What are poly-atomic ions?
Answers
Polyatomic ions are electrically charged collections of two or more atoms.
Polyatomic ions usually have a charge because the collection of atoms has either gained an extra electron or else it has lost an electron.
Most common inorganic polyatomic ions have negative charges. This means the ion more electrons than neural atoms which are in the ion. A polyatomic ion like phosphate, , has three extra electrons beyond the electrons on P and O atoms. Extra electrons are shared by all atoms in the polyatomic ion. These electrons are smeared around atoms in the ion.
If one counts the valence electrons in phosphate ion, one will see that there are 32 electrons. Neutral P and O atoms originally had only 29 valence electrons. Negative charge is due to extra three electrons which came from some outside source like metal atoms that formed cations. The charge is written outside brackets to indicate that charge is spread on the ion as a whole.
Single most common positive polyatomic ion is ammonium ion . Positive polyatomic ions are short electrons. Polyatomic ions are short electrons and have a ‘central’ atom. The central atom is physically in the middle of the ion. Other atoms are attached to central atom. Normally, oxygen atoms are attached to central atom and radiate out like spokes. Hydrogens are attached to the oxygens. Hydrogens are ‘terminal’ atoms far from the central atom. Oxygens act as a bridge between central atoms and the hydrogens as in and (phosphoric acid and phosphorous acid).