Significant Digits and Scientific Notation

In our last Chem 11 class, we learnt about Significant Digits and Scientific Notation!

The concept of significant digits and scientific notation is pretty simple to grasp, so here are a few notes for you

A Significant Digit is a digit in a measurement that is certain, plus one digit that is an estimate

• Here's an example, there are three significant digits in the number 34.5. Two of which are certain, 3 and 4; and one which is estimated, 5.

When trying to tell how many digits are significant, remember when a zero is not significant. place holder zeroes in a measurement are not significant

• An example is 1040, how many significant digits are there? Well, to start off the 1 and the 0 are are exact and the 4 is an estimation. Therefore, there are only three significant digits. The final zero is a place holder zero and isn't significant.

When we add or subtract numbers, we determine the number of significant digits by depending on the number with the largest uncertianty

• Here's an example,  951.0 + 1407 + 23.911 + 158.18 = 2540., the decimal place is there to show that the final zero is not a place holder, but significant.

When we multiply or divide two numbers, we determine the number of significant digits by choosing the smallest number in the equation.

• An example is, 3.052 x 2.10 x 0.75 = 4.8, which means that there are two significant digits and we only use two digits because the smallest number of significant digits in the equation is 2.

Scientists have developed a shorter method of experssing large numbers, this method is called scientific notation, which is based on powers of the base number 10

The number 123, 000,000,000 is written as 1.23 x 10^11

Writing a number in scientific notation is easy!

Put the decimal after the first digit and drop the zeros. To find the exponent count the number of places from the decimal to the end of the number

So, in 123,000,000,000 there are 11 places after the decimal place which determines the exponent, which is 11.

That wasnt so hard, now was it?

Try out some examples to perfect your knowledge of Significant digits and Scientific Notation
Scientific Notation
6.34 x 10^5 =
4.89 x 10^-6 =
Significant Digits
0.0026701 =
19.0550 =

to end off the lesson, heres a mind boggling video on the relative size of things in the universe. (: