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Course: AP®︎/College Chemistry > Unit 1

Lesson 6: Periodic trends

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Periodic trends

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You might need: Periodic table

The first two ionization energies for beryllium are shown below.

\begin{aligned} \begin{aligned} Be (g) & \to {Be}^{+} (g) + e^{-} \\ {Be}^{+} (g) & \to {Be}^{2 +} (g) + e^{-} \end{aligned} & \begin{aligned} I_{1} & = 900 kJ/mol \\ I_{2} & = 1757 kJ/mol \end{aligned} \end{aligned}

Which of the following identifies the most probable value for the third ionization energy for $Be$ ‍ and provides the best justification?

(Choice A)
$2672 kJ / mol$ ‍, because the electron removed during the third ionization is a core electron
(Choice B)
$2672 kJ / mol$ ‍, because the electron removed during the third ionization is a valence electron
(Choice C)
$14,849 kJ / mol$ ‍, because the electron removed during the third ionization is a core electron
(Choice D)
$14,849 kJ / mol$ ‍, because the electron removed during the third ionization is a valence electron

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