The document discusses the structure of atoms. It explains that atoms are made up of subatomic particles like electrons, protons, and neutrons. J.J. Thomson discovered the electron, while E. Goldstein discovered the positively charged particle, which was later named the proton. Ernest Rutherford's alpha particle scattering experiment provided evidence that the mass and positive charge of an atom are concentrated in a small, dense nucleus at the center. Niels Bohr later proposed that electrons orbit the nucleus in well-defined energy levels or shells. In 1932, James Chadwick discovered the neutron, which has no charge and a mass similar to a proton. The structure of atoms is defined by the number of protons, which determines the element, and
Atom - the fundamental unit of matter. From its discovery to its structural analysis, it amazes us. In this chapter you will study about beginner level of atomic structure and how scientists have contributed in making the structure of atom present today
Atom - the fundamental unit of matter. From its discovery to its structural analysis, it amazes us. In this chapter you will study about beginner level of atomic structure and how scientists have contributed in making the structure of atom present today
Best PowerPoint presentation on NCERT class 9 Atoms and Molecules as per CBSE syllabus it covers full chapter with all information.
By Raxit Gupta
9C
KENDRIYA VIDYALAYA BALLYGUNGE
This presentation is specially made for the students of grades 11 and 12 of High School. This is the presentation of chapter Atomic Structure with proper diagrams, figures, facts, mnemonics, and some repeated past questions. Here you will get a chance to know about Atomic theory, Daltons Law, particles and so on.
Best PowerPoint presentation on NCERT class 9 Atoms and Molecules as per CBSE syllabus it covers full chapter with all information.
By Raxit Gupta
9C
KENDRIYA VIDYALAYA BALLYGUNGE
This presentation is specially made for the students of grades 11 and 12 of High School. This is the presentation of chapter Atomic Structure with proper diagrams, figures, facts, mnemonics, and some repeated past questions. Here you will get a chance to know about Atomic theory, Daltons Law, particles and so on.
This pdf is written to describe structure of atom for school students of grades 9 to 10. In this the basics of atomic structure has been described. Starting from Dalton's atomic model to Rutherford's scatering of alpha particles, JJ Thomson and Bohr's models with photos.
Students can download and use it for studying atomic structure.
Indeed, the structure of an atom is fundamental to understanding the properties and behaviour of matter. At its core, an atom consists of three primary subatomic particles: protons, neutrons, and electrons. These constituents collectively determine the atom's mass and charge.
To learn more about VAVA Classes, visit: www.vavaclasses.com
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.
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.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
2. The existence of different kinds of matter is due to
different atoms constituting them. Two questions
arise: (i) What makes the atom of one element
different from the atom of another element? and
(ii) Are atoms really indivisible, or are there
smaller constituents inside the atom? One of the
first indications that atoms are not indivisible,
comes from studying static electricity and the
condition under which electricity is conducted by
different substances
• Introduction
3. • Charged Particles in Matter
Many scientists contributed in revealing the presence
of charged particles in an atom. It was known by 1900
that the atom was not a simple, indivisible particle but
contained at least one sub-atomic particle – the
electron identified by J.J. Thomson.
E. Goldstein in 1886 discovered the presence of new
radiations in a gas discharge and called them canal
rays. These rays were positively charged radiations
which ultimately led to the discovery of another sub-
atomic particle. This sub-atomic particle had a charge,
equal in magnitude but opposite in sign to that of the
electron.
4. Its mass was approximately 2000 times as that of the electron. It
was given the name of proton. In general, an electron is represented
as ‘e–’ and a proton as ‘p+’. The mass of a proton is taken as one unit
and its charge as plus one. The mass of an electron is considered to
be negligible and its charge is minus one
• The Structure of an Atom
J.J. Thomson was the first one to propose a
model for the structure of an atom.
THOMSON’S MODEL OF AN ATOM Thomson
proposed that: (i) An atom consists of a
positively charged sphere and the electrons are
embedded in it.
5. (ii) The negative and positive charges are equal in magnitude. So, the
atom as a whole is electrically neutral. Although Thomson’s model
explained that atoms are electrically neutral, the results of
experiments carried out by other scientists could not be explained by
this model.
6. • RUTHERFORD’S MODEL OF AN ATOM
Ernest Rutherford was interested in knowing how the
electrons are arranged within
an atom. Rutherford designed an experiment for this.
In this experiment, fast
moving alpha ( )-particles were made to fall on a thinα
gold foil.
• He selected a gold foil because he wanted as thin a
layer as possible. This gold foil
was about 1000 atoms thick.
• -particles are doubly-charged helium ions. Sinceα
they have a mass of 4 u, the
fast-moving -particles have a considerable amountα
of energy.
For Video Click Here
7. • It was expected that -particles would be deflected by the sub-α
atomic particles in
The gold atoms. Since the -particles were much heavier than theα
protons, he did not
Expect to see large deflections
8. The following observations were made:
(i) Most of the fast moving -particles passed straight through the gold foil.α
(ii) Some of the -particles were deflected by the foil by small angles.α
(iii) Surprisingly one out of every 12000 particles appeared to rebound.
Rutherford concluded from the -particle scattering experiment that–α
(i) Most of the space inside the atom is empty because most of the -α
particles passed through the gold foil without getting deflected.
(ii) Very few particles were deflected from their path,
indicating that the positive
charge of the atom occupies very little space.
(iii) A very small fraction of -particles were deflectedα
by 1800, indicating that all the
positive charge and mass of the gold atom were
concentrated in a very small volume
9. On the basis of his experiment, Rutherford put forward the nuclear model
of an
atom, which had the following features:
(i) There is a positively charged centre in an atom called the nucleus.
Nearly all the
mass of an atom resides in the nucleus.
(ii) The electrons revolve around the nucleus in well-defined orbits.
(iii) The size of the nucleus is very small as compared to the size of the
atom.
10. Drawbacks of Rutherford’s model
of the atomThe orbital revolution of the electron is not expected to be stable. Any
particle in a
circular orbit would undergo acceleration. During acceleration, charged
particles
would radiate energy. Thus, the revolving electron would lose energy
and finally fall into the nucleus. If this were so, the atom should
be highly unstable and hence
matter would not exist in the form that we know.
We know that atoms are quite
stable.
11. Q-1 : Electron was discovered by___________.
A. Chadwick
C. Goldstein D. Bohr
B. Thomson
19. Q-3 : Rutherford’s ‘alpha ( ) particles scatteringα
experiment’ resulted in to discovery of
A. Electron
C. Nucleus in the atom D. Atomic mass
B. Proton
31. • BOHR’S MODEL OF ATOM
In order to overcome the objections raised against Rutherford’s model
of the atom,
Neils Bohr put forward the following postulates about the model of an
atom:
(i) Only certain special orbits known as discrete orbits of electrons,
are allowed inside
the atom. (ii) While revolving in discrete orbits the electrons
do not radiate energy. These orbits or shells are
called energy levels.
Click Here For Video
32. These orbits or shells are represented by the
letters K,L,M,N,… or the numbers,
n=1,2,3,4,….
33. • NEUTRONS
In 1932, J. Chadwick discovered another subatomic particle which had no
charge and
a mass nearly equal to that of a proton. It was eventually named as
neutron.
Neutrons are present in the nucleus of all atoms, except hydrogen. In
general, a neutron is represented as ‘n’. The mass of an atom is therefore
given by
the sum of the masses of protons and neutrons
present in the nucleus.
34. How are Electrons Distributed in
Different Orbits (Shells)?
The distribution of electrons into different orbits of an atom was
suggested by Bohr and Bury.
The following rules are followed for writing the number of electrons in
different energy levels or shells:
(i) The maximum number of electrons present in a
shell is given by the formula 2n2,where ‘n’ is the
orbit number or energy level index, 1,2,3,…. Hence
the maximum number of electrons in different
shells are as follows:
35. first orbit or K-shell will be = 2 × 1^2 = 2,
second orbit or L-shell will be = 2 × 2^2 = 8,
third orbit or M-shell will be = 2 ×3^2 = 18,
fourth orbit or N-shell will be = 2 × 4^2= 32, and so on.
(ii) The maximum number of electrons that can be accommodated in the
outermost orbit is 8.
(iii) Electrons are not accommodated in a given shell, unless the inner
shells are
filled. That is, the shells are filled in a step-wise manner.
36. Q-6 : Chadwick got the Nobel Prize for the
discovery of __________.
A. Protons
C. Electrons D. Mesons
B. Neutrons
56. • Valency
The electrons present in the outermost shell of an atom are known as
the valence electrons. Valency or valency number, is a measure of the
number of chemical bonds formed by the atoms of a given element.
According to Bohr-Bury, outermost shell of an atom can have two
electrons in its outermost shell and all other elements have atoms with
eight electrons in the outermost shell. The combining capacity of the
atoms of other elements, that is, their tendency to react and form
molecules with atoms of the same or different
elements was thus explained as an attempt to
attain a fully-filled outermost shell. An outermost-
shell, which had eight electrons was said to
possess an octet. Atoms would thus react, so as to
achieve an octet in the outermost shell.
57. This was done by sharing, gaining or losing electrons.
The number of electrons gained, lost or shared so as to make the octet of
electrons in the outermost shell, gives us directly the combining capacity
of the element.
For example, hydrogen/lithium/sodium atoms contain one electron each in
their outermost shell, therefore each one of them can lose one electron.
So, they are said to have valency of one. If the number of electrons in the
outermost shell of an atom is close to its full capacity, then valency is
determined in a different way.
Valency can be calculated in a similar manner for
oxygen. Therefore, an atom of each element has a
definite combining capacity, called its valency
Click Here For Video
58. The number of protons in the nucleus of an atom determines an
element's atomic number. Each element has a unique number that
identifies how many protons are in one atom of that element. For
example, all hydrogen atoms,and only hydrogen atoms, contain one
proton and have an atomic number of 1.
• ATOMIC NUMBER
All carbon atoms, and only carbon atoms, contain six
protons and have an atomic number of 6. Oxygen
atoms contain 8 protons and have an atomic number
of 8. The atomic number of an element never changes,
meaning that the number of protons in the nucleus of
every atom in an element is always the same.
59. • MASS NUMBER
Mass of an atom is practically due to protons and neutrons alone.
These are present in the nucleus of an atom. Hence protons and neutrons
are also called nucleons. Therefore, the mass of an atom resides in its
nucleus. For example, mass of carbon is 12 u because it has 6 protons
and 6 neutrons, 6 u + 6 u = 12 u. Similarly, the mass of aluminum is 27 u
(13 protons+14 neutrons). The mass number is defined as the sum of
the total number of protons and neutrons present in
the nucleus of an atom.
All atoms have a mass number which is derived as
Follows
Number of Neutrons + Number of Protons = Mass Number
60. Q-11 : Mass number is equal to the_________.
A. No. of protons+ No. Of electrons
B. No. of protons+ No. Of neutrons
C. No. of neutrons + No. Of electrons
D. No. Of electrons
76. Q-15 : The ion of an element has 3 positive
charges. Mass number of the atom is 27 and the
number of neutrons is 14. What is the number of
electrons in the ion?
C. 14
A. 13
D. 16
B. 10
