Cation/anion formation from neutral atom

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Chemical Specie (Ion):

Ion is one of the among chemical species like atoms, molecules, free radical, and molecular ions.

 Ions are charged particles, containing either positive charge or negative charge. Positive charge ion is known as Cation and Negative ion is known as Anion.

Cations ( Positive ions):
 These are formed when an atom (neutral particle) release one or more electrons from its outer most and get positive charge like Na+, Mg+2, Al+3 etc.

Sodium ion Na+ formation( A cation): 


Sodium(Na) is an atom being atom it is neutral. Its atomic number is 11, it contains 11 protons in its nucleus and 11 electrons in its shells. Its valence shell (outer most shell which determine valency) has one electron as shown in the figure. To get stable by octet rule it loses  its one electron from its valence shell and get configuration of nearest nobel gas i.e neon(Ne) as shown in figure

Sodium ion formation


How does cation get positive charge?

Like sodium atom is neutral because
No of protons= +11
No of electrons=-11
Net charge=0

While in sodium ion
No of protons=+11
No of electrons=-10
Net charge= +1
Chloride ion(Cl- ion) formation( An anion):
Chloride (Cl ) is an atom and neutral . its atomic number is 17 means it contains 17 protons in its nucleus and 17 electrons in its shells.its valence shell has seven electrons as shown in figure , to get stable by octet rule it gains one electron and gets configuration of nearest nobel gas i.e argon(Ar).as shown in figure


Chloride ion formation

How does anion get negative charge?
Chlorine is neutral because :
No.of protons=+ 17
No. Of electrons=- 17
Net charge= 0
While chloride is charged because:
No. Of protons=+17
No.of electrons=-18
Net charge=0


Note: Here, one thing to remember name of cation doesn't change after becoming ion :

 Sodium atom becomes sodium ion(Na+)
Calcium atom becomes calcium ion(Ca+2)
Aluminum atom becomes Aluminum ion(Al+3)
while, anion name takes "ide" at end like;
chlorine atom becomes chloride (Cl-)
oxygen atom becomes oxide(O-2)
nitrogen atom becomes nitride(N-3)

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