Which of the following statements is true regarding ionization energy across a period?

Ionization energy refers to the amount of energy required to remove an electron from an atom in its gaseous state. As you move across a period on the periodic table, there are several important trends that occur, particularly in relation to atomic structure.

When we consider the statement about ionization energy increasing as nuclear charge increases, it is essential to understand what nuclear charge means. Nuclear charge is determined by the number of protons in the nucleus of an atom, which increases as you move from left to right across a period. As the nuclear charge increases, the attraction between the positively charged nucleus and the negatively charged electrons also increases. This stronger attraction makes it more difficult to remove an electron, hence requiring more energy to ionize the atom.

In summary, the correct statement reflects the direct relationship between increasing nuclear charge and increasing ionization energy as you move across a period in the periodic table.