Characteristics of various valent ions — lesson. Science State Board, Class 8.

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Monovalent, divalent, trivalent ions:

During a chemical reaction, an atom can gain or lose more than one electron. If the number of charges over an ion or radical is $1$, $2$, $3$, and $4$, it is monovalent, divalent, trivalent, and tetravalent, respectively.

The valencies of the ions can vary depending on the charges they carry.

Valency of anions (negative radicals) and cations (positive radicals):

An anion or cation's valency represents the number of hydrogen atoms or any other monovalent atoms ($Na$, $K$, $Cl$) that combine with them to give a suitable compound.

Example:

Two hydrogen atoms couple with one sulphate ion to form sulfuric acid.

The valency of sulphate ion is $2$.

2 H + {SO}_{4}^{2 -} \to H_{2} {SO}_{4}

One chlorine atom couple with one ammonium ion to form ammonium chloride.

{NH}_{4}^{+} + Cl \to {NH}_{4} Cl

The valency of ammonium ion is $1$.

Some anions' valencies:

Compound	Name of the anion	Formula	Valency
HCl	Chloride	$Cl^-$	$1$
$H_2SO_4$	Sulphate	${SO}_{4}^{2 -}$	$2$
$HNO_3$	Nitrate	${NO}_{3}^{-}$	$1$
$H_2CO_3$	Carbonate	${CO}_{3}^{2 -}$	$2$
$H_3PO_4$	Phosphate	${PO}_{4}^{3 -}$	$3$
$H_2O$	Oxide	$O^{2 -}$	$2$
$H_2S$	Sulphide	$S^{2 -}$	$2$
NaOH	Hydroxide	$OH^-$	$1$
$LaBO_3$	Borate	${BO}_{3}^{3 -}$	$3$

Some cations' valencies:

Compound	Name of the anion	Formula	Valency
NaCl	Sodium	$Na^+$	$1$
KCl	Potassium	$K^+$	$1$
$NH_4Cl$	Ammonium	${NH}_{4}^{+}$	$1$
$MgCl_2$	Magesium	${Mg}^{2 +}$	$2$
$CaCl_2$	Calcium	${Ca}^{2 +}$	$2$
$AlCl_3$	Aluminium	${Al}^{3 +}$	$3$
$FeCl_3$	Iron	${Fe}^{3 +}$	$3$

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7. Characteristics of various valent ions

Theory: