Introduction, position in periodic table, transition elements & inner transition elements, lanthanoids & actinoids, General trends in properties, atomic radii, atomic volume, melting points, boiling points, density, standard electrode potentials, oxidation states, Some practice questions.
The bonding in lanthanide complexes differs from that seen in transiti.docxchrisflorence13710
The bonding in lanthanide complexes differs from that seen in transition metal complexes. Discuss how this difference in bonding explains why for a transition metal ion, such as Co3+, the colour of its complexes varies depending on the co-ordinated ligands, whilst all complexes of a particular lanthanide ion, such as Eu3+, exhibit a similar colour (b)
Solution
Lanthanides (inner transition metals) resemble 3d transition metals mainly in forming coloured complexes.
But they differ in the oxidation state which is due to large reduction potential for oxidation state when related to 1 electron reduction in case transition compounds.
There is a lack in 4f chemistry of very high oxidation state is familiar to 3d transition complexes. The 4f metals are not willing to form strong Ln = O double bond complexes and lack of significant third ionization energy IE 3 is important in maintaining +3 oxidation state at the end of the lanthanide series.
The increase in atomic radius is greater than between 3d and 4d metals than between the 4d and 5d metals because of lanthanide contraction.
Sigma bonding interaction in coordination compound is due to attraction of electrons on the ligand for the charge of metal ion.
Electrons in ligands repel electrons in unhybridised d orbital of metal ion. The transition metal ion like Co +3 complexes exhibit many intense colours in host crystals or solutions.
The colour of light absorbed by complexed ion is related to electronic energy changes in structure of complex.
The electron leaping from a lower energy state to a higer energy state. If the crystal field strength is weak and the energy gap is small leading to unpaired electrons and form a paramagnetic complex in case of 4th and 5th electron going to higher energy d z 2 and d x 2 - d y 2 .
The fourth through 6 electrons will pair with d xy , d yz , and d zx . if the field is strong and the energy gap is large, leading to paired electrons and a diamagnetic complex
The colour of transition metal ion, Co +3 complexes differs depends on the coordinated ligands, which is due to change in electronic energy in the structure of complex while colour of particular lanthainde Eu 3+ (europium) exhibit similar pale pink clour this is due to f-->f transition rather than d--->d transition.
.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Introduction, position in periodic table, transition elements & inner transition elements, lanthanoids & actinoids, General trends in properties, atomic radii, atomic volume, melting points, boiling points, density, standard electrode potentials, oxidation states, Some practice questions.
The bonding in lanthanide complexes differs from that seen in transiti.docxchrisflorence13710
The bonding in lanthanide complexes differs from that seen in transition metal complexes. Discuss how this difference in bonding explains why for a transition metal ion, such as Co3+, the colour of its complexes varies depending on the co-ordinated ligands, whilst all complexes of a particular lanthanide ion, such as Eu3+, exhibit a similar colour (b)
Solution
Lanthanides (inner transition metals) resemble 3d transition metals mainly in forming coloured complexes.
But they differ in the oxidation state which is due to large reduction potential for oxidation state when related to 1 electron reduction in case transition compounds.
There is a lack in 4f chemistry of very high oxidation state is familiar to 3d transition complexes. The 4f metals are not willing to form strong Ln = O double bond complexes and lack of significant third ionization energy IE 3 is important in maintaining +3 oxidation state at the end of the lanthanide series.
The increase in atomic radius is greater than between 3d and 4d metals than between the 4d and 5d metals because of lanthanide contraction.
Sigma bonding interaction in coordination compound is due to attraction of electrons on the ligand for the charge of metal ion.
Electrons in ligands repel electrons in unhybridised d orbital of metal ion. The transition metal ion like Co +3 complexes exhibit many intense colours in host crystals or solutions.
The colour of light absorbed by complexed ion is related to electronic energy changes in structure of complex.
The electron leaping from a lower energy state to a higer energy state. If the crystal field strength is weak and the energy gap is small leading to unpaired electrons and form a paramagnetic complex in case of 4th and 5th electron going to higher energy d z 2 and d x 2 - d y 2 .
The fourth through 6 electrons will pair with d xy , d yz , and d zx . if the field is strong and the energy gap is large, leading to paired electrons and a diamagnetic complex
The colour of transition metal ion, Co +3 complexes differs depends on the coordinated ligands, which is due to change in electronic energy in the structure of complex while colour of particular lanthainde Eu 3+ (europium) exhibit similar pale pink clour this is due to f-->f transition rather than d--->d transition.
.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
2. Introduction-
The elements which have partially filled d-orbitals, either in the
atomic state or in the common oxidation state, are known as
transition elements. They are also known as d-block elements.
These elements appear in the middle part of the periodic table
between s and p-block elements. These elements, for the first
time, appear in fourth period. Thus, the elements from Sc(21)
to Cu (29) constitute first transition series. Other transition
series also begin from IIIB group and terminate at IB group.
Second transition series is constituted by the elements from
yttrium (39) to silver 47 and the third from lanthanum (57) and
hafnium (72) to gold (79).
3. Metallic radii
Metallic radii of second transition series elements are as expected. These
elements are larger by ~0.8 to 1.7Å than the first transition series elements.
In a transition series electrons enter the (n - 1)d orbitals due to which on
increasing atomic number by one, there is an increase of only 0.15 in the
effective nuclear charge. Thus, the decrease in metallic radius in a
transition series is small, as expected. Shrinkage in lighter elements in a
transition series is expectedly more because with the decrease in size,later
the electrons come closer and mutual repulsion increases and opposes
shrinkage. Consequently, atomic radii remain almost constant in the
middle but increase at the end of the series due to the attainment of d10
configuration. Gradation of atomic radii in the third transition series is
similar to that in the second series.
4.
5.
6. Atomic weight and density
Sizes of the members of both transition series are equal
but in IV B and the following groups it may be seen that
the atomic weight of a III transition series member is
nearly 1.5 times that of the element of second transition
series placed just above it. This trend is also reflected from
their densities. The ratio of their densities is nearly the
same as that of molecular weights.
7. Melting and boiling points
Transition metal group, the melting and boiling points of the
second element are higher than those of the first element and
the melting and boiling points of the third element are higher
than those of the second element. Melting point of silver is
lower than that of copper and gold. Existence of copper and
gold in higher oxidation state (+2 or +3) in their compounds
indicates participation of d orbitals to a greater extent in these
elements than silver. Thus, it may be concluded that in metallic
state the bonds between the atoms of silver are weaker than in
both copper and gold. This is the reason of the lower melting
point of silver.
8. Ionisation energy
The ionisation energy of second and third transition series
elements is medium order which indicates that these elements
have a tendency to form cations. Ionisation energies of IIIB group
elements are comparatively lower. Hence, they have a greater
tendency to form cations.In a group, generally the ionisation
energy decreases with the increase in atomic number so that the
first and the second transition series elements have nearly equal
values. The ionisation energy of the third series elements is higher
than that of the second which is due to lanthanide contraction. It
may be seen that for the members present at the end of the
series, the ionisation enegy increases rapidly which is due to the
completely filled (d10) configuration.
9. Hardness and mechanical strength
Metal are also melleable, ductile and have good
mechanical strength.
10. Oxidation state
On comparing the oxidation states of the elements of the first transition series with
those of the second and third series, it is observed that the latter have greater tendency
to exhibit higher oxidation states. It may also be observed that +2 is a common state for
the first transition series elements (except Sc), whereas for the heavier elements it is a
very uncommon state-only Pd(II) and Pt(II) form bipositive species. When we going
down a transition metal group, instability of lower state and stability of higher state
increases. Due to this reason, for the middle elements both the higher and lower states
are equally stable, whereas the first and the third elements exhibit mutually opposite
behaviour. For example,
cobalt both Co(II) and Co(III) are known, whereas the heavier elements of the group Rh
and Ir exhibit +3 or higher oxidation states.
chronium +3 state is most important but in this state both molybdenum and tungesten
are strongly reducing. In addition to this, +6 state is common and stable for the latter,
whereas Cr(IV) is strongly oxidising. Ru and Os form compound RuO, and OsO4 in +8
oxidation state but Fe does not.
11.
12.
13. Tendency to form coordination
compounds
Heavy transition elements also have a tendency to form
coordination compounds, In the spatial distribution of d-
orbitals. 3d- orbitals do not have any node and hence are
compact, whereas 4d and 5d-orbitals have one and two
radial nodes respectively and hence have more extension
in space i.e. they are diffused. Due to large size, heavy
transition elements exhibit 6 coordination number,
although, a number of compounds with still higher
coordination numbers are known.
14. Comparison with 3d analogues
Ionic radii - It has already been discussed that in between the 4d and
5d levels is interposed the 4f shell which fills after lanthanum. The
occupation of this level is accompanied by a gradual decrease in
atomic and ionic radii from La to Lu and the total decrease in size
within the lanthanide series, known as lanthanide contraction is
approximately equal to the normal increase in size between one
period and the next. The result is that in the transition groups there is
the normal increase of about 0.2 Å in radius between the first and
the second transition series members (filling the 3d and 4d
subshells) but the expected increase between the second and third
members is just balanced by the lanthanide contraction so that these
two elements are almost identical in size.
15.
16. Oxidation state -
Higher oxidation states for heavier transition elements in general
much more stable than for the elements of the first transition series.
The stability of higher oxidation state is exhibited by their very little
tendency to undergo reduction. The compounds of lighter elements
in higher oxidation states are easily reduced. In fact, the number of
compounds of heavier transition elements in higher oxidation states
is so large that these states appear to be the common oxidation states
for these elements.
17. Magnetic behaviour
Magnetic moment may be determined experimentally and the
number of unpaired electrons may be calculated from the magnetic
moment. In transition metal compounds, the knowledge of the
number of unpaired electrons, that are present in a molecule, is used
to interprete their many features like struture, stereochemistry and
spectra. Number of unpaired electrons in metal ions may be
calculated by the following relation.
18. Where u is magnetic moment which is measured in Bohr magneton
(BM) unit, g is gyromagnetic ratio and the total spin quantum
number of all the electrons is S which is equal to nx1/2=- N /2 where
n is the number of unpaired electrons. For the first transition series
elements, g=2. substituting these values of g and S, we get the
following relationship between μ and the number of unpaired
electrons n.μ = 2 +1μ = √n(n+2)
19. One important characteristic of the heavier transition elements is that they tend to form low spin
compounds (∆> π), whereas the elements of the first transition series form both low spin and high
spin compounds. Low spin compounds are those in which the number of unpaired electrons is
minimum. In contrast to this, in high spin compounds the number of unpaired electrons is
maximum. In transition metal is ions, all the five d-orbitals are of same energy i.e. they are
degenerate. But when they form compounds, they split into different sets of energy for octahedral
geometry. The energy difference between the lower energy and higher energy orbitals is known as
splitting energy and is represented by ∆. The energy required to pair two electrons is known as
pairing energy which is represented by л. The value of ∆ is lower than л (∆<л) for high spin
complexes, whereas for low spin compounds ∆ value is comparatively higher (∆>T). In the
heavier elements, greater tendency of pairing of spins is due to two reasons. First, pairing energy
(л) for the heavier elements is lower than that for the lighter elements. This is because the 4d and
5d orbitals are larger than 3d orbitals. Due to more space the interelectronic repulsion between two
electrons is significantly less. As a result, the pairing energy will be lower in comparison to 3d
orbital
Second the splitting of d orbitals
20.
21. Stereochemistry -
Transition metal complexes can have different shapes depending on
its coordination number. The shapes that are common for transition
metal complexes formed using monodentate ligands (ligands which
only form one bond to the central metal ion or atom) are tetrahedral,
square planar and octahedral, as shown below. 6-co-ordinated
complex ions, in which the central metal is attached to six
ligands, have an octahedral shape . On the other hand, 4-co-
ordinated complex ions, in which the central metal is attached to
four ligands, can either have a tetrahedral or square planar shape.