Question

Two elements A and B have atomic numbers 8 and 17 respectively. Identify their groups in the periodic table.

Answer 1

Can you do this by looking at a periodic table?
Each element will have two numbers: atomic number and mass number.
Atomic number is the smaller of the two.

Also, the group is just which column the element is in.
The columns are numbered a bit funny. They correspond to how many electrons are in the outer shell. You can basically ignore the transition metals for now.