Calculate the number of electrons, protons and neutrons in the following species:
`(i) `_(15)^(31)P (ii) `_(15)^(31)P^(3-)`

Answer

(i) `_(15)^(31)P`
`{:("Number of electrons",=,"Atomic number"=15),("Number of protons",=,"Atomic number"=15),("Number of neutrons",=,"Mass number -Atomic number"`=31-15=16`):}`
(ii) `_(15)^(31)P^(3-)`
`P^(3-)=P+3e^(-)`
Thus, phosphide ion contains same number of protons an neutrons but contains three electrons more than phosphorus atom.
number of electrons `=15+3=18`
Number of protons `=15`
Number of neutrons `=31-15=16`