Question

explain " middle row anomaly"

Answer 1

as the third row is almost the " middle row" of the periodic table, the word, middle row anomaly comes into effect. Hope this information will clear your doubts regarding the topic.

Answer 2

Middle row anomaly is observed in halogen group Br doesn't show +5 and +7 oxidation states. 3d orbital has no radial node and hence is very close to the nucleus whereas 4p has 2 radial nodes and hence the transition of electrons between these is not very likely and hence Br doesn't show these oxidation states and this is known as middle row anomaly. Other elements of 3rd period also show this phenomenon.