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## AP®︎/College Chemistry

### Unit 1: Lesson 7

Valence electrons and ionic compounds

# Valence electrons and ionic compounds

AP.Chem: SAP‑2 (EU), SAP‑2.B (LO), SAP‑2.B.2 (EK), SAP‑2.B.3 (EK)
You might need: Periodic table

## Problem

The first four ionization energies for element X are shown below.
Ionization energy (k, J, slash, m, o, l)
First738
Second1451
Third7733
Fourth10543
Based on the information in the table, which of the following is the most likely empirical formula of the ionic compound that forms between element X and oxygen?