Question

1. what do the elements in each group have in common 2. what do the elememts in each period (row) have in common?

Answer 1

I'll assume you are referring to the periodic table

1. The elements in each group have the same number of electrons in the outer orbital.

2. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor.