[Sabrina123]

How do we find the most metallic atom and central atom?

Metallic properties decrease as you move across a period and increase as you move down a group


I have tried most of these so can you tell me if I am right or wrong...
hyperchlorite ClO(−): Cl is the central atom
H3O(+): H
SbF4(−): Sb
XeF2: Xe
COF2- ?
SO3(2-): O

[JGK]

With hypochlorite (ClO-0^-) doesn't really have a central atom as there are only 2 atoms present.

As for your other answers :

H₃O⁺: H     Incorrect
SbF₄⁻: Sb  Correct
XeF₂: Xe      Correct
COF-₂^- ?
SO₃^2-: O   Incorrect

Generally, the atom with the higher valency will form the centre of the molecule.