1. Earth Chemistry
Chapter 04

2. Structure of Matter Elements Compounds Contain only one type of atom
Each type of atom is unique
Can’t be broken down
Compounds
Contains two or more elements
combined in a fixed ratio

3. Earth’s Crust The most abundant elements in the crust Oxygen- 45.67%
Silicon- 27.7%
Aluminum- 8.1%
Iron-5.0%

4. Atomic Structure Subatomic particles Proton- nucleus Neutrons- nucleus
Electrons- move around the electron cloud

5. Atom
Use the periodic table to determine the atomic number and mass number
The atomic number is equal to the number of protons in an atom, and it can also tell you the number of electrons in a neutral atom
To solve for the number of neutrons, you simply take: mass number- atomic number
To solve for the mass number, add protons and neutrons

6. Chemical Equations
Show what happens before and after a chemical reaction has occurred.
Reactants are the substances that undergo change.
Products are new substances that are formed as a result of the change.
Reactants Products

7. Chemical Equations
Representation of chemical reactions that shows the reactants and products as formulas
Notice that the number of atoms on the left side of the equation equal the number of atoms on the right side.
Example:
C + O2 CO2

8. Conservation of Mass
Antoine Lavoisier observed that the mass of the reactants in a chemical reaction always equals the mass of the products.

9. Chemical Bonds and Energy
The energy stored in the chemical bonds of a substance is called its chemical energy.
Chemical reactions involve the breaking of chemical bonds in the reactants and the formation of chemical bonds in the products.

10. Conservation of Energy
Exothermic- chemical energy of the reactants converts into chemical energy of products plus heat
Endothermic- chemical energy of the reactants plus heat converts into chemical energy of products
In both cases energy is conserved.

11. Chemical Bonds
Atoms that have less than full outer energy levels will seek to transfer or share electrons with other atoms.

12. Covalent Bond
Atoms that share electrons form a covalent bond

13. Ionic Bond
Results from the transfer of electrons

14. Reaction Rates
The reaction rate is the rate at which reactants change into products over time.
They tell how fast a reaction is going
(How fast the reactants are being consumed, how fast the products are being formed, or how fast energy is being absorbed or released)

15. Factors Affecting Reaction Rates
Factors that affect reaction rates include:
temperature, surface area, concentration, stirring, and catalysts

16. Temperature
If you are cooking an egg, the hotter the pan, the faster the egg cooks.
Increasing the temp typically causes the particles to move faster becoming more likely to react.

17. Temperature
Typically, an increase in temperature will increase the reaction rate
A decrease in temp will decrease the reaction rate.

18. Surface Area
An increase in surface area increases the exposure of reactants to one another.
The greater the exposure, the more collisions
The more collisions, the higher the likelihood of a substance reacting

19. Stirring
You can increase the exposure of reactants to one another by stirring them.
This increases the reaction rate.

20. Concentration
The higher the concentration of substances, the more particles are present in a given volume to react
There are more opportunities for collisions
Reaction rate is increased

21. Catalysts You can speed up reaction rates with catalysts.
Catalysts are substances that are not used up in reactions
They lower the amount of energy required to begin a reaction

22. Types of Reactions Synthesis reactions Decomposition reactions
Single-replacement reactions
Double-replacement reactions
Combustion reactions

23. Synthesis Reaction A+ B→ AB
Two or more substances react to form a single substance.

24. Decomposition Reaction
AB → A+ B
A compound breaks down into two or more simpler substances.

25. Single Replacement One element takes the place of another element.
A + BC → B + AC

26. Double Replacement AB + CD→ AD + CB
Two different compounds exchange positive ions and form two new compounds.

27. Oxidation/Reduction Reactions
One substance loses electrons and another substance gains electrons
Also called redox reactions

28. Combustion
A type of reaction in which a substance reacts rapidly with oxygen, often producing heat and light.
Sometimes classifications of chemical reactions can overlap.

29. Equilibrium
A state in which the forward and reverse paths of a change take place at the same rate.
Changes in matter can be either physical or chemical.

30. Equilibrium
Example: Water poured into a bottle and then sealed. Some water will evaporate while some water will condense. Eventually the rate of evaporation= the rate of condensation

31. Factors Affecting Chemical Equilibrium
Henri Le Chatelier in 1884 first introduced the principle that when a change is introduced to a system in equilibrium, the equilibrium shifts in the direction that relieves that change.

32. Factors Affecting Equilibrium
Temperature
Pressure
Concentration

33. The composition of a mixture is not fixed
Heterogeneous Mixtures have noticeably different parts

35. The substances are so evenly distributed that it is difficult to distinguish one substance from another.