Actinoids Flashcards
Actinoids are
Ac , Th to Lr 14 elements
Earlier members have ____ half life
Later members have half life ranging from ____ to 3 min thus could be prepared in nanograms only
Longer
One day
Q: What is the general electronic configuration of actinoids?
A: The general electronic configuration of actinoids is 7 s² with variable occupancy of the 5 f and 6d subshells.
How many electrons are formally added to the subshell in actinoids?
A: Fourteen electrons are formally added to the subshell.
Q: At which element do the orbitals become complete in actinoids?
A: The orbitals become complete at element 103 (Lawrencium).
Q: From which element onwards do the orbitals begin filling in actinoids?
A: The orbitals begin filling from Protactinium (Pa, ) onwards.
Q: From which element onwards do the orbitals begin filling in actinoids?
A: The orbitals begin filling from Protactinium (Pa, ) onwards.
Q: What causes the irregularities in the electronic configurations of actinoids?
A: The irregularities are related to the stabilities of f⁰ f⁷ , and f¹⁴ occupancies of the 5f orbitals.
Q: What are the electronic configurations of Americium (Am) and Curium (Cm)?
A:
Americium (Am): Rn 5f⁷ 7s²
Curium (Cm):Rn 5f⁷ 6d¹ 7s²
Q: How do 5f orbitals differ from 4f orbitals but resembles in angular wave function ?
A: 5f orbitals are less buried than 4 f orbitals, allowing electrons to participate in bonding to a greater extent.
Q: How do 5f orbitals differ from 4f orbitals but resembles in angular wave function ?
A: 5f orbitals are less buried than 4 f orbitals, allowing electrons to participate in bonding to a greater extent.
what is actinoid contraction
gradual decrease in size of atoms or M3+ ions across the series
what causes actinoid contractions
poor shielding effect of 5f orbitals
How does the actinoid contraction compared to lanthanoid contractions
actinoid contraction is greater
what is the term used for gradual decrease in size of actinoids
actinoid contractions
Q: Why do actinoids exhibit a greater range of oxidation states?
A: Because the 5f, 6d, and 7s levels are of comparable energies.
Q: What is the general oxidation state of actinoids?
A: +3 oxidation state.
Q: How does the maximum oxidation state change in the first half of the actinoid series?
A: It increases from +4 in Th to +5, +6, and +7 in Pa, U, and Np, respectively, but decreases in the succeeding elements.
How do actinoids resemble lanthanoids in terms of oxidation states?
A: Both have more compounds in the +3 state than in the +4 state.
What happens to +3 and +4 ions of actinoids?
A: They tend to hydrolyze.
Why is it unsatisfactory to describe the chemistry of actinoids solely in terms of oxidation states?
A: Because the distribution of oxidation states is uneven and varies significantly between the early and later actinoid
: Why do +3 and +4 ions of actinoids tend to hydrolyze?
A: Due to their high charge-to-size ratio, which increases their reactivity with water.
Q: Why is it unsatisfactory to review actinoid chemistry in terms of oxidation states?
A
: The distribution of oxidation states is highly uneven: higher oxidation states are common in the early actinoids (e.g., Pa, U, and Np), while later actinoids predominantly show lower oxidation states (e.g., +3), leading to inconsistent behavior across the series.
Q: What is the general appearance of actinoid metals?
A: Actinoid metals are all silvery in appearance.
Why do actinoid metals display a variety of structures?
A: Due to irregularities in their metallic radii.
How do the irregularities in metallic radii compare between actinoids and lanthanoids?
A: The irregularities in metallic radii are far greater in actinoids than in lanthanoids.
Q: How reactive are actinoid metals?
A: Actinoids are highly reactive, especially when finely divided.
What happens when boiling water reacts with actinoid metals?
A: It produces a mixture of oxide and hydride.with non metals
Q: At what temperature do actinoid metals combine with most non-metals?
A: At moderate temperatures.
: How do hydrochloric acid and nitric acid affect actinoid metals?
A: Hydrochloric acid attacks all actinoids, but nitric acid has little effect due to the formation of protective oxide layers.
How do alkalis affect actinoid metals?
A: Alkalis have no action on actinoid metals.
Q:Q: How do the magnetic properties of actinoids compare to lanthanoids?
A: The magnetic properties of actinoids are more complex than those of lanthanoids.
Q: How does the variation in magnetic susceptibility of actinoids relate to the number of unpaired 5f electrons?
A: The variation in magnetic susceptibility roughly parallels that of lanthanoids.
Q: How do the magnetic susceptibility values of lanthanoids compare to actinoids?
A: Lanthanoids have higher magnetic susceptibility values than actinoids.
What is the relationship between the ionization enthalpies of early actinoids and early lanthanoids?
A: The ionization enthalpies of early actinoids are lower than those of early lanthanoids
Why do early actinoids have lower ionization enthalpies than early lanthanoids?
A: Because the 5f orbitals in actinoids are beginning to be occupied and penetrate less into the inner core of electrons, causing them to be more effectively shielded from the nuclear charge compared to the 4f electrons in lanthanoids.
: How do the 5f electrons in actinoids differ from the 4f electrons in lanthanoids in terms of shielding?
: The 5f electrons in actinoids are more effectively shielded from the nuclear charge than the 4f electrons in lanthanoids
Why are outer electrons in actinoids more available for bonding?
: The outer electrons in actinoids are less firmly held due to the shielding effect, making them more available for bonding.
Name a member of the lanthanoid series which is well known
to exhibit +4 oxidation state.
Ce (Z=58)
actinoid contraction is greater than lanthanoid contraction
due to poor shielding effect of 5f electrons
What are the most important construction materials?
A: Iron and steels are the most important construction materials.
What is the production process of iron and steel based on?
A: The production of iron and steel is based on the reduction of iron oxides, removal of impurities, and the addition of carbon and alloying metals such as Cr (chromium), Mn (manganese), and Ni (nickel).
What is TiO used for?
A: TiO (Titanium monoxide) is used in the pigment industry.
What is MnO2 used for?
A: MnO2 (Manganese dioxide) is used in dry battery cells.
What metals are required by the battery industry?
A: The battery industry requires Zn (zinc) and Ni/Cd (nickel-cadmium).
What are the elements of Group 11 traditionally known as?
A: The elements of Group 11 are traditionally called the coinage metals.
Which elements in Group 11 are still associated with coins?
A: Ag (silver) and Au (gold) are still associated with coins, though they are now mainly used for collection items,
What are the UK “copper” coins made of?
A: The UK “copper” coins are made of copper-coated steel.
What are the UK “silver” coins made of?
A: The UK “silver” coins are made of a Cu/Ni alloy (copper-nickel alloy).
Why are metals and/or their compounds from Group 11 important in the chemical industry?
A
: Many of these metals and/or their compounds are essential catalysts in the chemical industry.
What does V2O5 catalyse in the chemical industry?
A: V2O5 (Vanadium pentoxide) catalyses the oxidation of SO2 (sulfur dioxide) in the manufacture of sulfuric acid.
What does TiCl4 with Al(CH3)3 form the basis of?
A: TiCl4 with Al(CH3)3 forms the basis of the Ziegler catalysts used to manufacture polyethylene (polythene).
What catalysts are used in the Haber process?
A: Iron catalysts are used in the Haber process for the production of ammonia from N2/H2 mixtures.
What is polyethylene (polythene) manufactured using?
A: Polyethylene (polythene) is manufactured using the Ziegler catalysts, which are based on TiCl4 with Al(CH3)3.
What is the role of nickel catalysts in the chemical industry?
A: Nickel catalysts enable the hydrogenation of fats to proceed.
What process uses PdCl2 to catalyse the oxidation of ethyne to ethanal?
A: The Wacker process uses PdCl2 (palladium chloride) to catalyse the oxidation of ethyne (acetylene) to ethanal (acetaldehyde).
What are nickel complexes used for in the chemical industry?
.
A: Nickel complexes are useful in the polymerization of alkynes and other organic compounds such as benzene
What is AgBr used for in the photographic industry?
A: AgBr (silver bromide) is used in the photographic industry due to its special light-sensitive properties.
What reaction is catalysed by PdCl2 in the Wacker process?
A: In the Wacker process, PdCl2 catalyses the oxidation of ethyne (acetylene) to ethanal (acetaldehyde).
