Chemistry: 2.1 Significant Figures and Scientific Notation

These figures may not be significant to you, but they matter to us, okay? Oh, and to Science. They matter a ton to Science.

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ScienceChemistry

Transcript

00:23

figures lets us take a bit of a shortcut and only requires that we write down a [Man takes significant figure shortcut]

00:28

certain number of digits spending on a situation if we were performing a

00:32

calculation our answer is limited to the number of significant figures or sig [Girl using calculator]

00:38

figs as the cool kids column at reset in our unique precise number in other words

00:43

if we're multiplying 22.3 and 13.5 we're only going to include one two three sig

00:49

figs in our solution the other situation is when we're reading instrumentation in [Scientist reading instrument measurement]

00:54

which case the number of sig figs depends on the precision of the

00:58

instrument we're using the measure for now let's take a closer look at the

01:01

rules for calculation rule number one all nonzero digits are significant so if [Rule number one appears]

01:06

you've performed a calculation and your result is 114 write down 114 not 109 110

01:12

or no zeroes so smille rounding if you get a number that goes through the tens

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place like 114 point 8 you write one 14.8 in this case you'd have four [Hand points to 114.8 number]

01:22

significant figures rule number two zeros between nonzero

01:27

digits are significant so if you get 104 well you still got three significant [Person shows three fingers]

01:32

figures even though one of them is a zero but as long as you've got some form

01:36

of a zero sandwich it counts rule number three trailing zeros zeros to the right [Girl takes bite of zero sandwich]

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of a decimal point are significant so if your calculation comes out to one

01:46

hundred point zero degrees on the button you'd have four significant figures to

01:52

deal with all right finally rule number four leading zeros zeros to the left of

01:57

the first nonzero digits are not significant so say you come up with an [Boy appears with magnifying glass]

02:02

easy peazy number like 0.001 eight well one and the eight are significant the

02:10

zeros are not but we can't just write 18 correct

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that's not the same thing as 0.0018 oh how right you are scientific notation is

02:21

basically just a shorthand way of writing out troublesome numbers in a way [Man writing out numbers in notepad]

02:25

that's easy to understand and won't give us carpal tunnel trying to write it for

02:30

0.0018 you write the first non-zero number we come across the one and make

02:36

it 1.8 times 10 to the negative third because we'd have to move the decimal

02:42

point three places to the right in order to get our 1.8 number now if something [Decimal points moves to the right]

02:48

had a measurement of zero point zero zero zero zero zero zero 95 - yikes we'd

02:54

write it as nine point five two times ten to the negative seventh and so on we

03:00

can use the scientific notation for numbers greater than zero - but when we

03:03

do the exponent is always positive like five hundred would be five times 10

03:09

squared Y squared well because we'd have to move the [Decimal points moves two places to the left]

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decimal point two places to the left to get our five five hundred thousand would

03:18

be five times ten to the fifth and numbers greater than zero containing

03:23

decimals work to one thousand three hundred eighty eight point three would

03:27

be one point three eight eight three times ten to the third six point two

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would be six point two times ten to the zero power switch is just one so yet the

03:37

zero power thing is also what Superman has when wearing a kryptonite necklace [Superman sitting on sofa with kryptonite necklace]

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and that's it hopefully now you feel 1 times 10 squared percent smarter than

03:46

when we started