In changing ATP to ADP more energy is released when the new bonds form than needed to break off the phosphate group. What type of reaction is this?

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

it is stable as it is in group 0 which have full outer shells of electrons