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chloe ko.
christina chow.
mr. doktor's chemistry class
block g

home. mrdoktor.

SIGNIFICANT DIGITS

• Today, we learned that accuracy and precision is VERY important in science so its important to communicatethis accuracy carefully.
• REMEMBER that calculators are not smart enough to decide that is precise and what is not, so you have to be the judge of that.
• Scientists have establish rules for rounding off extra digits so you MUST follow them!
• Non-zero digits are always significant
• If zero is a place keeper, it is generally NOT significant 

for example:
0.00027

• Any numbers to the left of a decimal point are significant.

examples:
143.0052
88.2010

• zeros after another number are significant.

example:
8.127       --------------4 significant digits
92.32135 --------------7 significant digits
0.0000150 -------------3 significant digits

• When adding or subtracting round to the least precise number.

examples:
9.1121-8.04 = 1.0721 ------------>1.07
2.4+83.2336=85.6336------------>86

• When you multiply or divide, round the number with the fewest significant digits.

examples:
4.11 x 0.0039 = 0.016029 ---------------------->0.0160
85.234 / 9.115608 = 9.350336258-------------->9.3503

• Constants (π, G, ect ) on your data sheet have infinite significant digits

SCIENTIFIC NOTATION

• Used if we need to write the number 3000 with only 2 SDs

example:
3.0 x 10^3 

• Used if we want to write the number 22 billion 5 hundred million without taking up an entire line 

example:
22,500,000,000      = 2.25 x 10 ^10

• Shows really big or really small numbers easily 

• Makes use of power of 10 

examples:
10^7 = 10,000,000
10^-7 =0.0000007


CALCULATORS

• Your calculator has funtions that you can use to do this easily 

• DON'T use the "^" sign on your calculator. It does not recognize the order of operations in all cases.