yes, for some reason the embryo/egg stops developing. It's not considered a 'clinical pregnancy'. Usually the hpt shows up positive, but that's about it. It won't become a fetus or anything.
A chemical pregnancy is when a woman's egg gets fertilized but the embryo doesn't make it. I think it has to be earlier than 5 weeks to be technically deemed a chemical pregnancy, so it may not have even shown up on a home pregnancy test yet. I've read that chemical pregnancies are likely freakishly common and that many, many women have probably experienced them and never even known it, because to them it was simply experienced as their period being a couple days late.