Chemblog!

Thanks to Emily for pointing out that Question 20 (thanks, Jenn!) had no answer choices. I updated the test file but here are the answer choices anyway:
(a) Na, Ar (b) Ar, As (c) As, Rb (d) Na, Rb

Also, on Question 24: there is a table of atomic radii in your reference tables. Read the text to see the three ways that atomic radii may be measured. Furthermore, the answer choices are given are in picometers AND they do not match the data in our reference tables so, here are the updated answer choices to that question:
(a) 1.04 A (b) 2.08 A (c) 2.54 A (d) 3.12 A

one A is 10 ^ -10 meters ( a tenth of a billionth of a meter )
one pm is 10 ^ -12 meters ( one trillionth of a meter )