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Questions and Answers
What is the range of atomic numbers for the actinide series elements in the periodic table?
Which of the following actinides is not naturally occurring on earth?
What is the general electronic configuration of actinides?
What is the term 'actinide series' derived from?
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What is the purpose of americium in modern smoke detectors?
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Why are actinides used in nuclear reactors and nuclear weapons?
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What is the primary reason for the actinide contraction?
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Which of the following statements is true about the oxidation states of actinides?
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Why are actinides more reactive than lanthanides?
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What is the correct trend in the formation of complexes by actinides?
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What is the reason for the magnetic properties of actinides?
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What is the primary reason for the formation of coloured ions by actinides?
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What is the main difference between naturally occurring and transuranic actinides?
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What is the primary characteristic of all actinides?
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What is the purpose of the symbol An in the context of actinides?
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Where are the actinides and lanthanides placed in the modern periodic table?
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What is the most abundant naturally occurring actinide on earth?
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What is the energy release pattern of actinides?
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What is the reason for the larger contraction in the actinide series compared to the lanthanide series?
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What is the most stable oxidation state of actinides?
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Why do actinides form coloured ions?
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What is the trend in the density of actinides?
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Why do actinides have lower ionization enthalpies than lanthanides?
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What is the order of degree of complexion in actinides?
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Study Notes
Actinides
- Actinides are elements with atomic numbers from 90 to 103, following the element Actinium.
- They include naturally occurring elements of thorium, protactinium, and uranium, and eleven transuranic, i.e., artificially produced by nuclear reactions.
- All actinides are radioactive.
Electronic Configuration
- The general electronic configuration of actinides is [Rn] 5f1-14 6d0-1 7s2.
- The energy of 5f and 6d electrons are close to each other, and so electrons enter into the 5f orbital.
Actinide Contraction
- The atomic size/ionic radii of tri positive actinides ions decrease steadily from Th to Lw due to increasing nuclear charge and electrons entering the inner (n-2) f orbital.
- This gradual decrease in size with an increasing atomic number is called actinide contraction, similar to lanthanide contraction.
Formation of Coloured Ions
- Actinides like lanthanide ions have electrons in the f-orbital and also empty orbitals like the d-block elements.
- When a frequency of light is absorbed, the f-f electron transition produces a visible colour.
Ionization of Actinides
- The actinides have lower ionization enthalpies than lanthanides because 5f electrons are more effectively shielded from nuclear charge than 4f.
Oxidation State of Actinides
- Actinides show variable oxidation states because of the smaller energy gap between 5f, 6 d, and 7s orbitals.
- Though 3+ is the most stable oxidation state, other oxidation states are possible because of the good shielding of f-electrons.
Formation of Complexes
- Actinides are better complexing agents than lanthanides due to their smaller size but higher nuclear charge.
- They can form Pπ – complexes as well.
- The degree of complexion decreases in the order M4+ > MO22+ > M3+ > MO22+.
Chemical Reactivity of Actinides
- Because of the lower ionization energy, actinides are more electropositive than lanthanides and most reactive.
- They react with hot water and react with oxidizing agents and form a passive coating, forming halides and hydrides.
- Actinides are strong reducing agents.
Physical Properties of Actinides
- Density of Actinides: All actinides except thorium and americium have very high densities.
- Melting and Boiling Points of Actinides: Actinides have fairly high melting points, like lanthanides, but there is no definite trend in the melting and boiling point of lanthanides.
- Magnetic Properties of Actinides: All actinides are paramagnetic in nature, which depends on the presence of unpaired electrons.
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Description
This quiz covers the Actinide series of elements, including their properties, characteristics, and types. Learn about the naturally occurring and transuranic elements in the Actinide series, and test your knowledge of these radioactive elements.
