# Why does Pb have a higher electronegativity than Sn?

I recently learnt that electronegativity generally decreases as I move down a group and from right to left within a period. However, according to the table below, Pb has an electronegativity of $$2.33$$, which is higher than $$1.96$$ of Sn. There are also a lot other elements, such as Au, Hg, and W, that does not follow the general rule of electronegativity.

Can someone offer an explanation of why some elements have a higher electronegativity than the elements directly above them?

• Elements in Period 6 get f orbitals for the first time. 4f subshell has relatively poor shielding effects, thus it's harder for the atoms to lose the outer electrons, increasing electronegativity. (similar reasons also account for some chemical properties of Period 4 elements, like $$\ce{H2SeO4}$$'s oxidizability)