1. ionization energy is the energy needed to remove an electron from an atom. we can use the periodic table to predict ionization energy for an element. • state and explain the trend for ionization energy as you move from left to right across a period. • state and explain the trend for ionization energy as you move down a group. (5 points) 2. a neutral atom of phosphorus has 15 electrons. explain why the electron configuration below is not the correct configuration for a neutral atom of phosphorus in its ground state. 1s2 2s2 2p6 3s2 3p2 4s1 3. find rubidium, magnesium, and aluminum on the periodic table. fill in the table below based on the locations of these metals on the periodic table. be thorough in filling in the far right column! left to right column: element symbol group number number of valence electrons general reactivity of the metal with an explanation for this reactivity based on the number of valence electrons up to down column: rubidium magnesium aluminum