1. Turn in Homework Journal: Warm Up
1. Explain the difference between a physical and chemical change.
2. Explain the difference between homogenous and heterogeneous mixtures.
3. What are 3 ways that a mixture can be separated?

2. 2.2 & 2.3 & 2.4 Notes

3. Element vs. Compound 2 or more elements combined
Simplest form of matter
Can NOT be separated into simpler substances by chemical means
Building blocks of other substances
Examples: oxygen, hydrogen, etc
2 or more elements combined
Substance that can be separated into simpler substances by chemical means
H2O

4. Properties of compounds compared to the elements
Sugar, C6H12O6: sweet, white, edible
Carbon, C: black, tasteless solid
Other interesting examples
Salt, NaCl
2 Na Cl = 2 NaCl

5. Symbols and Formulas
Chemical Symbol: a one or two letter symbol for the name of an element
Journal #1: Element symbols that you must memorize the name!!!!
C H He N O P S
Na Mg K Ca Cl F Al
Fe Cu Ag Au Hg Pb Sn

6. Chemical Reactions: Chemical Change
Changing reactants to products
Reactants: starting substances
Products: substances that are formed
Equation example
Reactants  Products
H2 + I2  2 HI(g)

7. Journal #2: Write down the following chemical reaction
NH4NO3  N2 + O2 + H2O
Label the reactants and products

8. Conservation of Mass Mass is neither created nor destroyed
Total mass of reactants = total mass of products

9. Journal # 3
NH4NO3  N2 + O2 + H2O
When 20 grams of ammonium nitrate (NH4NO3) break down, 7 grams nitrogen (N2) and 4 grams of oxygen (O2) form.
How many grams of water are formed?

10. Journal # 3 Answer NH4NO3  N2 + O2 + H2O 20 grams = 7 g + 4 g + X g
When of ammonium nitrate (NH4NO3) break down, 7 grams nitrogen and 4 grams of oxygen form. How many grams of water are formed?
X = = 9

11. During any chemical reaction, the amount of matter is unchanged!!!
Mass is neither created nor destroyed
Matter is neither created nor destroyed

12. 3.1 The Importance of Measurement

13. Scientific Notation Mathematical abbreviation for measured values
Coefficient x 10n
The coefficient is greater than or equal to one and less that 10.
Example:
67,500,000,000,000.0
Decimal moves 13 places to the left
6.75 x 1013

14. Example:
Decimal moves 6 places to the right
4.89x10-6

15. Journal #4 Now its your turn!!!!
Convert the following values into scientific notation:
63100

16. Journal #4 Now its your turn!!!!
Convert the following values into scientific notation:
= 8.67 x 107
= 5.2 x 10-7
63100 = 6.31 x 104

17. Accuracy
Measure of how close a measurement comes to to the actual or true value of whatever is measured

18. Precision
Measure of how close a series of measurement are to one another
Depends on more than one measurement!

19. Error accepted value Error = accepted value - experimental value
Percent error = ___|error | ___ x 100
accepted value

20. Journal #5 accepted value Error = accepted value - experimental value
Percent error = ___|error | ___ x 100 %
accepted value
You measured the diameter of a ball to be m. The package states that the ball has a diameter of 0.5 m. Identify the error and percent error of your measurement.

21. You measured the diameter of a ball to be 0. 489 m
You measured the diameter of a ball to be m. The package states that the ball has a diameter of 0.5 m
Error: = 0.011
Percent error = x 100 = 2.2 %
0.5

22. Significant Figures How do we round in Chemistry???
Significant Figures give the reader an idea of how well you could actually measure/report your data.
Rules for significant figures:
1) ALL non-zero numbers (1,2,3,4,5,6,7,8,9) are ALWAYS significant.
2) ALL zeroes between non-zero numbers are ALWAYS significant.
3) ALL zeroes which are SIMULTANEOUSLY to the right of the decimal point AND at the end of the number are ALWAYS significant. (2.400)
4) ALL zeroes which are to the left of a written decimal point and are in a number >= 10 are ALWAYS significant. (300.0)

23. How Many sig figs? 49,582 has __ sig figs 3.967 has __ sig figs
Rules for significant figures:
1) ALL non-zero numbers (1,2,3,4,5,6,7,8,9) are ALWAYS significant.
2) ALL zeroes between non-zero numbers are ALWAYS significant.
3) ALL zeroes which are SIMULTANEOUSLY to the right of the decimal point AND at the end of the number are ALWAYS significant. (2.400)
4) ALL zeroes which are to the left of a written decimal point and are in a number >= 10 are ALWAYS significant. (300.0)
49,582 has __ sig figs
3.967 has __ sig figs
9.006 has __ sig figs
has __ sig fig
has __ sig figs
has __ sig figs
3,000,000 has __ sig fig
10.0 has __ sig figs

24. How Many sig figs? 49,582 has 5 sig figs 3.967 has 4 sig figs

25. Using rounding in calculations
Addition/Subtraction: The answer to an addition or subtraction problem should be rounded to the same number of decimal places as the measurement with the least number of decimal places.
Example: =
needs to be rounded to 902.2

26. Multiplication/Division: answer needs to be rounded to the same number of significant figures as the measurement with the least number of significant figures
Example: 200 x = 915.8
needs to be rounded to contain only 1 significant figure so your answer is 900

27. The End