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D-Block and F-Block Elements: Physical Properties of Transition Elements
Physical Properties of Transition Elements
Characteristics Properties
Variable Oxidation States
- The number of electrons used for bonding by an electropositive element is equal to its positive oxidation state.
- A characteristic property of d-block elements is their ability to exhibit a variety of oxidation states in their compounds.
- This is due to that for bonding elements can use inner electrons as well because of very small difference in their energies.
- Depending upon the number of d electrons involved in bonding, they shows different oxidation states.
- The lowest oxidation state is usually equal to the number of s-electrons present (except ) .
- The highest oxidation states are observed in compounds with fluorine and oxygen.
The different oxidation states of elements of the first transition series are given below:
- Except for scandium, the most common oxidation state of elements is , which arises from the loss of two electrons.
- Compounds having oxidation states and of these elements have ionic bonds whereas bonds are essentially covalent in higher oxidation states.
- For example , , bonds formed between manganese and oxygen are covalent.
- The acid base character of the oxides can be inferred from the oxidation states.
- Increase in oxidation state leads to decrease in basic character of the oxide and vice-versa.
Magnetic Properties
- Substances possess two types of magnetic Behaviour, either diamagnetism or paramagnetic.
- Diamagnetic substances are either repelled or remain unaffected by an applied magnetic field.
- Paramagnetic substances are attracted towards the applied field.
- There is a strong co-relation between the magnetic Behaviour, electronic configuration and oxidation state.
- Para magnetism arise due to presence of unpaired electrons.
- Transition metals ions generally contains unpaired electrons a large number of transition metal ions exhibit paramagnetic Behaviour.
- Magnetic moment of paramagnetic material can be calculated by expression: is the number of unpaired electron.
Magnetic Moments of Some Ions of the Transition Elements
Compounds containing , , , , and ions are diamagnetic because these ions do not contain unpaired electrons.
Colour of Ions and Compounds
Most of the compounds of d-block elements are colored or they give colored solution when dissolved in water (Table) .
Colours of Hydrated Ions of Some Transition Elements
- In transition metal compounds colour is generally associated with incomplete subshell of the transition metal.
- When white light interacts with a substance, a part of it is absorbed by the substance.
- For example, if red portion of white light is absorbed by a substance, it would appear blue.