Changing Major Junior Year

This year I will be a junior transfer student at Macalester College. I applied as a psych major (and wrote my essays about psych). However, I have been taking chem courses each semester since freshman year and I would like to change my major to chem. Would the college be frustrated by this?

No- that’s part of the point of a LAC! But: you should do some homework before you go to your advisor, looking at how you will finish the major in 2 years. Go in with a plan, even if the plan needs some adjusting/finalizing.