Patterns of problems
6 min read

The P-Block Elements

- Get the best out of this chapter by practicing the kind of problems asked in various Exams!
1
Pattern-Anomalous behaviour of first member of p-Block Elements
Description: The anomalous behaviour of the first elements in p-block is generally due to their small size, large(charge/radius) ratio, high electronegativity, high ionisation enthalpy, and absence of d-orbital in the valence shell.
How to approach
Questions can be related to the factors that contribute to the unique behaviour in the first member of the p-Block elements and also the anomalies in their properties. To attempt such questions, it's good to brush up on the typical properties that Nitrogen, oxygen and fluorine display.
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2
Pattern-Oxidation state of p-Block Elements
Description: Oxidation state is also called the oxidation number - the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom. It could be positive, negative or zero.
How to approach
You can be asked to identify the oxidation state of element in a compound, the lowest or the maximum oxidation states that an element is known to display and stability of the oxidation states. We should have a fair idea of the common oxidation states of the p- block elements to solve questions related to it comfortably.
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3
Pattern- Ionisation Enthalpy and Electron Gain Enthalpy
Description: Ionization Enthalpy of an element is the amount of energy that an isolated gaseous atom requires to lose an electron in its ground state. Electron gain enthalpy of an element is the energy released when a neutral isolated gaseous atom accepts an extra electron to form the gaseous ion i.e. the anion.
How to approach
The questions can be asked related to the trends in ionisation enthalpy and electron gain enthalpy. You may also find questions asking you to compare the ionisation energy or electron gain enthalpy between different groups of the p-Block. If you understand the logic behind the trends in ionisation enthalpy and electron gain enthalpy, you are good to solve any related questions.
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4
Pattern-Thermal Stability, Reducing Power and Acid Strength of Hydrides
Description:All the elements of Group 15, 16 and 17 form hydrides of the type , and respectively. Thermal stability, reducing power and acid strength depends upon bond dissociation enthalpy of E-H ( or H-X in the case of group 17) bond. On moving down the group, as the size increases, bond dissociation enthalpy of E-H bond decreases - reducing thermal stability and increasing the reducing power and acid strength of the hydrides down the group.
(E = Elements of Group 15, and 16 and X = Elements of Group 17)
How to approach
The questions can be related to trends in thermal stability, reducing power and acid strength of the hydrides. To answer such questions easily, make sure to go through the trends in the acidic strength, thermal stability and reducing power of hydrides along the group.
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5
Pattern- Oxoacids of Nitrogen, Phosphorous and Halogens
Description: An oxoacid is an acid that contains oxygen. To be more specific, an oxoacid is an acid that contains oxygen and at least one hydroxy group.
How to approach
Mostly questions are based on strength of oxoacids and the structures. For that, we need to keep in mind that strength of oxoacids mainly depends on the number of oxygen atoms around the central atom and its electronegativity.
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6
Pattern- Interhalogen Compounds
Description: Two different halogens react to form inter halogen compounds.
How to approach
Questions are related to the structures of interhalogen compounds and chemical reactions. They can be solved easily by remembering the structures of interhalogens and their properties.
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