My period is due in one week and i did a pregnancy test today and its negative... is there a chance i could get pregnant in one week?

Possible: It is possible to get pregnant in that time period but there is no way to guarantee a specific time period for conception. It is highly varialbe from patient to patient.

Yes : If your cycle is due in one week, then you probably ovulates a week ago. If you had unprotected intercourse then a preg test may be negative now (because its too early). However it may be positive a week later.