chemical reactions

Endothermic – gets colder ( heat goes in – enter)

Exothermic – gets hotter ( heat goes out – exit)

We use chemical equations to show what is happening with a chemical reaction

Coefficients2Mg + O2 2MgO

Reactant ProductSubscript

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

Figure out the number of atoms in these formulas

Example CaCl2

1 Ca 2 Cl

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

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

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

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.