Physics work function v ionization energy

[Min3rva]

Could anyone explain why work function is less than the ionization energy please ?
Many thanks

www.physics.com.sg/A14QuantumPhysicsLineSpectra.htm

effectively the energy measured in the work function is not the energy for complete ionisation so it takes less energy.

That's just what I was going to say not

@species5618 effectively when considering the work function, the electron could be regarded as having already "done" some of the work of ionisation as it exists in the sea of free electrons on the surface of the metal, whereas the theoretical electron being considered in an ionisation calculation is occupying an orbital shell of the atom and is therefore more "strongly held" in that place.

I trust that is now totally clear?

what I would love to know is why OP thought this was the best place to ask given that the info is readily available from a quick Google.

That's cleared it up nicely. A quick google shows that's "only" A Level and to be honest, I can't even pronounce your user name.

Thankyou. I did Google but couldn't equate this idea of ground state orbitals with metallic bonding .
But I will persevere .

perseverance is good. keep at it, it's all good fun and a wonderful feeling of enlightenment when a complex idea "clicks" for you.