Why are all members of the same family on the periodic table likely to react in the same way and with the same elements?
It just is.
Each element has a shells. One way that they are alike and has the same properties is because they have the same needs to fulfill their complete shell.
Just like elements in the 7th family. They all desperately need that one extra element to feel satisfied.
Just like elements in the 1st family desperately need to get rid of that single electron to complete their shell.