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1. Nuclear model of the atom). According to this the entire positive charge and most of the mass of the atom is concentrated in a small volume called the nucleus with electrons revolving around the nucleus just as planets revolve around the sun. Rutherford’s nuclear model was a major step towards how we see the atom today.
2. Fill in the Blank of the Following Statement: Almost All the Mass of an Atom is Concentrated in a Small Region of Space Called the. CBSE CBSE Class 9. Textbook Solutions 8950. All the mass of an atom is concentrated in a small region of space called the. Advertisement Remove all ads.

1. Almost The Entire Mass Of An Atom Is Concentrated In The __
2. Almost The Entire Mass Of An Atom Is Concentrated In The Nucleus
3. Almost The Entire Mass Of An Atom Is Concentrated In The

Faculty and Staff Directory

These are deflected by the nucleus. It means that almost the entire mass of the atom lies at its center, i.e., entire mass of an atom is concentrated inside its nucleus.

Almost The Entire Mass Of An Atom Is Concentrated In The __

Yordanka Ilieva

Research Focus

Although ninety-eight percent of the mass of ordinary matter is due to the strong subatomic force,
the present theory of that force (Quantum Chromodynamics) is still not fully understood. Almost
the entire mass of an atom is concentrated in its tiny nucleus, which is made of nucleons that are
either positively charged (protons) or electrically neutral (neutrons). These subatomic particles,
however, are not elementary but are themselves composite objects made of quarks held together
by glue particles (gluons). The structure of nucleons is a manifestation of the strong force, which
is indeed the strongest force known. The core of Prof. Ilieva’s research is the study of the strong
force by probing the substructure of matter. Her research activities help to address overarching
questions about the origin of most of the visible mass in the universe, the nature of neutron stars,
and the gluonic structure of nucleons and light nuclei. Answering these and related questions is a
complex task requiring dedicated experimental observations and careful testing of theoretical
predictions against measured observations. Professor Ilieva’s research also promotes teaching,
training, and learning. The preparation of junior scientists plays a central role in her program.
The nuclear physics research program of Professor Ilieva is primarily based at the Thomas Jefferson
National Accelerator Facility (JLab) in Newport News, where she uses high-energy electron and
photon beams along with sophisticated particle detectors as powerful microscopes to study the
structure and interaction of baryons. Her program provides crucial high-precision, polarized and
unpolarized photo-production observables that will help pin down present problems in strong
QCD. For example, complete and mostly complete meson-photoproduction measurements will
settle in an almost model-independent way lingering problems in baryon spectroscopy and in
particular verify the SU(6)xO(3) three quark baryon structure. The structure of baryons can be
also probed through their interactions in scattering processes. The study of strong interactions
involving the strange and the charm quarks is essential to understand the properties of neutron
stars and the gluonic structure of bound nucleons and light nuclei, respectively. Professor Ilieva
carries a comprehensive study of hyperon photo-production off deuterons. The extensive set of
single- and double-polarization observables will provide long-needed experimental information
on the hyperon-nucleon interaction. At the recently upgraded 12-GeV JLab, she carries out a
program on J/psi photoproduction off deuteron. This research will provide the very first crosssection
estimates at energies close to threshold. Another aspect of her research is to support the
detector development for a future Electron-Ion Collider in the U.S. She carries out an assessment
of the performance of commercially available small photosensors in high magnetic fields in her
test facility at Jefferson Lab.

Who did the Gold Foil Experiment?

The gold foil experiment was a pathbreaking work conducted by scientists Hans Geiger and Ernest Marsden under the supervision of Nobel laureate physicist Ernest Rutherford that led to the discovery of the proper structure of an atom. Known as the Geiger-Marsden experiment, it was performed at the Physical Laboratories of the University of Manchester between 1908 and 1913.

Gold Foil Experiment

History

The prevalent atomic theory at the time of the research was the plum pudding model that was developed by Lord Kelvin and further improved by J.J. Thomson. According to the theory, an atom was a positively charged sphere with the electrons embedded in it like plums in a Christmas pudding.

With neutrons and protons yet to be discovered, the theory was derived following the classical Newtonian Physics. However, in the absence of experimental proof, this approach lacked proper acceptance by the scientific community.

What is the Gold Foil Experiment?

Description

Almost The Entire Mass Of An Atom Is Concentrated In The Nucleus

The method used by scientists included the following experimental steps and procedure. They bombarded a thin gold foil of thickness approximately 8.6 x 10^-6 cm with a beam of alpha particles in a vacuum. Alpha particles are positively charged particles with a mass of about four times that of a hydrogen atom and are found in radioactive natural substances. They used gold since it is highly malleable, producing sheets that can be only a few atoms thick, thereby ensuring smooth passage of the alpha particles. A circular screen coated with zinc sulfide surrounded the foil. Since the positively charged alpha particles possess mass and move very fast, it was hypothesized that they would penetrate the thin gold foil and land themselves on the screen, producing fluorescence in the part they struck.

Like the plum pudding model, since the positive charge of atoms was evenly distributed and too small as compared to that of the alpha particles, the deflection of the particulate matter was predicted to be less than a small fraction of a degree.

Observation

Though most of the alpha particles behaved as expected, there was a noticeable fraction of particles that got scattered by angles greater than 90 degrees. There were about 1 in every 2000 particles that got scattered by a full 180 degree, i.e., they retraced their path after hitting the gold foil.

Simulation

Simulation of Rutherford’s Gold Foil Experiment
Courtesy: University of Colorado Boulder

Conclusion

The unexpected outcome could have only one explanation – a highly concentrated positive charge at the center of an atom that caused an electrostatic repulsion of the particles strong enough to bounce them back to their source. The particles that got deflected by huge angles passed close to the said concentrated mass. Most of the particles moved undeviated as there was no obstruction to their path, proving that the majority of an atom is empty.

Almost The Entire Mass Of An Atom Is Concentrated In The

In addition to the above, Rutherford concluded that since the central core could deflect the dense alpha particles, it shows that almost the entire mass of the atom is concentrated there. Rutherford named it the “nucleus” after experimenting with various gases. He also used materials other than gold for the foil, though the gold foil version gained the most popularity.

He further went on to reject the plum pudding model and developed a new atomic structure called the planetary model. In this model, a vastly empty atom holds a tiny nucleus at the center surrounded by a cloud of electrons. As a result of his gold foil experiment, Rutherford’s atomic theory holds good even today.

Rutherford’s Atomic Model

Rutherford’s Gold Foil Experiment Animation

Summary

• Rutherford demonstrated his experiment on bombarding thin gold foil with alpha particles contributed immensely to the atomic theory by proposing his nuclear atomic model.
• The nuclear model of the atom consists of a small and dense positively charged interior surrounded by a cloud of electrons.
• The significance and purpose of the gold foil experiment are still prevalent today. The discovery of the nucleus paved the way for further research, unraveling a list of unknown fundamental particles.

Article was last reviewed on Friday, August 14, 2020