How does group number tell you the aout of valence electrons?

Answer 1

The group number tells you how many valence electrons there are, except for transition metals, lanthanides, and actinides. So, for groups 1 and 2 , there are 1 and 2 valence electrons, respectively. Then it gets a little tricky. You skip to group 13, past the transition metals. What to do? You can't have 13 valence electrons. What you do is you use only the ones digit. Thus, metals in group 13 would have 3 valence electrons. The reason that the group number tells you the number of electrons is that that is the way that Dmitri Mendeleev ( the founder of the Periodic Table) set it up. Good Luck!