 Antimony is in the nitrogen group ( group 15 ) and has an <unk> of 2 @.@ 05 . As expected from periodic trends , it is more electronegative than tin or <unk> , and less electronegative than <unk> or arsenic . Antimony is stable in air at room temperature , but reacts with oxygen if heated , to form antimony trioxide , <unk> . 
