polyatomic ions examples:
Question 3. What are polyatomic ions? Give examples.
In an ionic compound, entities either lose or gain an electron(s). When a group of atoms shares the transferred electron, we call such a group as a polyatomic ion. For example, in sulphuric acid (H2SO4); sulphite ion is (HSO4–). Here sulphite ion shares one electron between one hydrogen atom, a sulphur atom and 4 oxygen atoms. Thus it is a polyatomic ion.
How is it different from a typical ion?
In practical chemistry, polyatomic ion holds no special significance than typical ion. For the sake of definition purpose, a typical ion is an ion which shares the charge by a single atom. For example, in common salt (NaCl) Sodium loses an electron and forms a sodium ion while chlorine atom receives the electron and forms chloride ion. Here charge is shared by only one atom.
Examples of polyatomic ions:
Depending on the charge, it can be polyatomic cation or anion.
Polyatomic Cation: Ammonium ion (NH4+), Mercury(I) (Hg22+), Hydronium Ion (H3O+)
Polyatomic Anion: Nitrate ions (NO3–), Sulphate ions (SO42-), etc.
Next: Question 4. Write the chemical formulae of the following.
Ref: NCERT Science class 9 chapter 3.
polyatomic ions examples