How might the atomic numbers of elements indicate that newly discovered elements would have to have very high atomic numbers?

i just learnt this recently but i need to look through my notes again

the dissociation of nickel hydroxide is follows:

the concentration of hydroxide ion is

the equilibrium constant value of nickel hydroxide is = 6.1 * 10^-^1^6 and thus equilibrium equation can be written as:

thus, concentration of ni is 0.23 * 10^-^4 mol /l