Significant Figure Notes

With scientific notation too

Sig Figs

• Rule 1: “Non-Zeroes Count”NON-ZERO numbers ARE significant

How many sig figs? 3.1428 ____3.14 ____ 469 ____

Sig Figs

• Rule 2: “Sandwiched Zeroes Count”All zeros BETWEEN significant digits ARE significant.

How many sig figs? 7.053 x 103 ____ 70501 ____ 3020 ____

Only count the numbers to the left of the multiplication sign!

Sig Figs

• Rule 3: “Lefty Zeroes Don’t Count”Zeroes to the LEFT of significant figures are NOT significant.

How many sig figs? 0.0056 ____ 0.07089 ____ 0.000001 ____

Sig Figs• Rule 4: “Righty Zeroes…Sometimes Count”

• Zeroes on the far right ARE significant if the number contains a DECIMAL POINT

• Zeroes on the far right are NOT significant if the number has NO decimal point

How many sig figs? 4.300 x 10-4 ____ 200 ____ 0.010050 ____ 78020 ____

PracticeWe Do:

3.705 mL _____0.0052 g _____82,000 s _____6.19 x 101 years ______

Next, try the “You Do” problems on your own!!

Scientific Notation

I Do: 3250000000 0.00034

Scientific Notation

I Do: 3250000000 0.00034

We Do: 0.025 55, 000

Now try the “You Do” problems on your own!

Scientific Notation IN REVERSE!Make sure you know how to go in both

directions!

4.78 x 10-2 5.50 x 104 This can also be done with a calculator!

Addition/SubtractionWhen you add or subtract numbers with

different precision, you must round your final answer to the least precise number place.

Ex. 150.0 g + 0.507 g 150.507 150.5 g

Addition/SubtractionWhen you add or subtract numbers with different

precision, you must round your final answer to the least precise number place.

We Do: What is the total mass of 33.0 g of KCl and 56.50 g of H2O2?

Now try the “You Do!”

Multiplication/DivisionWhen you multiply or divide numbers with different

precision, you must round your final answer to the least number of sig figs.

We Do: What is the density (D = m/V) of a 87.45 g metal sample with a volume of 2.0 cm3?

Now try the “You Do!”