Page 86 - ICSE Chemistry 8

Table 4.6: Valency and Symbol of Some Common Ca ons
Valency Symbol Name

Monovalent Na + Sodium
(1) K + Potassium

Cu + Copper (I)/Cuprous
Ag + Silver (I)/Argentous
Hg + Mercury (I)/Mercurous
H + Hydrogen
NH 4 + Ammonium

Divalent Mg 2+ Magnesium
(2) Ca 2+ Calcium

Ba 2+ Barium
Zn 2+ Zinc
Ni 2+ Nickel

Cu 2+ Copper (II)/Cupric
Fe 2+ Iron (II)/Ferrous
Pb 2+ Lead (II)/Plumbous

Sn 2+ Tin (II)/Stannous
Ag 2+ Silver (II)/Argentite
Hg 2+ Mercury (II)/Mercuric
Mn 2+ Manganese (II)/Manganous
Trivalent Al 3+ Aluminium
(3) Fe 3+ Iron (III)/Ferric

Cr 3+ Chromium (III)

When an atom accepts electrons to acquire a stable electronic confi gura on, it becomes a nega vely
charged ion and is said to be an electronega ve ion.

During chemical reac ons, non-metals accept electrons resul ng in an excess of electrons over protons in
their atoms and become nega vely charged. This leads to the forma on of anions.

Examples of Formation of Electronegative Ions

–1
• Chlorine (Cl) accepts 1 electron to become chlorine ion (Cl ).

+1 electron
–
(17 electrons) Cl Cl (18 electrons)
Electronic confi gura on:

–
Cl 2(K), 8(L), 7(M) Cl 2(K), 8(L), 8(M)

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