Periodic table/electron configuration/ion help

Question

Cation formed: Li +

Anion formed: P 3-

Formula of ionic compound formed?

Electron configurations of the elements?

Answer 1

Since Li forms a +1 ion and P forms a -3 ion they are in a 3:1 ratio

the formula of the compound is Li₃P

electron configuration of Li is 1s²2s¹

as an Li⁺ ion the electron configuration is 1s² because it loses its valence electron

electron configuration of P is 1s²2s²2p⁶3s²3p³

as a P^3- ion its electron configuration is 1s²2s²2p⁶3s²3p⁶ because it has gained 3 valence electrons