I am reviewing my test and I having trouble figuring out the answer to the following question:

List the following element symbols in order of decreasing exothermic electron affinity: Al, Ca, As

_______>________>________

I wrote: Al>As>Ca (I got it wrong)
I know that if it is favorable to pick up an electron, energy will be released yet, I am still confused about what is the correct answer. Thank you!

2 answers

As is the right most element in the periodic table (of the three elements); I would pick that as the highest.
Ca is the left most element in the table; I would pick that as the lowest. Al must be between. You can look up the electron affinities at www.webelements.com
Thank you, I guess I got confused with Al and As :)