37. Solving a chemistry problem

3. By the serial number of the element, compose the electronic formula of its atom; determine the nature of the element and valence electrons; indicate the quantum numbers for the last three electrons; characterize the location in the Periodic table of D. I. Mendeleev; compare electronegativities, atomic radii, and ionization energies between an element and neighboring elements in a group and period; determine the composition of the atom (the number of electrons, protons and neutrons). No. of elements, 19, 75