2. Write symbols of the following elements and the radicals obtained
from them, and indicate the charge
on the radicals.
Mercury, potassium, nitrogen, copper,
sulphur, carbon, chlorine, oxygen

The symbol of the Element is simply just the abbreviation.  

Mercury: Hg  

Potassium: K  

Nitrogen: N  

Copper: Cu  

Sulphur: S  

Carbon: C  

Chlorine: Cl  

Oxygen: O  

The number of unpaired valence electrons determine the radical in any element.  

Mercury: Hg 2+  

Potassium: K+  

Nitrogen: N 2+  

Copper: Cu 2+  

Sulphur: S 2-  

Carbon: C 4+  

Chlorine: Cl -  

Oxygen: O 2-  

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