More neutrons in the nucleus More electrons in the outer energy level The size of the atom increases - e-eduanswers.com Answers: 1 See answers Another question on Science. ... which leads to a decrease in the ionization energy as one moves down a group. Ionization energy is the energy required to remove an electron from a specific atom. Outermost electrons are far away from the nucleus and thus can be removed easily. It would take more energy to remove a electron. So, the outer electrons "experience" a reduced nuclear charge holding them onto the atom. Hi.. I dont understand why.. so confused.. Ok so.. why the Ionization of CL is less than that of F.. Ionization energy is the energy required to remove an electron from a neutral atom. The ionization energies associated with some elements are described in the Table 1.For any given atom, the outermost valence electrons will have lower ionization energies than the inner-shell kernel electrons. Science, 28.10.2019 15:29. 1 ... Ionization energy = the amount of energy it takes for an atom to lose an electron Remember that the nucleus is positively charged and the electrons are negatively charged. Let us understand why does ionization energy decrease from top to bottom in a group. Please I need help.. Figure \(\PageIndex{1}\) graphs the relationship between the first ionization energy and the atomic number of several elements. Based on your graph what is the distance with the highest probability of finding dot? While moving down in a group, the atomic number increases and the number of shells also increases. Down a group, the IE 1 value generally decreases with increasing Z. I don't understand.. I thought if the Ion has a third energy level like CL. While moving down in a group inside the periodic table, the nuclear charge increases, while the atomic also increases. Correct answer to the question Why does the ionization energy decrease as you move down a group on the periodic table? The regular decrease in going down the group is … As you go down a group, the outer electrons are farther and farther away from the nucleus, and are "shielded" from the nuclear charge by more electrons in the inner shells. Within a period, the values of first ionization energy for the elements (IE 1) generally increases with increasing Z. It is measured in kJ/mol, which is an energy unit, much like calories. Ionization energy increase across a period and decreases down a group, therefore the the element with the greater ionization energy would be found in the top right of the periodic table. 2. Why does ionization energy decrease down groups on the periodic table Elements from CHEMISTRY 1 at Hillsborough Community College As we all know that the value of the ionization energy decreases as regularly with increase in atomic number in going down the group. Why does ionization energy decrease down a group? This is because the principal quantum number of the outermost electron increases moving down a group. Why does ionization energy decrease as the number of main energy level increases?? The second factor that decreases the ionization energy is the shielding effect due to an increasing number of shells as we move down a group. Ionization decreases moving top to bottom down an element group (column).