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Classification of Elements and Periodicity in Properties
Periodicity of Valence or Oxidation State
Example: Consider the two oxygen- containing compounds: OF2 and Na2O
The oxidation state of an element in a particular compound is the charge acquired by its atom on the basis of electronegative consideration from other atoms in the molecule.
Anomalous Properties of Second Period Elements
The first element of each of the Group 1 (lithium), Group 2 (beryllium) and Groups 13–17 (boron to fluorine) differs from the other members of their respective groups. Example: Lithium unlike other alkali metals and beryllium unlike other alkaline earth metals form compounds with pronounced covalent character.
The behaviour of lithium and beryllium is similar with the second element of the following group, i.e. magnesium and aluminium.
This type of similarity is known as diagonal relationship in periodic properties.
Different chemical behaviour of the first member of s-block and p-block: o The first member of a group of elements in the s-block and p-block shows different chemical behaviour to that of the subsequent members in the same group.
Periodic Trends and Chemical Reactivity
All chemical and physical properties are a manifestation of the electronic configuration of elements.
Variation in a period
Reaction with Oxygen
Variation in a Group
General Properties of Periodic Table
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