Question

How does the ionization energy vary across the Period?

Answer 1

You are saying that ionization energy increases across a Period, from left to right as we face the Table?

Explanation:

We examine the following reaction:

`M(g) + Delta rarr M^(+)(g) + e^-`

Going across the Period from left to right (facing the Table) the nuclear charge increases progressively with `Z`, the atomic number. Incomplete electronic shells shield the nuclear charge VERY imperfectly, with the result that ionization energy goes up substantially across the Period, and reaches a maximum at the end of the Period, at the Noble Gas.

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