Chemical bonding can occur through either ionic bonds or covalent bonds. Ionic bonds result from the electrostatic attraction between oppositely charged ions, while covalent bonds form through the sharing of electrons between atoms. The strength of these bonds can vary considerably, from strong primary bonds to weaker secondary bonds.
The attractive force which holds various constituents (atom, ions, etc.) together and stabilizes them by the overall loss of energy is known as chemical bonding. Therefore, it can be understood that chemical compounds are reliant on the strength of the chemical bonds between its constituents; The stronger the bonding between the constituents, the more stable the resulting compound would be.
The chemical Bond: Electronic concept of valency. Different types of chemical bond e.g. ionic, covalent, coordinate covalent metallic, dipole, hydrogen bond etc. Theories of covalent bonding and hybridization.
The attractive force which holds various constituents (atom, ions, etc.) together and stabilizes them by the overall loss of energy is known as chemical bonding. Therefore, it can be understood that chemical compounds are reliant on the strength of the chemical bonds between its constituents; The stronger the bonding between the constituents, the more stable the resulting compound would be.
The chemical Bond: Electronic concept of valency. Different types of chemical bond e.g. ionic, covalent, coordinate covalent metallic, dipole, hydrogen bond etc. Theories of covalent bonding and hybridization.
The attractive force which holds various constituents (atom, ions, etc.) together and stabilizes them by the overall loss of energy is known as chemical bonding. Therefore, it can be understood that chemical compounds are reliant on the strength of the chemical bonds between its constituents; The stronger the bonding between the constituents, the more stable the resulting compound would be.
chemical bonding and molecular structure class 11sarunkumar31
hybridisation, bonding and antiboding, dipole moment, VSPER theory, Molecular orbital diagram, Phosphorous pentachloride, ionic bond, bond order, bond enthalpy, bond dissociation, sp and sp2hybridisation, hydrogen bonding,electron pair,lone pair repulsion, resonance structure of ozone, how to find electron pair and lone pair, sp3 hybridization of methane.
Chemical bonding 1 is the first of two presentations on Chemical Bonding by Aditya Abeysinghe.This presentation mainly focuses on the basic/principle bonds formed between two or more elements.
A chemical bond is a lasting attraction between atoms that enables the formation of chemical compounds or substance . The bond may result from the electrostatic force of attraction between atoms with opposite charges, or through the sharing of electrons as in the covalent bonds........
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Richard's entangled aventures in wonderlandRichard 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 .
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.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
2. A chemical bond is a lasting attraction
between atoms, ions or molecules that enables the
formation of chemical compounds. The bond may
result from the electrostatic force of attraction
between oppositely charged ions as in ionic bonds
or through the sharing of electrons as in covalent
bonds. The strength of chemical bonds varies
considerably; there are "strong bonds" or "primary
bonds" such as covalent, ionic and metallic bonds,
and "weak bonds" or "secondary bonds" such
as dipole–dipole interactions, the London dispersion
force and hydrogen bonding.
INTRODUCTION
3.
4. a valence electron is an outer
shell electron that is associated with
an atom, and that can participate in the
formation of a chemical bond if the outer
shell is not closed; in a single covalent
bond, both atoms in the bond contribute one
valence electron in order to form a shared
pair. The presence of valence electrons can
determine
the element's chemical properties, such as
its valence—whether it may bond with other
elements and, if so, how readily and with
how many. For a main group element, a
valence electron can exist only in the
outermost electron shell; in a transition
metal, a valence electron can also be in an
inner shell.
5.
6. LEWIS STRUCTURE
Lewis structures, also known as Lewis dot
diagrams, Lewis dot formulas, Lewis dot
structures, electron dot structures, or Lewis
electron dot structures (LEDS), are diagrams that
show the bonding between atoms of a molecule and
the lone pairs of electrons that may exist in the
molecule.[1][2][3] A Lewis structure can be drawn for
any covalentlybonded molecule, as well as coordination
compounds. The Lewis structure was named
after Gilbert N. Lewis, who introduced it in his 1916
article The Atom and the Molecule.[4]Lewis structures
extend the concept of the electron dot diagram by
adding lines between atoms to represent shared
pairs in a chemical bond.
7.
8. OCTET RULE
The octet rule is a chemical rule of
thumb that reflects observation
that atoms of main-group elements tend
to combine in such a way that each
atom has eight electrons in its valence
shell, giving it the same electron
configuration as a noble gas. The rule is
especially applicable
to carbon, nitrogen, oxygen, and
the halogens, but also to metals such
as sodium or magnesium.
9. The valence electrons can be counted using
a Lewis electron dot diagram as shown at the
right for carbon dioxide. The electrons shared by
the two atoms in a covalent bond are counted
twice, once for each atom. In carbon dioxide
each oxygen shares four electrons with the
central carbon, two (shown in red) from the
oxygen itself and two (shown in black) from the
carbon. All four of these electrons are counted in
both the carbon octet and the oxygen octet.
10. MODES OF CHEMICAL COMBINATION
1)BY THE TRANSFER OF ELECTRONS
2)BY SHARING ELECTRONS
3)COORDINATE BONDING
11. Ionic Bonds
An ionic bond is a type of chemical bond formed
through an electrostatic attraction between two
oppositely charged ions. Ionic bonds are formed
between a cation, which is usually a metal, and an
anion, which is usually a nonmetal. Pure ionic bonding
cannot exist: all ionic compounds have some degree of
covalent bonding. Thus, an ionic bond is considered a
bond where the ionic character is greater than the
covalent character. The larger the difference in
electronegativity between the two atoms involved in the
bond, the more ionic (polar) the bond is.
12.
13.
14. A covalent bond, also called a molecular
bond, is a chemical bond that involves the
sharing of electron pairsbetween atoms.
These electron pairs are known as shared
pairs or bonding pairs, and the stable
balance of attractive and repulsive forces
between atoms, when they share electrons,
is known as covalent
bonding.[1][better source needed] For
many molecules, the sharing of electrons
allows each atom to attain the equivalent of
a full outer shell, corresponding to a stable
electronic configuration.
Covalent bond