Question

the seventh periods is the ______ period but it is _________​

Answer 1

7th period is considered incomplete because it consists of elements which have not been studied properly yet. Their properties may change after getting sufficient information about them. Thus, we can't give them a permanent recognition as all the elements in the periodic table have many properties and similarities to follow. We've just assigned name to them. Moreover, most of them have been artificially synthesized in the laboratory and are not naturally occurring elements. Not only this, they are also highly unstable elements and not much information is available on them.