1. Chemical Reactions Intro

2. -practice balancing worksheet
When you are balancing a chemical reaction, do you change the coefficients or subscripts?
Identify how many atoms are in the following molecule: 3PO4.
Label the products and reactants in the following equation.
N 2 + H2  NH3
Warm-Up
Agenda:
-warmup
-notes
-practice balancing worksheet

3. WarmUp Name the 3 subatomic particles found in an atom.
Please take a NEW warmup sheet AND table of contents from the front table!
WarmUp
Name the 3 subatomic particles found in an atom.
Which of these three are the ONLY particles involved in chemical bonding?
Describe the difference between ionic and covalent bonding.
Proton, neutron, electron
electron
Ionic: transfer of electrons
Covalent: sharing of electrons

4. Intro to chemical reactions

5. Chemical Reactions
Occur when there is a transfer or sharing of electrons
Chemical reactions occur when two chemicals unite or react to form a compound that is unlike the original substances and cannot be changed back to its original form.
When a chemical reaction occurs, the substances involved undergo a chemical change

6. Chemical Changes Evidence of chemical change:
bubbling (formation of gas)
turning cloudy (formation of a new solid)
temperature change (heat or light released)
color change (formation of a new solid)

7. Chemical Reactions
In chemical reactions you start with reactants that are combined into products.
The reactants and products may include atoms, molecules, and energy.

8. Chemical Reactions
The formation of rust from oxygen and iron is an example of a common chemical reaction.

9. Chemical Reactions Chemical reactions proceed in two stages.
1. First, the chemical bonds must be broken between the atoms in the reactants.
2. In the second stage, new bonds form between atoms to make the products of the reaction.

10. Activation energy
The energy needed to break chemical bonds in the reactants is called the activation energy of the reaction.
A spark supplies the activation energy to start the reaction between hydrogen and oxygen.

11. Mass in chemical reactions
A balanced chemical equation is like a recipe.
The mass of the products must equal the mass of the reactants.
Counting molecules is not practical so we usually need the mass of reactants and products of a chemical reaction.

12. Chemical Reactions
REMINDER: The law of conservation of mass states that in a chemical reaction matter is not created or destroyed but conserved.
This means that however many atoms you start with (reactants), you will end with the same amount of atoms (products)

13. Chemical Formula Reactants are the substances that chemically combine
yield
Reactants are the substances that chemically combine
Products are the new substances formed

14. Chemical Formula
Subscripts indicate the number of atoms needed for a compound.
Coefficients represent the number of units of each substance taking part in a reaction
2H2 (g) + O2 (g)  2H2O (l)
Coefficient
Subscript

15. WarmUp What is needed to start a reaction?
What does the law of conservation of mass state?
Was this law observed in your lab? Explain.

16. Review law of Conservation of mass
Watch this
Let’s talk about your lab
Watch this!
6/the-physics-of-popcorn.html

17. Let’s Practice Balancing!!

18. WarmUp
Create a visual representation of 3CO3 .(think about our bead lab)
Give the number of each atom present in the above compound.
Create a visual representation of 3Al(OH)3.
Agenda:
-WarmUp
-Review Hmwk
-Whiteboard practice
-Snowman Challenge

19. Counting Atoms
3NaOH
4CO2
2Fe2O3
5NaCl

20. Practice Balancing Reactions
Zn + HCl ---> ZnCl2 + H2
S8 + O2 ---> SO3
Sb O > Sb4O6

21. Practice Balancing Reactions
Zn + HCl ---> ZnCl2 + H2
S8 + O2 ---> SO3