The first ionization energies of five consecutive elements in the periodic table with atomic numbers Z, Z+1, Z+2, Z+3 and Z+4 are given below. Z is less than 16 and one of these elements is a metal. The ionization energy values are not given in any particular order. Ionization Energies: Energies: 495, 1313, 1681, 2081, 1402 kJ mol-¹
