Iodine electron configuration is:
1S^2 2S^2 2P^6 3S^2 3P^6 4S^2 3d^10 4P^6 5S^2 4d^10 5P^5
when Krypton is the noble gas in the row above iodine in the periodic table,
we can change 1S^2 2S^2 2P^6 3S^2 3P^6 4S^2 3d^10 4P^6 by the symbol
[Kr] of Krypton.
So we can write the electron configuration of Iodine:
[Kr] 5S^2 4d^10 5P^5
PH=14-pOH
pOH=-lg[OH⁻]
pH=14+lg[OH⁻]
pH=14+lg(8.7*10⁻¹²)=14-11.06=2,94
Adding the number of protons by the number of neutrons
