The correct order of increasing acidic nature of SO2, SIO2, P2O3 and Al2O3 is-
The correct order of increasing acidic nature of SO2, SIO2, P2O3 and Al2O3 is-
The correct option is C Al2O3 < SiO2 < P2O3 < SO2
Acidity of oxides
The compounds formed from oxides and any other element is called an oxide. The oxides of metals are generally basic and those of non-metals are acidic. Therefore, across a period from left to right, there is a gradual increase in the acidity of the oxides. Oxygen (O) is an electronegative element.
The electronegativity of an element (the ability of attract shared pair of electrons) increases across a period due to the increase in the effective nuclear charge. As the electronegativity of the central metal increases, the electronegativity difference between the central element and Oxygen decreases and therefore, the basicity of the oxide decreases and acidity increase.
Therefore, across a period, the acidity of an oxide is directly proportional to is atomic number. The order of atomic number among the given elements is:
Aluminium (Al) < Silicon (Si) < Phophorus (P) < Sulphur (S).
Explanations for wrong answers
(A) Aluminium has the lowest atomic number among the given elements. Therefore, its oxide will have the least acidity. Option (A) is incorrect.
(B) Atomic number of Phophorus is less than that of Sulphur. Therefore, oxide of Phophorus will have lower acidity. Option (B) is incorrect.
(D) Oxides of Silicon and Sulphur will have higher acidity than Aluminium due to higher atomic number. Option (D) is incorrect.
Explanation for correct answer
(C) The acidity of the oxide is directly proportional to the electronegativity of the central metal which is in turn proportional to its atomic number across a period. Aluminium, Silicon, Phophorus and Sulphur belong to the third period and its order of atomic number is Aluminium (Al, Atomic number-13) < Silicon (Si, Atomic number-14) < Phophorus (P, Atomic number-15) < Sulphur (S, Atomic number-16). Therefore, the acidity of their oxides increases in the same order.
The correct option is (C) Al2O3 < SiO2 < P2O3 < SO2 .
Al2O3 < SiO2 < P2O3 < SO2
Acidity of oxides
The compounds formed from oxides and any other element is called an oxide. The oxides of metals are generally basic and those of non-metals are acidic. Therefore, across a period from left to right, there is a gradual increase in the acidity of the oxides. Oxygen (O) is an electronegative element.
The electronegativity of an element (the ability of attract shared pair of electrons) increases across a period due to the increase in the effective nuclear charge. As the electronegativity of the central metal increases, the electronegativity difference between the central element and Oxygen decreases and therefore, the basicity of the oxide decreases and acidity increase.
Therefore, across a period, the acidity of an oxide is directly proportional to is atomic number. The order of atomic number among the given elements is:
Aluminium (Al) < Silicon (Si) < Phophorus (P) < Sulphur (S).
Explanations for wrong answers
(A) Aluminium has the lowest atomic number among the given elements. Therefore, its oxide will have the least acidity. Option (A) is incorrect.
(B) Atomic number of Phophorus is less than that of Sulphur. Therefore, oxide of Phophorus will have lower acidity. Option (B) is incorrect.
(D) Oxides of Silicon and Sulphur will have higher acidity than Aluminium due to higher atomic number. Option (D) is incorrect.
Explanation for correct answer
(C) The acidity of the oxide is directly proportional to the electronegativity of the central metal which is in turn proportional to its atomic number across a period. Aluminium, Silicon, Phophorus and Sulphur belong to the third period and its order of atomic number is Aluminium (Al, Atomic number-13) < Silicon (Si, Atomic number-14) < Phophorus (P, Atomic number-15) < Sulphur (S, Atomic number-16). Therefore, the acidity of their oxides increases in the same order.
The correct option is (C) Al2O3 < SiO2 < P2O3 < SO2 .
