Periodic table/electron configuration/ion help

Question

Cation formed: K+

Anion formed: O-

The electron configurations?

Formula of ionic compound formed?

Answer 1

Hello Kim!

The atomic number of potassium is 19, so the electron configuration is:

K: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹

The electron configuration of K⁺ is the same, minus the outer electron:

K⁺: 1s² 2s² 2p⁶ 3s² 3p⁶

The atomic number of oxygen is 8, so the electron configuration is:

O: 1s² 2s² 2p⁴

For the O^-, we must add one electron:

O^-: 1s² 2s² 2p⁵

O^2-: 1s² 2s² 2p⁶

The compound formed is K₂O