Judy,
I am no expert but, I usually scan all my chips between 100-150 dpi. It takes less file space and makes it easier if you are uploading to the Chip Board.
To check this yourself, scan a chip at 100dpi and then again at 300dpi, then right click it and look at properties. You'll see a big difference in file size but not that much difference in Pic quality. Just my opinion