Which of the atoms in guanine carry a partial negative charge (δ-) and which carry a partial positive charge (δ+?

There are two types of nitrogenous bases that form the DNA/RNA. These include the purines and pyrimidines.

Guanine is a derivative of purine and is made up of a fused pyrimidine-imidazole ring system with double bonds in conjugation. The molecular formula is C5H5N5O. Here, O being more electronegative than N will carry a partial negative charge while N will carry a partial positive charge.

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."

the atomic number will stay the same no matter how many electrons it has, so it doesn’t decrease nor increase. it’ll only change with a different number of protons