Why does liquid diatomic Bromine have a net charge of zero when Bromine itself has a net charge of +/-1,5.

Why does liquid diatomic Bromine have a net charge of zero when Bromine itself has a net charge of +/-1,5.
Diatomic bromine is two neutral bromine atoms stuck together with a covalent bond. I'm not sure what you mean about it having a net charge of "+/-1,5". The bromide anion usually has a chare of -1, when it exists as an ion. In Br2 it's not an ion.

Why is it not an ion in Br2? Why shouldn't the charge be -2 in Br 2? Thats where I'm confused. Thanks

Why is it not an ion in Br2?
Because it just isn't. Most elements are stable in more than one oxidation state. Br can exist as Br- or just neutral Br. In Br2, it's two neutral Br atoms stuck together.

Or, if you want a more complicated explanation, any additional electrons that you added to a neutral Br2 molecule would be going into an antibonding molecular orbital, which would raise the energy of the molecule and destabilize it.

tnx

Is diatomic bromine / chlorine/ flourine bonded covalently? I would suppose it's a mutual -1 oxidation state where each atom has a 6-8 valence electron "count."

oops!

Is diatomic bromine / chlorine/ flourine bonded covalently? I would suppose it's a mutual -1 oxidation state where each atom has a 6-8 valence electron "count."
If they were both -1, it would have a -2 charge.

Because it just isn't. Most elements are stable in more than one oxidation state. Br can exist as Br- or just neutral Br. In Br2, it's two neutral Br atoms stuck together.

Or, if you want a more complicated explanation, any additional electrons that you added to a neutral Br2 molecule would be going into an antibonding molecular orbital, which would raise the energy of the molecule and destabilize it. So basically electrons are added to break bonds in the case of Br2, but is this always the case? Can you add an electron to break an O2 molecule? or an Hg2 bonds? My guess is that it depends on the availability of antibonding orbits but could you explain?

So basically electrons are added to break bonds in the case of Br2, but is this always the case? Can you add an electron to break an O2 molecule? or an Hg2 bonds? My guess is that it depends on the availability of antibonding orbits but could you explain?
Yes, adding an electron would weaken the bonds in Br2 or O2 because any added electrons would go into antibonding orbitals. It just depends on whether the lowest-energy molecular orbital that has room for electrons is bonding or antibonding. The lowest molecular orbitals in Br2 and O2 that have room for more electrons are antibonding orbitals, so adding more electrons would weaken their bonds. A CN molecule, on the other hand, has an empty spot in a bonding orbital, so adding another electron to make CN- actually strengthens the carbon-nitrogen bond.