Hi Raul, "job" is never used for the location of work. It is used for the position of work (or, less commonly, for an instance of work - a plumber goes to a house to do a job). We never say "I am going to my job". This is because, again, a job is something you do, not the place at which you do it. We almost always say "work" in this case. "I am at work". "I am going to work". You can't tell by looking at them, but actually, in these sentences, "work" is a *noun* referring to the location and activity - not a verb! "Work" is a place! You could say: "I am going to do some work at work" and it would be grammatically correct. but you will never hear it because it sounds so redundant :)

I am at my job = I am doing my job right now. I am at work = I am at my place of work. I am at a job = I am doing something right now. *I am at job = nonsense*

yes, "I'm at work" is preferred here. other possible variations could be: "I'm working." or "I'm busy doing my job." :)

Raul, You can say, I am at work......but you can't say.....I am at job....incorrect. You can say, I am at my work......or you can say.....I am at my (a) job. You can say, I am on the job.....but you can't say....I am on the work...incorrect. Certain combinations of words are considered collocations; they just sound "right" to native English speakers. On the other hand, other combinations just sound "wrong". There doesn't appear to be any reason for this; it's just the way the language developed over time. In addition, the collocations that I find acceptable as a Canadian may not be acceptable for English speakes in other countries.

"I am at work" is the best way to express being at a job.