1. Warm up (9/13 and 14) 89010 20.0 3.210 x 1023 FIND YOUR NEW SEATS!
Yellow HW sheet (Sig Figs WS ) on desk please!
IN YOUR NOTES: How many sig figs are in the following numbers?
89010
20.0
3.210 x 1023
Write each of the above in scientific notation!
4, 4, 3, 4

2. Go over Homework

3. SIG FIGS: What are the Rules?
Nonzero integers always count as significant figures.
3456 has 4 sig figs
Leading zeros do not count as significant figures.
has 2 sig figs

4. SIG FIGS: What are the Rules?
“Trapped” zeros always count as significant figures.
16,007 has 5 sig figs
Trailing zeros are significant only if the number contains a decimal point.
9.300 has 4 sig figs
150 has 2 sig figs
150.0 has 4 sig figs
2 x 104 has 1 sig fig

5. Practice
Tell me how many sig figs are in the following numbers and write in scientific notation:
4.9008
3300
500
120.
6, 5, 2, 3, 1, 3

6. Scientific notation with Sig Figs
Use scientific notation to report the correct number of sig figs! It’s genius!
EXAMPLE:
To report 319,000 in scientific notation, is it:
x or x 105 ?
the three zeros are not significant, so they are not going to be reported in scientific notation

7. 9.749 9.7 Rounding If removing digits,
round up if digit is 5 or higher (1.37 = 1.4)
digit stays the same if less than 5 (1.33 = 1.3)
Only round based on the first number to the right
Round this number to 2 sig figs:
Try a few more! Round to 3 sig figs: ,
9.749
9.7
67.9; 156,000; OR 1.10 x 10 -3

8. Arithmetic with sig figs
Addition and subtraction
Report the smallest number of decimal places
12.10
+1.212
13.312
Multiplication and Division
Report the smallest number of total sig figs
2.35
X 11
25.85
Equals (2 decimal places)
equals 26 (2 sig figs)

9. Group Practice on Boards
On your whiteboards, show…
Calculator shows:
Correct answer:

10. Group Practice on Boards
140.7 – =
24.6 / = =
3450 x =
41.6, , 490.0, 3810

11. 7.98 x 413.0 / 67.19 = 4.93 + 140.1 x 53.709 = Challenge Problem! 49.1
7530. (follow both rules, but don’t forget PEMDAS!)

12. Finish Room Map?
1B and 2B

13. Safety Training Time
Please get out your syllabus with the Safety Contract, a pen or highlighter, and goggles!

14. Element Memory Quiz (10 min)
NO CHEATING OF ANY KIND!
Pack up so there is nothing on your desk – no pencil cases, etc. Just a pencil.
When you are done, flip it over so I can see you are finished!
I’ll trade you for a HW that you can start working on!

15. Homework Day 4 Read in your book: 68-71 (sig figs)
WS Day 4 (more sig fig practice) – do it on your own!
Make sure you are ready for:
LAB next class (shoes, lab books, etc)
Safety quiz T/W next week (must pass to participate in labs!)