1. Find the average of the following numbers…
17, 18, 17, 17, 18, 17, 17, 17, 17, 18, 19, 17, 19, 17, 17, 18, 17, 19, 18, 17, 17, 17, 18, 19, 18, 19, 17, 17, 19, 18, 18, 17

2. What trick did you find? 17 x 17 = 289 18 x 9 =162 19 x 6 = 114
= 565
There are 32 numbers being added together
The average of these numbers is 565/32 =

3. Average atomic mass is dependent upon the abundance of each isotope
Why is the average atomic mass different from the average of the isotopes?
18 is not
Average atomic mass is dependent upon the abundance of each isotope

4. What is an isotope? An atom with a different number of neutrons
Different isotopes of an element all of the same number of protons