I have an exam in about an hour and I thought I got it, but my study group just totally confused me because two of our members are lost. I just want to make sure I'm understanding this. In an SN1 reaction, there are two products. You substitute one, then you switch two groups and that's because it's a 2-step process? In an SN2 reaction, it's a 1-step process and there's only one product so you do the substitution and switch two groups simultaneously and end up with only one product. Is that right or do I have it totally wrong? Please help.