The document explains the concept of ions, defining them as charged species arising from the loss or gain of electrons. It details the characteristics of anions (negatively charged ions) and cations (positively charged ions), including their formation processes and energy dynamics involved. The document also notes the rarity of positive polyatomic ions compared to negative ones, providing examples of each type.

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2. ION & ITS
TYPES
An introduction
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ION;
‘Any specie carrying charge is called ion’
OR
“An atom or molecule with a net electric charge
due to the loss or gain of one or more electrons”
• It is charged because the number of electrons do not equal the number of protons in the atom or molecule.
P= +1
N= 0
Proton = electrons
Net charge = 0
Atom neutral
e e e e
e
e
e
• Electron gain
• e>p
• Net charge negative
• ANION
• Electron loss
• e<p
• Net charge positive
• CATION
ATOM

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Electrons = 10
Protons =9
Net charge = -1
Electrons = 9
Protons =9
Net charge =0
+++
+++
+++
+++
+++
+++
ANION
Ion which carry negative charge is called anion (negative ion).
• When atom of element picks 1 or more electrons it became anion
• A + e/es A
• Example; F + e F
• O +e O O + e O
THERMODYNAMICS OF ANION FORMATION
• Formation of uninegative ion is an exothermic process, while formation of dinegative ion is an endothermic
process.
−2

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CATION
Ion which carry positive charge is called as cation(positive ion).
• When an atom loses one or more electrons it form cation.
• B B + e
• Na Na + e
• Mg Mg + 2 e
• Formation of cation is an endothermic process as removal of electron needs energy.
• For removing second electron energy required is greater than first one.
• Similarly removal of 3rd is more difficult than 2nd one
• Most common positive ions are formed by metal atoms.
Electrons = 10
Protons =11
Net charge = +1 +++
+++
+++
Electrons = 11
Protons =11
Net charge = 0
+2

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❑ Negative ions containing group of atoms are common e.g. Carbonate ion ,chromate ion
❑ While positive ions containing group of atoms are rare. E.g. ammonium ion ,hydronium ion
EXERCISE
When uninegative ion is formed energy is released, tell the name of this energy?
When unipositive ion is formed energy is absorbed, tell the name of this energy?