(b) Which has the larger sixth ionization energy, Se or Br?

Ionization energy is the energy required to remove an electron from a gaseous atom or ion. It is a key concept in understanding the reactivity and stability of elements. Generally, ionization energy increases across a period due to increasing nuclear charge and decreases down a group due to increased electron shielding.

Ionization energy exhibits specific trends in the periodic table. As you move from left to right across a period, ionization energy increases, while it decreases as you move down a group. This is due to the balance between nuclear attraction and electron shielding, which affects how tightly electrons are held by the nucleus.

When comparing elements like selenium (Se) and bromine (Br), it is essential to consider their positions in the periodic table. Bromine is to the right of selenium, indicating it has a higher nuclear charge and generally higher ionization energies. However, the sixth ionization energy specifically refers to the energy required to remove the sixth electron, which can be influenced by the electron configuration and stability of the resulting ion.