[keuscho20]

Hi, I am having trouble with differences in attractiveness and repulsiveness with the following figure representing the potential energy surface of a phosphorylation reaction.
 
The exercise asks me to briefly explain the attractive and/or repulsive character of the PES at the stage(s) involved.

R means reactives.
TS1-1 means first transition state.
I0 means Intermediate.
TS1-2 means second transition state.
I means products.

[Corribus]

I'm not 100% certain what you mean by attractiveness and repulsiveness of the surface. Do you have the exact language used by the question?

Were I to hazard a guess, it'd be that "attractiveness" means tendency toward a certain point and "repulsiveness" means tendency away from a certain point. If that's what the question refers to, then attractiveness and repulsiveness at one point (A) relative to another (B) would be indicated by the mathematical gradient (i.e., slope) at (A) along the vector defined by the two points (B) in the direction of (A). If the slope = positive, attractive (reaction moves toward (B)); if the slope = negative, repulsive (reaction moves toward (A)). This basically has the meaning that if (A) has lower potential energy than (B), then the reaction at (A) moves away from (B). If (A) has higher potential energy than (B), then the reaction at (A) moves toward (B).