1. making compounds from atoms Or making stuff from other stuff
CHEMICAL REACTIONS
making compounds from atoms Or
making stuff from other stuff

2. The Law of Conservation of Matter
This law states that
Matter cannot be created or destroyed, therefore
During a chemical reaction you must end with the same amount of stuff that you started with

3. What’s Happening?
During a chemical reaction, electrons from one atom are either a) being shared with another atom or b) being donated to another atom
In either case this causes the two atoms to bond together to form a compound
A compound is when two or more atoms bond together

4. The resulting compound has completely different properties than either of the beginning products
Na (sodium) is a metal. It reacts violently with water and explodes.
Cl (chlorine) is a deadly poisonous gas.
When they react with each other, the product is NaCl (sodium chloride) which is simply table salt.

7. Watch reaction

8. 2 Types of Reaction Covalent bond
This is when electrons are shared between atoms
This type of bond forms between two non-metals
Examples: H2O, CO2

9. Ionic bond
This is when electrons from one atom are donated to the other
This forms two ions. (What’s an ion?) One is positive and one is negative
The two ions are attracted to each other because of their opposite charges
This type of bond forms between a metal and a non-metal
Examples: CaCl2, KI, NaCl

10. Let’s try an easy one To make water you need…
Correct, hydrogen and oxygen
Now, in reality both of these gases exist in diatomic form so they look like this
H2 and O or

11. this

12. So if these two gases are to react, the diatomic form will be involved
To represent this reaction we write the molecular formulas in an equation like this
H2 + O2 
The arrow is kind of like an equals sign in math except that you would read it like, “H2 plus O2 yields…” Get it?
What does hydrogen and oxygen make again?
Oh that’s right, water

13. What’s the chemical formula for water?
Oh yeah H2O……soooooo….
H2 + O2  H2O (H2 + O2 yields H2O)
But wait…something’s wrong!
What did that law say?
That’s right!

14. H2 + O2  H2O How many hydrogens are on the left? Correct, there are 2
How many are on the right?
So we’re obeying the law so far
What about the oxygens?
There are___on the left and___on the right….
uh oh. Now what?

15. Now We Have to Balance It!!
Balancing equations is just a way for us to try to figure out what is happening
We manipulate the numbers until it makes sense based on the Law of Conservation of Energy
As we stated it, H2 + O2  H2O, implies that 1 diatomic hydrogen molecule reacts with 1 diatomic oxygen molecule to make 1 water molecule
But mathematically, this can’t be because we lost an oxygen and that’s against the law

16. Luckily this is on paper or the computer so..
…we can change stuff around until it makes sense
This is called balancing the equation
To balance you place coefficients in front of the chemical symbols until the reaction obeys the law
Let’s get back to our equation

17. ___H2 + ___O2  ___H2O
So, the problem was the oxygen. Let’s start there.
What coefficient, placed in front of the H2O will make it obey the law?
Correct, a 2
___H2 + ___O2  2H2O
Alright, so 2 oxygens on the left and 2 x 1 oxygens on the right, that makes 2. Everything’s good. No wait a minute…
Uh oh…Now how many hydrogens are on the right?
What’s 2 x 2?
Correct, there are 4
How many hydrogens are on the left?
What do we do?

18. CORRECT!
We put another coefficient in front of the H2 to balance that.
2H2 + ___O2  2H2O
Now is it right? Check the numbers. How many on the left and how many on the right?
See?
Now its balanced, so we can say that 2 diatomic hydrogen molecules react with 1 diatomic oxygen to form 2 water molecules.
Or, 2 H2’s plus 1 O2 yields 2 H2O’s

19. So what does all this look like?
What’s really going on?
2H2 O2
2H2O